This commit replaces a nested ?: sequence with clamp(). This does not
reduce the number of lines of code, but it does simplify the line that
it modifies.
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
This new torture_sched_set_normal() function clamps the nice value at
the MIN_NICE..MAX_NICE limits, splatting it these limits are exceeded.
It then invokes sched_set_normal() to set the new value. This prevents
more difficult-to-debug failures within the scheduler.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Currently, rcutorture bypasses lazy RCU by using call_rcu_hurry().
This works, avoiding the dreaded rtort_pipe_count WARN(), but fails to
fully test lazy RCU. The rtort_pipe_count WARN() splats because lazy RCU
could delay the start of an RCU grace period for a full stutter period,
which defaults to only three seconds.
This commit therefore reverts the call_rcu_hurry() instances
back to call_rcu(), but, in kernels built with CONFIG_RCU_LAZY=y,
queues a workqueue handler just before the call to stutter_wait() in
rcu_torture_writer(). This workqueue handler invokes rcu_barrier(),
which motivates any lingering lazy callbacks, thus avoiding the splat.
Reported-by: Saravana Kannan <saravanak@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
struct bpf_arena is opaque to callers outside arena.c. Add two helpers
for struct_ops subsystems that need to reach into an arena:
bpf_arena_map_kern_vm_start(struct bpf_map *map)
returns @map's kern_vm_start. A sched_ext follow-up needs this
to translate kern_va <-> uaddr.
bpf_prog_arena(struct bpf_prog *prog)
returns the bpf_map of the arena referenced by @prog (NULL if
@prog references no arena). The verifier enforces at most one
arena per program. Used by struct_ops callers that auto-discover
an arena from a member prog and need to take a map reference.
Suggested-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Emil Tsalapatis <emil@etsalapatis.com>
Link: https://lore.kernel.org/r/20260522172219.1423324-6-tj@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Add a helper that walks the member progs of the struct_ops map
containing a given @kdata vmtable. struct_ops ->reg() callbacks (and
similar) sometimes need to inspect the loaded BPF programs, e.g. to
discover maps they reference via prog->aux->used_maps.
The implementation mirrors bpf_struct_ops_id(): container_of @kdata
to recover the bpf_struct_ops_map, then iterate st_map->links[i]->prog
for i in [0, funcs_cnt). Same access pattern, no new locking - by the
time ->reg() fires st_map is fully populated and stable.
A sched_ext follow-up walks the member progs of a cid-form scheduler's
struct_ops map, reads prog->aux->arena directly, and requires all member
progs to reference exactly one arena, without requiring the BPF program
to call a registration kfunc.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Emil Tsalapatis <emil@etsalapatis.com>
Link: https://lore.kernel.org/r/20260522172219.1423324-5-tj@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
The existing kernel-side export of bpf_arena_alloc_pages is _non_sleepable
only - it's used by the verifier to inline the kfunc when the call site is
non-sleepable. There is no sleepable equivalent for kernel callers. The
kfunc bpf_arena_alloc_pages itself is BPF-only.
sched_ext needs sleepable kernel-side allocs for its arena pool init/grow
paths. Add bpf_arena_alloc_pages_sleepable() mirroring the _non_sleepable
wrapper but passing sleepable=true to arena_alloc_pages().
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Emil Tsalapatis <emil@etsalapatis.com>
Link: https://lore.kernel.org/r/20260522172219.1423324-4-tj@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
BPF arena usage is becoming more prevalent, but kernel <-> BPF communication
over arena memory is awkward today. Data has to be staged through a trusted
kernel pointer with extra code and copying on the BPF side. While reads
through arena pointers can use a fault-safe helper, writes don't have a good
solution. The in-line alternative would need instruction emulation or asm
fixup labels.
Enable direct kernel-side reads and writes within GUARD_SZ / 2 of any
handed-in arena pointer, without bounds checking. A per-arena scratch page
is installed by the arch fault path into empty arena kernel PTEs - x86 from
page_fault_oops() for not-present faults, arm64 from __do_kernel_fault() for
translation faults, both after the existing exception-table and KFENCE
handling. The faulting instruction retries and the access is also reported
through the program's BPF stream, preserving error reporting.
bpf_prog_find_from_stack() resolves the current BPF program (and its arena)
from the kernel stack - no new bpf_run_ctx state is added. Recovery covers
the 4 GiB arena plus the upper half-guard (GUARD_SZ / 2). The lower
half-guard is excluded because well-behaved kfuncs only access forward from
arena pointers. The kfunc-author contract - access at most GUARD_SZ / 2 past
a handed-in pointer - is documented in Documentation/bpf/kfuncs.rst.
The install is lock-free via ptep_try_set(). On race-loss the winning
installer's PTE is already valid, so the access retry succeeds. The arena
clear path uses ptep_get_and_clear() so installer and clearer race through
atomic accessors. No flush_tlb_kernel_range() afterwards. Stale "not mapped"
entries just cause one extra re-fault, cheaper than a global IPI on every
install.
Scratch exists only to keep the kernel from oopsing on an in-line arena
access. Its presence at a PTE means the BPF program has already
malfunctioned, and the violation is reported through the program's BPF
stream. The only requirement for behavior on a scratched PTE is that the
kernel doesn't crash. In particular, any user-side access through such a PTE
may segfault. The shared scratch page is freed once during map destruction.
BPF instruction faults continue to use the existing JIT exception-table
path. This patch changes only the kernel-text fault path. No UAPI flag is
added. The new behavior is the default.
v2: Use ptep_get_and_clear() in apply_range_clear_cb(). (David)
v3: Stub bpf_arena_handle_page_fault() for !CONFIG_BPF_SYSCALL. (lkp)
Suggested-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Emil Tsalapatis <emil@etsalapatis.com>
Cc: David Hildenbrand <david@kernel.org>
Link: https://lore.kernel.org/r/20260522172219.1423324-3-tj@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
- Spurious WARN in ops_dequeue() racing with concurrent dispatch.
- Self-deadlock between scheduler disable and a concurrent sub-sched
enable.
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Merge tag 'sched_ext-for-7.1-rc4-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/sched_ext
Pull sched_ext fixes from Tejun Heo:
- Spurious WARN in ops_dequeue() racing with concurrent dispatch
- Self-deadlock between scheduler disable and a concurrent sub-sched
enable
* tag 'sched_ext-for-7.1-rc4-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/sched_ext:
sched_ext: Fix spurious WARN on stale ops_state in ops_dequeue()
sched_ext: Fix deadlock between scx_root_disable() and concurrent forks
Two rstat fixes:
- Out-of-bounds access in the css_rstat_updated() BPF kfunc when called
with an unchecked user-supplied cpu.
- Over-strict NMI guard after the recent switch to try_cmpxchg left
sparc and ppc64 unable to queue rstat updates from NMI.
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Merge tag 'cgroup-for-7.1-rc4-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup
Pull cgroup fixes from Tejun Heo:
"Two rstat fixes:
- Out-of-bounds access in the css_rstat_updated() BPF kfunc when
called with an unchecked user-supplied cpu
- Over-strict NMI guard after the recent switch to try_cmpxchg left
sparc and ppc64 unable to queue rstat updates from NMI"
* tag 'cgroup-for-7.1-rc4-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
cgroup: rstat: relax NMI guard after switch to try_cmpxchg
cgroup/rstat: validate cpu before css_rstat_cpu() access
When a multi-threaded process receives a stop signal (e.g., SIGSTOP),
do_signal_stop() sets JOBCTL_STOP_PENDING and JOBCTL_STOP_CONSUME on all
threads and sets signal->group_stop_count to the number of threads. If
one of the threads concurrently calls execve(), de_thread() invokes
zap_other_threads() to kill all other threads. zap_other_threads()
aborts the pending group stop by resetting signal->group_stop_count to 0
and clears the JOBCTL_PENDING_MASK for all other threads. However, it
fails to clear the job control flags for the calling thread.
When execve() completes, the calling thread returns to user mode and
checks for pending signals. Seeing the stale JOBCTL_STOP_PENDING flag,
it calls do_signal_stop(), which invokes task_participate_group_stop().
Since JOBCTL_STOP_CONSUME is still set, it attempts to decrement the
already-zero signal->group_stop_count, triggering a warning:
sig->group_stop_count == 0
WARNING: CPU: 1 PID: 6475 at kernel/signal.c:373
task_participate_group_stop+0x215/0x2d0
Call Trace:
<TASK>
do_signal_stop+0x3be/0x5c0 kernel/signal.c:2619
get_signal+0xa8c/0x1330 kernel/signal.c:2884
arch_do_signal_or_restart+0xbc/0x840 arch/x86/kernel/signal.c:337
exit_to_user_mode_loop+0x8c/0x4d0 kernel/entry/common.c:98
do_syscall_64+0x33e/0xf80 arch/x86/entry/syscall_64.c:100
entry_SYSCALL_64_after_hwframe+0x77/0x7f
</TASK>
Fix this race condition by clearing the JOBCTL_PENDING_MASK for the
calling thread in zap_other_threads(), ensuring it does not retain any
stale job control state after the thread group is destroyed. This aligns
with other functions that tear down a thread group and abort group
stops, such as zap_process() and complete_signal(), which correctly
clear these flags for all threads including the current one.
Fixes: 39efa3ef3a ("signal: Use GROUP_STOP_PENDING to stop once for a single group stop")
Assisted-by: Gemini:gemini-3.1-pro-preview Gemini:gemini-3-flash-preview syzbot
Reported-by: syzbot+b109633ea805cac54a61@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=b109633ea805cac54a61
Link: https://syzkaller.appspot.com/ai_job?id=d70208cc-862b-4fe3-bf02-3031e10cd0b3
Signed-off-by: Aleksandr Nogikh <nogikh@google.com>
Link: https://patch.msgid.link/20260521142240.2973022-1-nogikh@google.com
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
Two minor updates for the DMA-mapping code, mainly fixing some rare
corner cases (Petr Tesarik, Jianpeng Chang).
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Merge tag 'dma-mapping-7.1-2026-05-22' of git://git.kernel.org/pub/scm/linux/kernel/git/mszyprowski/linux
Pull dma-mapping fixes from Marek Szyprowski:
"Two minor updates for the DMA-mapping code, mainly fixing some rare
corner cases (Petr Tesarik, Jianpeng Chang)"
* tag 'dma-mapping-7.1-2026-05-22' of git://git.kernel.org/pub/scm/linux/kernel/git/mszyprowski/linux:
dma-mapping: move dma_map_resource() sanity check into debug code
dma-direct: fix use of max_pfn
- Avoid NULL return from hist_field_name()
The function hist_field_name() is directly passed to a strcat()
which does not handle "NULL" characters. Return a zero length
string when size is greater than the limit.
This is used only to output already created histograms and no
field currently is greater than the limit. But it should still
not return NULL.
- Do not call map->ops->elt_free() on allocation failure
When elt_alloc() fails, it should not call the map->ops->elt_free()
function if it exists, as that function may not be able to handle
the free on allocation failures. The ->elt_free() should only be
called when elt_alloc() succeeds.
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Merge tag 'trace-v7.1-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace
Pull tracing fixes from Steven Rostedt:
- Avoid NULL return from hist_field_name()
The function hist_field_name() is directly passed to a strcat() which
does not handle "NULL" characters. Return a zero length string when
size is greater than the limit.
This is used only to output already created histograms and no field
currently is greater than the limit. But it should still not return
NULL.
- Do not call map->ops->elt_free() on allocation failure
When elt_alloc() fails, it should not call the map->ops->elt_free()
function if it exists, as that function may not be able to handle the
free on allocation failures. The ->elt_free() should only be called
when elt_alloc() succeeds.
* tag 'trace-v7.1-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
tracing: Do not call map->ops->elt_free() if elt_alloc() fails
tracing: Avoid NULL return from hist_field_name() on truncation
There was a report on a multi-numa-nodes arm64 server that when IOMMU
is disabled, the dma_alloc_coherent() function always returns memory
from node 0 even for devices attaching to other nodes, while they can
get local dma memory when IOMMU is on with the same API.
The reason is, when IOMMU is disabled, the dma_alloc_coherent() will
go the direct way and call dma_alloc_contiguous(). The system doesn't
have any explicit cma setting (like per-numa cma), and only has a
default 64MB cma reserved area (on node 0), where kernel will try
first to allocate memory from.
Robin Murphy suggested to setup pernuma cma or disable cma, which did
solve the issue. While there is still concern that for customers
which don't have much kernel knowledge, they could still suffer from
this silently as some architectures enable cma area by default (not
an issue for X86 though, which set CONFIG_CMA_SIZE_MBYTES to 0 by
default) for most Linux distributions.
One thought is to follow the current cma reserving policy for platform
with 'CONFIG_DMA_NUMA_CMA=y', that if the numa cma (either the 'numa cma'
or 'cma pernuma' method) is not explicitly configured, and the platform
really has multiple NUMA nodes, set it up according to size of default
'dma_contiguous_default_area'. This way, the default behavior of
platform with one NUMA node is kept unchanged (say embedded/small
devices don't need to allocate extra memory), while the general dma
locality is improved.
Add a new bool kernel config CONFIG_CMA_SIZE_PERNUMA to control whether
to enable it. Even when the config is enabled, user can still disable
it by kernel-cmdline setting like "numa_cma=0:0" or "cma_pernuma=0".
Reported-by: Changrong Chen <chenchangrong.ccr@alibaba-inc.com>
Suggested-by: Ying Huang <ying.huang@linux.alibaba.com>
Suggested-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Feng Tang <feng.tang@linux.alibaba.com>
Link: https://lore.kernel.org/r/20260512085509.83002-1-feng.tang@linux.alibaba.com
Link: https://lore.kernel.org/all/20260520222742.GA1607511@ax162/
[mszyprow: squashed changes from both links, added __initdata attribute
to the numa_cma_configured variable]
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
When a child process exits, it sends exit_signal to its parent via
do_notify_parent(). The clone() syscall constructs exit_signal as:
(lower_32_bits(clone_flags) & CSIGNAL)
CSIGNAL is 0xff, so values in the range 65-255 are possible. However,
valid_signal() only accepts signals up to _NSIG (64 on x86_64). A
non-zero non-valid exit_signal acts the same as exit_signal == 0: the
parent process is not signaled when the child terminates.
The syzkaller reproducer triggers this by calling clone() with flags=0x80,
resulting in exit_signal = (0x80 & CSIGNAL) = 128, which exceeds _NSIG and
is not a valid signal.
The v1 of this patch added the check only in the clone() syscall handler,
which is incomplete. kernel_clone() has other callers such as
sys_ia32_clone() which would remain unprotected. Move the check to
kernel_clone() to cover all callers.
Since the valid_signal() check is now in kernel_clone() and covers all
callers including clone3(), the same check in copy_clone_args_from_user()
becomes redundant and is removed. The higher 32bits check for clone3() is
kept as it is clone3() specific.
Note that this is a user-visible change: previously, passing an invalid
exit_signal to clone() was silently accepted. The man page for clone()
does not document any defined behavior for invalid exit_signal values, so
rejecting them with -EINVAL is the correct behavior. It is unlikely that
any sane application relies on passing an invalid exit_signal.
[oleg@redhat.com: the comment above kernel_clone() should be updated]
Link: https://lore.kernel.org/abwvgU17W8wuW2-J@redhat.com
Link: https://lore.kernel.org/20260316151956.563558-1-kartikey406@gmail.com
Fixes: 3f2c788a13 ("fork: prevent accidental access to clone3 features")
Signed-off-by: Deepanshu Kartikey <Kartikey406@gmail.com>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Reported-by: syzbot+bbe6b99feefc3a0842de@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=bbe6b99feefc3a0842de
Tested-by: syzbot+bbe6b99feefc3a0842de@syzkaller.appspotmail.com
Link: https://lore.kernel.org/all/20260307064202.353405-1-kartikey406@gmail.com/T/ [v1]
Link: https://lore.kernel.org/all/20260316104536.558108-1-kartikey406@gmail.com/T/ [v2]
Acked-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Ben Segall <bsegall@google.com>
Cc: Christian Brauner <brauner@kernel.org>
Cc: David Hildenbrand <david@kernel.org>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Kees Cook <kees@kernel.org>
Cc: Liam Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes (Oracle) <ljs@kernel.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Valentin Schneider <vschneid@redhat.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
trace_iterator_increment() is only called from trace_find_next_entry_inc().
It's a small enough function that really doesn't need to be separated.
Move the code from trace_iterator_increment() into
trace_find_next_entry_inc() and remove trace_iterator_increment().
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Link: https://patch.msgid.link/20260521095026.20c9799d@gandalf.local.home
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Change to a flexible array member to allocate together with the array
struct.
Simplifies code slightly by removing no longer correct null checks for
pages and removing kfrees.
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Kees Cook <kees@kernel.org>
Cc: "Gustavo A. R. Silva" <gustavoars@kernel.org>
Link: https://patch.msgid.link/20260520215006.12008-1-rosenp@gmail.com
Signed-off-by: Rosen Penev <rosenp@gmail.com>
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
The events/ prefix should be removed, since synthetic_events
is now directly under the tracing root directory.
Cc: <mhiramat@kernel.org>
Cc: <mathieu.desnoyers@efficios.com>
Link: https://patch.msgid.link/20260521015211.111-1-ao.sun@transsion.com
Signed-off-by: Ao Sun <ao.sun@transsion.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Use krealloc_array() when growing tr->topts instead of open-coding the
size calculation in krealloc().
This makes the resize path use the helper intended for array allocations
and avoids manual multiplication of the element count and element size.
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Link: https://patch.msgid.link/20260519083409.3885032-1-pengyu@kylinos.cn
Signed-off-by: Yu Peng <pengyu@kylinos.cn>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Use pr_warn() instead of printk(KERN_WARNING ...) for the branch tracer
warning messages.
Keep the message text unchanged. The change only removes the open-coded
log level from these warnings.
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Link: https://patch.msgid.link/20260519081620.3874441-1-pengyu@kylinos.cn
Signed-off-by: Yu Peng <pengyu@kylinos.cn>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Currently, perf can not enable synthetic events. When it does, it either
causes a warning in the kernel or errors with "no such device".
Add the necessary code to allow perf to also attach to synthetic events.
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://patch.msgid.link/20260513150007.3b280e87@gandalf.local.home
Reported-by: Ian Rogers <irogers@google.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
The synthetic field helpers build a prefixed synthetic variable name and
a generated hist command in fixed MAX_FILTER_STR_VAL buffers. The
current code appends those strings with raw strcat(), so long key lists,
field names, or saved filters can run past the end of the staging
buffers.
Build both strings with seq_buf and propagate -E2BIG if either the
synthetic variable name or the generated command exceeds
MAX_FILTER_STR_VAL. This keeps the existing tracing-side limit while
using the helper intended for bounded command construction.
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Tom Zanussi <tom.zanussi@linux.intel.com>
Link: https://patch.msgid.link/20260430043350.57928-1-pengpeng@iscas.ac.cn
Fixes: 02205a6752 ("tracing: Add support for 'field variables'")
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Reviewed-by: Tom Zanussi <zanussi@kernel.org>
Signed-off-by: Pengpeng Hou <pengpeng@iscas.ac.cn>
[ sdr: Moved struct seq_buf *s for upside-down x-mas tree formatting ]
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
in trace_pipe_open() already check the IS_ERR(iter) and return early on
error,so iter after will be valid and it is safe to return 0 at end.
Link: https://patch.msgid.link/20260420101236.223919-1-yashsuthar983@gmail.com
Signed-off-by: Yash Suthar <yashsuthar983@gmail.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
- Fix reporting MISSED EVENTS in trace iterator
When the "trace" file is read with tracing enabled, if the writer
were to pass the iterator reader, it resets, sets a "missed_events"
flag and continues. The tracing output checks for missed events and
if there are some, it prints out "[LOST EVENTS]" to let the user
know events were dropped.
But the clearing of the missed_events happened when the tracing system
queried the ring buffer iterator about missed events. This was premature
as the ring buffer is per CPU, and the tracing code reads all the
CPU buffers and checks for missed events when it is read. If the
CPU iterator that had missed events isn't printed next, the output
for the LOST EVENTS is lost.
Clear the missed_events flag when the iterator moves to the next event
and not when the missed_events flag is queried. Also clear it on reset.
- Flush and stop the persistent ring buffer on panic
On panic the persistent ring buffer is used to debug what caused the
panic. But on some architectures, it requires flushing the memory
from cache, otherwise, the ring buffer persistent memory may not have
the last events and this could also cause the ring buffer to be
corrupted on the next boot.
- Fix nr_subbufs initialization in simple_ring_buffer_init_mm
The remote simple ring buffer meta data nr_subbufs is initialized
too early and gets cleared later on, making it zero and not reflect
the actual number of sub-buffers.
- Fix unload_page for simple_ring_buffer init rollback
On error, the pages loaded need to be unloaded. To unload a page
it is expected that: page = load_page(va); -> unload_page(page).
But the code was doing: unload_page(va) and not unload_page(page).
- Create output file from cmd_check_undefined
The check for undefined symbols checks if the file *.o.checked exists
and if so it skips doing the work. But the *.o.checked file never
was created making every build do the work even when it was already
done previously.
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Merge tag 'trace-ringbuffer-v7.1-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace
Pull ring-buffer fixes from Steven Rostedt:
- Fix reporting MISSED EVENTS in trace iterator
When the "trace" file is read with tracing enabled, if the writer
were to pass the iterator reader, it resets, sets a "missed_events"
flag and continues. The tracing output checks for missed events and
if there are some, it prints out "[LOST EVENTS]" to let the user know
events were dropped.
But the clearing of the missed_events happened when the tracing
system queried the ring buffer iterator about missed events. This was
premature as the ring buffer is per CPU, and the tracing code reads
all the CPU buffers and checks for missed events when it is read. If
the CPU iterator that had missed events isn't printed next, the
output for the LOST EVENTS is lost.
Clear the missed_events flag when the iterator moves to the next
event and not when the missed_events flag is queried. Also clear it
on reset.
- Flush and stop the persistent ring buffer on panic
On panic the persistent ring buffer is used to debug what caused the
panic. But on some architectures, it requires flushing the memory
from cache, otherwise, the ring buffer persistent memory may not have
the last events and this could also cause the ring buffer to be
corrupted on the next boot.
- Fix nr_subbufs initialization in simple_ring_buffer_init_mm
The remote simple ring buffer meta data nr_subbufs is initialized too
early and gets cleared later on, making it zero and not reflect the
actual number of sub-buffers.
- Fix unload_page for simple_ring_buffer init rollback
On error, the pages loaded need to be unloaded. To unload a page it
is expected that: page = load_page(va); -> unload_page(page). But the
code was doing: unload_page(va) and not unload_page(page).
- Create output file from cmd_check_undefined
The check for undefined symbols checks if the file *.o.checked exists
and if so it skips doing the work. But the *.o.checked file never was
created making every build do the work even when it was already done
previously.
* tag 'trace-ringbuffer-v7.1-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
tracing: Create output file from cmd_check_undefined
tracing: Fix unload_page for simple_ring_buffer init rollback
tracing: Fix nr_subbufs initialization in simple_ring_buffer_init_mm()
ring-buffer: Flush and stop persistent ring buffer on panic
ring-buffer: Fix reporting of missed events in iterator
ops_dequeue() can race with finish_dispatch() and spuriously trigger the
"queued task must be in BPF scheduler's custody" warning.
ops_dequeue() snapshots p->scx.ops_state via atomic_long_read_acquire()
and then, in the SCX_OPSS_QUEUED arm, asserts that SCX_TASK_IN_CUSTODY
is set. The two reads are not atomic w.r.t. a concurrent
finish_dispatch() running on another CPU:
CPU 1 CPU 2
===== =====
dequeue_task_scx()
ops_dequeue()
opss = read_acquire(ops_state)
= SCX_OPSS_QUEUED
finish_dispatch()
cmpxchg ops_state:
SCX_OPSS_QUEUED -> SCX_OPSS_DISPATCHING [succeeds]
dispatch_enqueue(SCX_DSQ_GLOBAL,
SCX_ENQ_CLEAR_OPSS)
call_task_dequeue()
p->scx.flags &= ~SCX_TASK_IN_CUSTODY
WARN_ON_ONCE(!(p->scx.flags &
SCX_TASK_IN_CUSTODY))
/* opss is stale: QUEUED,
* but task already claimed */
set_release(ops_state, SCX_OPSS_NONE)
The race has been observed via two distinct call chains: the most common
goes through sched_setaffinity(), a rarer variant through
sched_change_begin().
For SCX_DSQ_GLOBAL / SCX_DSQ_BYPASS, dispatch_enqueue() clears
SCX_TASK_IN_CUSTODY before clearing ops_state to SCX_OPSS_NONE
(intentional, to avoid concurrent non-atomic RMW of p->scx.flags against
ops_dequeue()). The window between those two writes is exactly what
ops_dequeue() observes as "QUEUED without custody".
The observed state is not actually inconsistent, it just means CPU 1 has
already claimed the task and the QUEUED value held by CPU 2 is stale.
Re-read ops_state in that case; the next read is guaranteed to return
SCX_OPSS_DISPATCHING or SCX_OPSS_NONE, both of which exit the switch
cleanly. The retry is bounded: once IN_CUSTODY is cleared, ops_state has
already advanced past QUEUED for this dispatch cycle, and a fresh QUEUED
would require re-enqueue under p's rq lock, which CPU 2 holds.
Changes in v2:
- Use READ_ONCE() for p->scx.flags to ensure fresh reads and prevent
compiler reordering in the lockless path
- Add cpu_relax() to reduce power consumption and improve performance
during the spin-wait
- Use unlikely() to optimize branch prediction for the common case
- Expand the in-code comment to document the race condition and
bounded retry guarantee
Fixes: ebf1ccff79 ("sched_ext: Fix ops.dequeue() semantics")
Suggested-by: Andrea Righi <arighi@nvidia.com>
Signed-off-by: Samuele Mariotti <smariotti@disroot.org>
Signed-off-by: Paolo Valente <paolo.valente@unimore.it>
Signed-off-by: Tejun Heo <tj@kernel.org>
In paths where tracing_map_elt_alloc() failed to allocate objects,
the map->ops->elt_alloc() call was never successful. In this case,
map->ops->elt_free() should not be called.
Link: https://sashiko.dev/#/patchset/20260520223101.34710-1-rosenp%40gmail.com
Cc: stable@vger.kernel.org
Cc: Tom Zanussi <tom.zanussi@linux.intel.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Rosen Penev <rosenp@gmail.com>
Reported-by: Sashiko <sashiko-bot@kernel.org>
Fixes: 2734b62952 ("tracing: Add per-element variable support to tracing_map")
Link: https://patch.msgid.link/177933895460.108746.5396070821443932634.stgit@devnote2
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
As the output file is currently never created, the check will run every
time, even if the inputs have not changed.
Create an empty output file which allows make to skip the execution when
it is not necessary.
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Vincent Donnefort <vdonnefort@google.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Link: https://patch.msgid.link/20260520-tracing-ringbuffer-check-v1-1-d979cfab1338@weissschuh.net
Fixes: 1211907ac0 ("tracing: Generate undef symbols allowlist for simple_ring_buffer")
Fixes: 58b4bd1839 ("tracing: Adjust cmd_check_undefined to show unexpected undefined symbols")
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Tested-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
The unload_page callback expects the return value of load_page() as its
argument: ret = load_page(va); unload(ret). Fix the rollback code in
simple_ring_buffer_init_mm() where the descriptor's VA is used instead
of the loaded page address.
Link: https://patch.msgid.link/20260512141614.1759430-1-vdonnefort@google.com
Fixes: 635923081c ("tracing: load/unload page callbacks for simple_ring_buffer")
Signed-off-by: Vincent Donnefort <vdonnefort@google.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
nr_subbufs in the ring buffer metadata is always initialized to zero
because it is assigned from cpu_buffer->nr_pages before the page
initialization loop has run. While nr_subbufs is not currently read
by the kernel, it should reflect the actual buffer geometry in the
meta page for correctness.
Move the assignment after the page loop so that cpu_buffer->nr_pages
holds the final count.
Link: https://patch.msgid.link/20260512135420.99194-1-devnexen@gmail.com
Fixes: 34e5b958bd ("tracing: Introduce simple_ring_buffer")
Reviewed-by: Vincent Donnefort <vdonnefort@google.com>
Assisted-by: Claude:claude-opus-4-7
Signed-off-by: David Carlier <devnexen@gmail.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
On real hardware, panic and machine reboot may not flush hardware cache
to memory. This means the persistent ring buffer, which relies on a
coherent state of memory, may not have its events written to the buffer
and they may be lost. Moreover, there may be inconsistency with the
counters which are used for validation of the integrity of the
persistent ring buffer which may cause all data to be discarded.
To avoid this issue, stop recording of the ring buffer on panic and
flush the cache of the ring buffer's memory.
Fixes: e645535a95 ("tracing: Add option to use memmapped memory for trace boot instance")
Cc: stable@vger.kernel.org
Cc: Will Deacon <will@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Ian Rogers <irogers@google.com>
Link: https://patch.msgid.link/177751969602.2136606.12031934362587643488.stgit@mhiramat.tok.corp.google.com
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
When tracing is active while reading the trace file, if the iterator
reading the buffer detects that the writer has passed the iterator head,
it will reset and set a "missed events" flag. This flag is passed to the
output processing to show the user that events were missed:
CPU:4 [LOST EVENTS]
The problem is that the flag is reset after it is checked in
ring_buffer_iter_dropped(). But the "trace" file iterates over all the CPU
ring buffers and it will check if they are dropped when figuring out which
buffer to print next. This prematurely clears the missed_events flag if
the CPU buffer with the missed events is not the one that is printed next.
On the iteration where the CPU buffer with the missed events is printed,
the check if it had missed events would return false and the output does
not show that events were missed.
Do not reset the missed_events flag when checking if there were missed
events, but instead clear it when moving the iterator head to the next
event.
Cc: stable@vger.kernel.org
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Link: https://patch.msgid.link/20260520220801.4fd09d13@fedora
Fixes: c9b7a4a72f ("ring-buffer/tracing: Have iterator acknowledge dropped events")
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Add three kfuncs for BPF linked list queries:
- bpf_list_is_first(head, node): true if node is the first in the list.
- bpf_list_is_last(head, node): true if node is the last in the list.
- bpf_list_empty(head): true if the list has no entries.
Currently, without these kfuncs, to implement the above functionality
it is necessary to first call bpf_list_pop_front/back to retrieve the
first or last node before checking whether the passed-in node was the
first or last one. After the check, the node had to be pushed back into
the list using bpf_list_push_front/back, which was very inefficient.
Now, with the bpf_list_is_first/last/empty kfuncs, we can directly
check whether a node is the first, last, or whether the list is empty,
without having to first retrieve the node.
Signed-off-by: Kaitao Cheng <chengkaitao@kylinos.cn>
Reviewed-by: Emil Tsalapatis <emil@etsalapatis.com>
Link: https://lore.kernel.org/r/20260521032306.97118-8-kaitao.cheng@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Add a new kfunc bpf_list_add(head, new, prev, meta, off) that
inserts 'new' after 'prev' in the BPF linked list. Both must be in
the same list; 'prev' must already be in the list. The new node must
be an owning reference (e.g. from bpf_obj_new); the kfunc consumes
that reference and the node becomes non-owning once inserted.
We have added an additional parameter bpf_list_head *head to
bpf_list_add, as the verifier requires the head parameter to
check whether the lock is being held.
Returns 0 on success, -EINVAL if 'prev' is not in a list or 'new'
is already in a list (or duplicate insertion). On failure, the
kernel drops the passed-in node.
Signed-off-by: Kaitao Cheng <chengkaitao@kylinos.cn>
Reviewed-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20260521032306.97118-7-kaitao.cheng@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Refactor __bpf_list_add to accept (node, head, struct list_head **prev_ptr,
..) instead of (node, head, bool tail, ..). Load prev from *prev_ptr after
INIT_LIST_HEAD(h), so we never dereference an uninitialized h->prev when
head was 0-initialized (e.g. push_back passes &h->prev).
When prev is not the list head, validate that prev is in the list via
its owner.
Prepares for bpf_list_add(head, new, prev, ..) to insert after a given
list node.
Signed-off-by: Kaitao Cheng <chengkaitao@kylinos.cn>
Reviewed-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20260521032306.97118-6-kaitao.cheng@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Allow users to remove any node from a linked list.
We have added an additional parameter bpf_list_head *head to
bpf_list_del, as the verifier requires the head parameter to
check whether the lock is being held.
Signed-off-by: Kaitao Cheng <chengkaitao@kylinos.cn>
Reviewed-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20260521032306.97118-5-kaitao.cheng@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
KF_ARG_PTR_TO_LIST_NODE normally requires an owning reference
(PTR_TO_BTF_ID | MEM_ALLOC with ref_obj_id). Introduce the
__nonown_allowed annotation on selected list-node arguments so
non-owning references with ref_obj_id==0 are accepted as well.
This patch only adds the generic verifier support and documents the
annotation. Later patches in the series will apply it to bpf_list_add
/del(), and bpf_list_is_first/last(), allowing bpf_list_front/back()
results to be used as the insertion point, deletion target, or query
target for those kfuncs.
Verifier keeps existing owning-ref checks by default; only arguments
annotated with __nonown_allowed bypass MEM_ALLOC/ref_obj_id checks
and then follow the same list-node validation path.
Signed-off-by: Kaitao Cheng <chengkaitao@kylinos.cn>
Reviewed-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20260521032306.97118-4-kaitao.cheng@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
The issue only becomes exposed once bpf_list_del() is available: callers
can pass an arbitrary bpf_list_head and bpf_list_node pair, including
nodes that are not actually linked to the supplied head, or nodes that
outlive their original head after refcount-based retention. This was
not practically reachable for callers restricted to pop-style helpers
alone; bpf_list_del() widens the API surface.
A failure mode appears when bpf_list_head_free() runs while a program
still holds an independent refcount on a node (for example via
bpf_refcount_acquire()). The list head value embedded in map memory can
go away while the node object survives. If node->owner is left pointing
at the old head address until drop completes, that pointer becomes stale.
If a new bpf_list_head is later allocated at the same address and the
stale node is passed to bpf_list_del(), the owner comparison can succeed
even though the node is not really linked to the new head, and
list_del_init() will follow bogus next/prev pointers with the risk of
memory corruption.
When draining a bpf_list_head, mark each node owner with BPF_PTR_POISON
under the map spinlock while moving it to a private drain list, then
list_del_init() the node and clear owner to NULL before calling
__bpf_obj_drop_impl(). Concurrent readers therefore never observe a
node that appears linked to a head while its list_head is inconsistent,
and surviving refcounted nodes never retain a stale non-NULL owner.
Signed-off-by: Kaitao Cheng <chengkaitao@kylinos.cn>
Link: https://lore.kernel.org/r/20260521032306.97118-3-kaitao.cheng@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Refactor __bpf_list_del to accept (head, struct list_head *n) instead of
(head, bool tail). The caller now passes the specific node to remove:
bpf_list_pop_front passes h->next, bpf_list_pop_back passes h->prev.
Prepares for introducing bpf_list_del(head, node) kfunc to remove an
arbitrary node when the user holds ownership.
Signed-off-by: Kaitao Cheng <chengkaitao@kylinos.cn>
Reviewed-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20260521032306.97118-2-kaitao.cheng@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Sub-sched cap code and other upcoming consumers need bulk cmask ops, both
mutating (and/or/copy/andnot) and predicate (subset/intersects/empty).
cmask_walk_op2() walks the intersection of two ranges word by word;
cmask_walk_op1() walks one range. Both are __always_inline and dispatched on
a compile-time-constant op enum, so each public entry collapses to a
specialized loop with the inner switch reduced to one arm.
Two-cmask ops only touch bits in the intersection of the two ranges; bits
outside are left unchanged. scx_cmask_or_racy() and scx_cmask_copy_racy()
mirror the locking forms but read @src word-by-word through data_race();
callers handle ordering with concurrent writers themselves.
v2: Add scx_cmask_empty().
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Andrea Righi <arighi@nvidia.com>
scx_cmask carries @base and @nr_cids but not the bits[] allocation size, so
helpers reshaping the active range have no way to check it fits and later
kfuncs taking caller-provided storage can't validate it.
Add @alloc_words (u64 word count) annotated with __counted_by, and split the
bit-range API into three helpers:
- SCX_CMASK_DEFINE() / __SCX_CMASK_DEFINE() define an on-stack cmask, the
latter taking an explicit capacity for oversized storage.
SCX_CMASK_DEFINE_SHARD() is a thin wrapper that always reserves
SCX_CID_SHARD_MAX_CPUS bits of storage.
- scx_cmask_init() / __scx_cmask_init() initialize a cmask, with the same
tight-vs-explicit split.
- scx_cmask_reframe() reshapes the active range without resizing storage.
The BPF mirror (cmask_init / __cmask_init / cmask_reframe) gets the same
shape.
Add scx_cmask_clear() and scx_cmask_fill() to zero and set the
active-range bits respectively. scx_cpumask_to_cmask() uses
scx_cmask_clear(); scx_cmask_init() would otherwise re-write @alloc_words
on every call.
A later patch uses @alloc_words in scx_cmask_ref_shard() to refuse output
storage that can't hold the requested shard.
v2: Init per-CPU scx_set_cmask_scratch (was zero-init, emitted empty
cmasks). Add nr_cids/alloc_cids check in BPF __cmask_init().
(sashiko AI)
Widen SCX_CMASK_NR_WORDS()/CMASK_NR_WORDS() to compute in u64 so that
@nr_cids near U32_MAX no longer wraps to a small value and bypasses
the bounds check in cmask_reframe(). (Andrea)
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Andrea Righi <arighi@nvidia.com>
struct scx_cmask is a base-windowed bitmap over cid space. Each bit
represents one cid, so the count of active bits is the count of cids. The
sibling struct scx_cid_shard already uses nr_cids. Rename as a prep so the
following patches that grow the cmask API can use the consistent name.
v2: Also rename src->nr_bits / dst->nr_bits in
cmask_copy_from_kernel(). (sashiko AI)
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Andrea Righi <arighi@nvidia.com>
Dump the saved IRQ stack trace regardless of whether the event was
THREAD_CONTEXT or THREAD_URET.
In the uret case, the latency presumably had not yet crossed the
threshold at IRQ time (or else it would have dumped the stack at thread
wakeup time, unless we're racing with a change to the threshold), but it
may have at least contributed -- and this is possible with THREAD_CONTEXT
as well.
In any case, it helps with writing reliable rtla tests if we always get
a stack trace on a threshold event.
Cc: John Kacur <jkacur@redhat.com>
Cc: Tomas Glozar <tglozar@redhat.com>
Cc: Costa Shulyupin <costa.shul@redhat.com>
Cc: Wander Lairson Costa <wander@redhat.com>
Link: https://patch.msgid.link/20260511223143.1477332-1-crwood@redhat.com
Signed-off-by: Crystal Wood <crwood@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Certain drivers release resources (pinned pages, etc.) into system
memory during the prepare freeze PM op, making them swappable.
Currently, hibernate_preallocate_memory() is called before prepare
freeze, so those drivers have no opportunity to release resources
first. If a driver is holding a large amount of unswappable system
RAM, this can cause hibernate_preallocate_memory() to fail.
Move the call to hibernate_preallocate_memory() after prepare freeze.
According to the documentation for the prepare callback, devices should
be left in a usable state, so storage drivers should still be able to
service I/O requests. This allows drivers to release unswappable
resources prior to preallocation, so they can be swapped out through
hibernate_preallocate_memory()'s reclaim path.
Also remove shrink_shmem_memory() since hibernate_preallocate_memory()
will have reclaimed enough memory for the hibernation image.
Signed-off-by: Matthew Leach <matthew.leach@collabora.com>
Reviewed-by: Mario Limonciello (AMD) <superm1@kernel.org>
[ rjw: Subject and changelog tweaks ]
Link: https://patch.msgid.link/20260403-hibernation-fixes-v3-1-31bc9fa3ba2d@collabora.com
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
hist_field_name() returns "" everywhere except the fully-qualified
VAR_REF/EXPR case, where snprintf() truncation returns NULL early
and bypasses the bottom NULL->"" guard. Callers don't expect NULL:
strcat(expr, hist_field_name(field, 0)) at trace_events_hist.c:1758
and the strcmp() in the sort-key match loop at :4804 both deref it.
system and event_name are bounded by MAX_EVENT_NAME_LEN, but the
field name on a VAR_REF is kstrdup'd from a histogram variable
name parsed out of the trigger string and has no length cap, so
a long enough var name in a fully qualified reference can reach
the truncation path.
Keep the length check but leave field_name as "" on overflow.
Link: https://patch.msgid.link/20260508195747.25492-1-devnexen@gmail.com
Fixes: 5ec1d1e97d ("tracing: Rebuild full_name on each hist_field_name() call")
Signed-off-by: David Carlier <devnexen@gmail.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Commit 36df6e3dbd ("cgroup: make css_rstat_updated nmi safe") used
this_cpu_cmpxchg() for the lockless insertion, and therefore required
both ARCH_HAVE_NMI_SAFE_CMPXCHG and ARCH_HAS_NMI_SAFE_THIS_CPU_OPS in
the NMI guard: on archs without the latter, this_cpu_cmpxchg() falls
back to "local_irq_save() + plain cmpxchg", and local_irq_save()
cannot mask NMIs.
Commit 3309b63a22 ("cgroup: rstat: use LOCK CMPXCHG in
css_rstat_updated") later replaced this_cpu_cmpxchg() with plain
try_cmpxchg() to fix cross-CPU lockless-list corruption, but left the
NMI guard untouched. After that switch, css_rstat_updated() no longer
performs any this_cpu_*() RMW operations and only relies on the arch
having NMI-safe cmpxchg, so ARCH_HAS_NMI_SAFE_THIS_CPU_OPS is no
longer required in the guard.
Relax the guard accordingly so that archs which have HAVE_NMI and
ARCH_HAVE_NMI_SAFE_CMPXCHG but not ARCH_HAS_NMI_SAFE_THIS_CPU_OPS
(e.g. sparc, powerpc on PPC64/BOOK3S) can benefit from the existing
CONFIG_MEMCG_NMI_SAFETY_REQUIRES_ATOMIC path. Without this, the css
is never queued in NMI on those archs, and the atomics staged by
account_{slab,kmem}_nmi_safe() are not drained by flush_nmi_stats().
Fixes: 3309b63a22 ("cgroup: rstat: use LOCK CMPXCHG in css_rstat_updated")
Signed-off-by: Cunlong Li <shenxiaogll@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Fix a regression introduced by commit 61bbcfb505 ("srcu: Push
srcu_node allocation to GP when non-preemptible"): SRCU may queue works
on CPUs that are "possible" but never have been online. In such a case,
the work callbacks may not be executed until the corresponding CPU gets
online, and as the callbacks accumulates, workqueue lockups will fire.
Fix this by avoiding queuing works on CPUs that have never been online.
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Merge tag 'rcu-fixes.v7.1-20260519a' of git://git.kernel.org/pub/scm/linux/kernel/git/rcu/linux
Pull RCU fixes from Boqun Feng:
"Fix a regression introduced by commit 61bbcfb505 ("srcu: Push
srcu_node allocation to GP when non-preemptible").
SRCU may queue works on CPUs that are "possible" but never have been
online. In such a case, the work callbacks may not be executed until
the corresponding CPU gets online, and as the callbacks accumulates,
workqueue lockups will fire.
Fix this by avoiding queuing works on CPUs that have never been
online"
* tag 'rcu-fixes.v7.1-20260519a' of git://git.kernel.org/pub/scm/linux/kernel/git/rcu/linux:
srcu: Don't queue workqueue handlers to never-online CPUs
__bpf_dynptr_data() can return NULL (FILE dynptrs, any non-contiguous
backing). bpf_verify_pkcs7_signature() forwards the pointer to
verify_pkcs7_signature() unchecked, causing a NULL deref in
asn1_ber_decoder() reachable from a sleepable BPF LSM at lsm.s/bpf.
NULL-check both pointers and reject with -EINVAL. Mirrors the guards
already in kernel/bpf/crypto.c.
Fixes: 865b0566d8 ("bpf: Add bpf_verify_pkcs7_signature() kfunc")
Reported-by: Xianrui Dong <dongxianrui1@gmail.com>
Signed-off-by: KP Singh <kpsingh@kernel.org>
Reviewed-by: Amery Hung <ameryhung@gmail.com>
Acked-by: Song Liu <song@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20260520024059.313468-1-kpsingh@kernel.org
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Enable context analysis for struct rt_mutex and annotate all functions that
accept a struct rt_mutex pointer. In the __rt_mutex_lock_common() callers,
instead of adding the __no_context_analysis annotation, emit a runtime
warning if the __rt_mutex_lock_common() return value is not zero and add an
__acquire() statement.
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260508174520.1416285-1-bvanassche@acm.org
Recent optimizations of sd->shared assignment moved to allocating a
single instance of per-CPU sched_domain_shared objects per s_data.
Recent optimizations to select_idle_capacity() moved the sd->shared
assignments to "sd_asym" domain when ASYM_CPUCAPACITY is detected but
cache-aware scheduling mandates the presence of "sd_llc_shared" to
compute and cache per-LLC statistics.
Use an "alloc_flags" union in sched_domain_shared to claim a
sched_domain_shared object per sched_domain. Allocation starts searching
for an available / matching sched_domain_shared instance from the first
CPU of sched_domain_span(sd) (sd can be sd_llc, or sd_asym). If the
shared object is claimed by another domain, the instance corresponding
to next CPU in the domain span is explored until a matching / available
instance is found.
In case of a single CPU in sched_domain_span(), the domain will be
degenerated and a temporary overlap of ->shared objects across different
domains is acceptable.
"alloc_flags" forms a union with "nr_idle_scan" and the stale flags are
left as is when the sd->shared is published. The expectation is for the
first load balancing instance to correct the value just like the current
behavior, except the initial value is no longer 0.
Originally-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: K Prateek Nayak <kprateek.nayak@amd.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Andrea Righi <arighi@nvidia.com>
RT migration is done aggressively. When a CPU schedules out a high
priority RT task for a lower priority task, it will look to see if there's
any RT tasks that are waiting to run on another CPU that is of higher
priority than the task this CPU is about to run. If it finds one, it will
pull that task over to the CPU and allow it to run there instead.
Normally, this pulling is done by looking at the RT overloaded mask (rto)
which contains all the CPUs in the scheduler domain with RT tasks that are
waiting to run due to a higher priority RT task currently running on their
CPU. The CPU that is about to schedule a lower priority task will grab the
rq lock of the overloaded CPU and move the RT task from that CPU's runqueue
to the local one and schedule the higher priority RT task.
This caused issues when a lot of CPUs would schedule a lower priority task
at the same time. They would all try to grab the same runqueue lock of
the CPU with the overloaded RT tasks. Only the first CPU that got in will
get that task. All the others would wait until they got the runqueue lock
and see there's nothing to pull and do nothing. On systems with lots of
CPUs, this caused a large latency (up to 500us) which is beyond what
PREEMPT_RT is to allow.
The solution to that was to create an RT_PUSH_IPI logic. When any CPU
wanted to pull a task, instead of grabbing the runqueue lock of the
overloaded CPU, it would start by sending an IPI to the overloaded CPU,
and that IPI handler would have the CPU with the waiting RT task do a push
instead. Then that handler would send an IPI to the next CPU with
overloaded RT tasks, and so on. Note, after the first CPU starts this
process, if another CPU wanted to do a pull, it would see that the process
has already begun and would only increment a counter to have the IPIs
continue again.
The RT_PUSH_IPI solved the latency problem with PREEMPT_RT but could cause
a new issue with non PREEMPT_RT. Namely, softirqs run in a threaded
context on PREEMPT_RT but they can run in an interrupt context in non-RT.
If an IPI lands on a CPU that has just woken up multiple RT tasks and the
current CPU is running a non RT or a low priority RT task, instead of
doing a push, it would simply do a schedule on that CPU. But if a softirq
was also executing on this CPU, the schedule would need to wait until the
softirq finished. Until then, the CPU would still be considered overloaded
as there are RT tasks still waiting to run on it.
A live lock occurred on a workload that was doing heavy networking traffic
on a large machine where the softirqs would run 500us out of 750us. And it
would also be waking up RT tasks, causing the RT pull logic to be
constantly executed.
When a softirq triggered on a CPU with RT tasks queued but not running
yet, and the other CPUs would see this CPU as being overloaded, they would
send an IPI over to it. The CPU would notice that the waiting RT tasks are
of higher priority than the currently running task and simply schedule
that CPU instead. But because the softirq was executing, before it could
schedule, it would receive another IPI to do the same. The amount of IPIs
would slow down the currently running softirq so much that before it could
return back to task context, it would execute another softirq never
allowing the CPU to schedule. This live locked that CPU.
As RT_PUSH_IPI was created to help PREEMPT_RT, make it default off if
PREEMPT_RT is not enabled.
Fixes: b6366f048e ("sched/rt: Use IPI to trigger RT task push migration instead of pulling")
Closes: https://lore.kernel.org/all/20260506235716.2530720-1-tj@kernel.org/
Reported-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260515103740.25ccbed8@gandalf.local.home
K Prateek noticed we weren't setting the rq->next_class in
proxy_resched_idle(), when I was debugging an issue seen with
CONFIG_SCHED_PROXY_EXEC and some of Peter's new patches, and
suggested this fix.
So set rq->next_class when we temporarily switch the donor to
idle, so we don't accidentally call wakeup_preempt_fair()
with idle as the donor.
Suggested-by: K Prateek Nayak <kprateek.nayak@amd.com>
Signed-off-by: John Stultz <jstultz@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260514234732.3170197-1-jstultz@google.com
Add to select_idle_capacity() the same SIS_UTIL-controlled idle-scan
mechanism, already used by select_idle_cpu(): when sched_feat(SIS_UTIL)
is enabled and the LLC domain has sched_domain_shared data, derive the
per-attempt scan limit from sd->shared->nr_idle_scan.
That bounds the walk on large LLCs: once nr_idle_scan is exhausted,
return the best CPU seen so far. The early exit is gated on
!has_idle_core so an active idle-core search (SMT with idle cores
reported by test_idle_cores()) isn't cut short before it gets a chance
to find one.
Co-developed-by: Andrea Righi <arighi@nvidia.com>
Signed-off-by: Andrea Righi <arighi@nvidia.com>
Signed-off-by: K Prateek Nayak <kprateek.nayak@amd.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://patch.msgid.link/20260509180955.1840064-6-arighi@nvidia.com
When SD_ASYM_CPUCAPACITY load balancing considers pulling a misfit task,
capacity_of(dst_cpu) can overstate available compute if the SMT sibling is
busy: the core does not deliver its full nominal capacity.
If SMT is active and dst_cpu is not on a fully idle core, skip this
destination so we do not migrate a misfit expecting a capacity upgrade we
cannot actually provide.
Reported-by: Felix Abecassis <fabecassis@nvidia.com>
Signed-off-by: Andrea Righi <arighi@nvidia.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://patch.msgid.link/20260509180955.1840064-5-arighi@nvidia.com
On systems with asymmetric CPU capacity (e.g., ACPI/CPPC reporting
different per-core frequencies), the wakeup path uses
select_idle_capacity() and prioritizes idle CPUs with higher capacity
for better task placement. However, when those CPUs belong to SMT cores,
their effective capacity can be much lower than the nominal capacity
when the sibling thread is busy: SMT siblings compete for shared
resources, so a "high capacity" CPU that is idle but whose sibling is
busy does not deliver its full capacity. This effective capacity
reduction cannot be modeled by the static capacity value alone.
Introduce SMT awareness in the asym-capacity idle selection policy: when
SMT is active, always prefer fully-idle SMT cores over partially-idle
ones.
Prioritizing fully-idle SMT cores yields better task placement because
the effective capacity of partially-idle SMT cores is reduced; always
preferring them when available leads to more accurate capacity usage on
task wakeup.
On an SMT system with asymmetric CPU capacities (NVIDIA Vera Rubin),
SMT-aware idle selection has been shown to improve throughput by around
15-18% over NO_ASYM mainline and by around 60% over ASYM mainline, for
CPU-bound workloads (NVBLAS) running an amount of tasks equal to the
amount of SMT cores.
Reported-by: Felix Abecassis <fabecassis@nvidia.com>
Signed-off-by: Andrea Righi <arighi@nvidia.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Reviewed-by: K Prateek Nayak <kprateek.nayak@amd.com>
Link: https://patch.msgid.link/20260511142502.3873984-1-arighi@nvidia.com
On asymmetric CPU capacity systems, the wakeup path uses
select_idle_capacity(), which scans the span of sd_asym_cpucapacity
rather than sd_llc.
The has_idle_cores hint however lives on sd_llc->shared, so the
wakeup-time read of has_idle_cores operates on an LLC-scoped blob while
the actual scan/decision spans the asym domain; nr_busy_cpus also lives
in the same shared sched_domain data, but it's never used in the asym
CPU capacity scenario.
Therefore, move the sched_domain_shared object to sd_asym_cpucapacity
whenever the CPU has a SD_ASYM_CPUCAPACITY_FULL ancestor and that
ancestor is non-overlapping (i.e., not built from SD_NUMA). In that case
the scope of has_idle_cores matches the scope of the wakeup scan.
Fall back to attaching the shared object to sd_llc in three cases:
1) plain symmetric systems (no SD_ASYM_CPUCAPACITY_FULL anywhere);
2) CPUs in an exclusive cpuset that carves out a symmetric capacity
island: has_asym is system-wide but those CPUs have no
SD_ASYM_CPUCAPACITY_FULL ancestor in their hierarchy and follow
the symmetric LLC path in select_idle_sibling();
3) exotic topologies where SD_ASYM_CPUCAPACITY_FULL lands on an
SD_NUMA-built domain. init_sched_domain_shared() keys the shared
blob off cpumask_first(span), which on overlapping NUMA domains
would alias unrelated spans onto the same blob. Keep the shared
object on the LLC there; select_idle_capacity() gracefully skips
the has_idle_cores preference when sd->shared is NULL.
While at it, also rename the per-CPU sd_llc_shared to sd_balance_shared,
as it is no longer strictly tied to the LLC.
Co-developed-by: Andrea Righi <arighi@nvidia.com>
Signed-off-by: Andrea Righi <arighi@nvidia.com>
Signed-off-by: K Prateek Nayak <kprateek.nayak@amd.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Shrikanth Hegde <sshegde@linux.ibm.com>
Acked-by: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://patch.msgid.link/20260516055850.1345932-1-arighi@nvidia.com
nohz_balancer_kick() is reached from sched_balance_trigger(), which is
called from sched_tick(). sched_tick() runs with IRQs disabled, so the
additional rcu_read_lock/unlock() used around sched_domain accesses in
this path is redundant. Rely on the existing IRQ-disabled context (and
the rcu_dereference_all() checking) instead.
The same applies to set_cpu_sd_state_idle(), called from the idle entry
path with IRQs disabled, and to set_cpu_sd_state_busy(), reachable via
nohz_balance_exit_idle() from two contexts: nohz_balancer_kick() (IRQs
disabled, as above) and sched_cpu_deactivate() (the CPUHP_AP_ACTIVE
teardown, which runs under cpus_write_lock(), so it cannot race with
sched-domain rebuilds). In both cases the rcu_dereference_all()
validation is sufficient.
No functional change intended.
Suggested-by: K Prateek Nayak <kprateek.nayak@amd.com>
Signed-off-by: Andrea Righi <arighi@nvidia.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: K Prateek Nayak <kprateek.nayak@amd.com>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://patch.msgid.link/20260509180955.1840064-2-arighi@nvidia.com
There is a use of sched_smt_active() and explicit use of sched_smt_present.
Remove the explicit usage for better code maintenance and readability.
Note that this differs slightly for update_idle_core. It used to call
static_branch_unlikely earlier and now it will call static_branch_likely.
Signed-off-by: Shrikanth Hegde <sshegde@linux.ibm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Valentin Schneider <vschneid@redhat.com>
Link: https://patch.msgid.link/20260515172456.542799-5-sshegde@linux.ibm.com
For fastpaths such as wakeup and load balance even minimal code additions
can add up. is_core_idle is accessed during load balance.
Other callsites of is_core_idle make sched_smt_active() check first.
Make the same check in should_we_balance.
Rest of access to cpu_smt_mask isn't in fastpath.
Note: Remove the stale comment above is_core_idle. Enqueue methods
of fair aren't close to it anymore.
Suggested-by: K Prateek Nayak <kprateek.nayak@amd.com>
Signed-off-by: Shrikanth Hegde <sshegde@linux.ibm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Valentin Schneider <vschneid@redhat.com>
Link: https://patch.msgid.link/20260515172456.542799-4-sshegde@linux.ibm.com
Now, that cpu_smt_mask is defined as cpumask_of(cpu) for
CONFIG_SCHED_SMT=n, it is possible to get rid of the ifdeffery.
Effectively,
- This makes sched_smt_present is defined always
- cpumask_weight(cpumask_of(cpu)) == 1. So sched_smt_present_inc/dec
will never enable the sched_smt_present. Which is expected.
- Paths that were compile-time eliminated become runtime guarded
using static keys.
- Defines set_idle_cores, test_idle_cores, etc which could likely benefit
the CONFIG_SCHED_SMT=n systems to use the same optimizations within the
LLC at wakeups.
- This will expose sched_smt_present symbol for CONFIG_SCHED_SMT=n.
Likely not a concern.
- There is a bloat of code CONFIG_SCHED_SMT=n. (NR_CPUS=2048)
add/remove: 24/18 grow/shrink: 26/28 up/down: 6396/-3188 (3208)
Total: Before=30629880, After=30633088, chg +0.01%
- No code bloat for CONFIG_SCHED_SMT=y, which is expected.
- Add comments around stop_core_cpuslocked on why ifdefs are not
removed.
- This leaves the remaining uses of CONFIG_SCHED_SMT mainly for
topology building bits which has a policy based decision.
Signed-off-by: Shrikanth Hegde <sshegde@linux.ibm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Phil Auld <pauld@redhat.com>
Reviewed-by: Valentin Schneider <vschneid@redhat.com>
Acked-by: Tejun Heo <tj@kernel.org>
Tested-by: K Prateek Nayak <kprateek.nayak@amd.com>
Link: https://patch.msgid.link/20260515172456.542799-3-sshegde@linux.ibm.com
util_est_update() must be called after updating util_avg during the dequeue
of a task and only when the task is not delayed dequeue.
Move util_est_update() in update_load_avg().
Fixes: b55945c500 ("sched: Fix pick_next_task_fair() vs try_to_wake_up() race")
Closes: https://lore.kernel.org/all/20260512124653.305275-1-qyousef@layalina.io/
Reported-by: Qais Yousef <qyousef@layalina.io>
Reviewed-and-tested-by: Qais Yousef <qyousef@layalina.io>
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260518102345.268452-1-vincent.guittot@linaro.org
When CONFIG_HAVE_UNSTABLE_SCHED_CLOCK is disabled, sched_clock() is
already assumed to provide stable semantics, but the public header
doesn't provide a sched_clock_stable() stub for that case.
Add a header stub that always returns true and clean up the duplicate
local stub in ring_buffer.c, so callers can use sched_clock_stable()
unconditionally.
Signed-off-by: Yiyang Chen <cyyzero16@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Link: https://patch.msgid.link/56e45338858946cd9581b75c8bd45dd37dba52c5.1778773587.git.cyyzero16@gmail.com
Commit 77baa5bafc ("sched/cputime: Fix mul_u64_u64_div_u64() precision
for cputime") added a clamp in cputime_adjust():
if (unlikely(stime > rtime))
stime = rtime;
The justification was that mul_u64_u64_div_u64() could over-approximate
on some architectures (notably arm64 and the old 32-bit fallback), so
the mathematically impossible stime > rtime was nevertheless reachable
and would underflow utime = rtime - stime.
That premise no longer holds. Commit b29a62d87c ("mul_u64_u64_div_u64:
make it precise always") replaced the fallback implementation with an
exact 128-bit long division, and the x86_64 inline asm already produced
exact results. The helper now returns the mathematically correct
floor(a*b/d) on every architecture, so stime <= rtime is guaranteed by
stime <= stime + utime and the clamp is dead code.
Remove it along with its stale comment.
Signed-off-by: Nicolas Pitre <nico@fluxnic.net>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260514202629.673539-1-nico@fluxnic.net
Enqueue and replenish non-deferred deadline servers when their runtime is
exhausted and the replenishment timer could not be started because it is
too close to the wake-up instant.
Signed-off-by: Yuri Andriaccio <yurand2000@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260430213835.62217-2-yurand2000@gmail.com
Set the default total bandwidth for SCHED_DEADLINE tasks and servers
to ONE. FIFO/RR tasks are already throttled by fair-servers and
ext-servers, and the sysctl_sched_rt_runtime parameter now only
defines the total bw that is allowed to deadline entities.
Signed-off-by: Yuri Andriaccio <yurand2000@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260430213835.62217-22-yurand2000@gmail.com
The recent ptrace fix closed a hole where someone could rely on task->mm
becoming NULL during do_exit() to bypass dumpability checks. This api
here leans on on the very same check and so inherits the fix.
But there is no good reason to let it succeed at all once the target has
entered do_exit(). PF_EXITING is set by exit_signals() at the very top
of do_exit(), before exit_mm() and exit_files() run. Once we observe it,
the task is committed to dying and exit_files() will release the fdtable
shortly.
Fixes: 8649c322f7 ("pid: Implement pidfd_getfd syscall")
Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260518-obgleich-petersilie-2d77ccccf9b9@brauner
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
Because of the 8-byte alignment, the compiler will pad struct
bpf_common_attr to 24 bytes. That said, sizeof(attr_common) is 24 instead
of 20.
When check tail zero using sizeof(attr_common) in
bpf_check_uarg_tail_zero(), there will be 4 bytes that won't be checked.
To also check the padding 4 bytes, replace sizeof(attr_common) with
offsetofend(struct bpf_common_attr, log_true_size).
Fixes: f28771c069 ("bpf: Extend BPF syscall with common attributes support")
Signed-off-by: Leon Hwang <leon.hwang@linux.dev>
Link: https://lore.kernel.org/r/20260518145446.6794-2-leon.hwang@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
On fork without CLONE_VM, the child gets a new mm,
the parent's preferred_llc value is stale for the
child.
Fix this by resetting the task's preferred_llc to -1.
This bug was reported by sashiko.
Fixes: 47d8696b95 ("sched/cache: Assign preferred LLC ID to processes")
Signed-off-by: Chen Yu <yu.c.chen@intel.com>
Co-developed-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/0ec7309d0e24ede97656754d1505b7490403d966.1778703694.git.tim.c.chen@linux.intel.com
sched_cache_present is a global static key, but build_sched_domains()
is called per partition from the "Build new domains" loop in
partition_sched_domains_locked(). Each call unconditionally sets the
key based solely on the has_multi_llcs local variable for that partition.
The call to the last partition set the value even when there
are previous partitions with multiple LLCs.
If partition A (multi-LLC) is built first, the key is enabled. Then
when partition B (single-LLC) is built, the key is disabled. The
multi-LLC partition A is still active but the key is now off.
Fix it by doing a similar thing as sched_energy_present: check the
multi-LLCs during the iteration over all the partitions rather than
checking it on a single partition.
This bug was reported by sashiko.
Fixes: d59f4fd1d3 ("sched/cache: Enable cache aware scheduling for multi LLCs NUMA node")
Signed-off-by: Chen Yu <yu.c.chen@intel.com>
Co-developed-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/c541af2547d54509fbfd3b3a1e8072e2e5c7ff68.1778703694.git.tim.c.chen@linux.intel.com
If there are multiple LLCs in the system, cache aware scheduling
should be enabled. However, there is a corner case where, if there
is a single NUMA node and a single LLC per node, cache aware
scheduling will be turned on in the current implementation -
because at this moment, the parent domain has not yet been
degenerated, and it is possible that the current domain has the
same cpu span as its parent. There is no need to turn cache aware
scheduling on in this scenario.
Fix it by iterating the parent domains to find a domain that is
a superset of the current sd_llc, so that later, after the duplicated
parent domains have been degenerated, cache aware scheduling will
take effect.
For example, the expected behavior would be:
2 sockets, 1 LLC per socket: MC span=0-3, PKG span=0-7, has_multi_llcs=true
1 socket, 2 LLCs per socket: MC span=0-3, PKG span=0-7, has_multi_llcs=true
2 sockets, 2 LLCs per socket: MC span=0-3, PKG span=0-7, has_multi_llcs=true
1 socket, 1 LLC per socket: MC span=0-3, PKG span=0-3, has_multi_llcs=false
This bug was reported by sashiko.
Fixes: d59f4fd1d3 ("sched/cache: Enable cache aware scheduling for multi LLCs NUMA node")
Signed-off-by: Chen Yu <yu.c.chen@intel.com>
Co-developed-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/6328a8a7f40925cec2a712d81ee58128a4c4444a.1778703694.git.tim.c.chen@linux.intel.com
sched_cache_active_set_unlocked() checks hardware support without
locks:
static void sched_cache_active_set(bool locked)
{
/* hardware does not support */
if (!static_branch_likely(&sched_cache_present)) {
_sched_cache_active_set(false, locked);
return;
}
...
If build_sched_domains() runs concurrently during CPU hotplug,
it can disable sched_cache_present under sched_domains_mutex
and the CPU hotplug lock. If a debugfs write thread evaluates
sched_cache_present as true right before that, and then blocks
or gets preempted, it might proceed to enable sched_cache_active
after the hardware support has been marked as absent. Make it
safer by acquiring cpus_read_lock() and sched_domains_mutex_lock()
when the user changes sched_cache_active via debugfs.
This bug was reported by sashiko.
Fixes: 067a313581 ("sched/cache: Allow the user space to turn on and off cache aware scheduling")
Signed-off-by: Chen Yu <yu.c.chen@intel.com>
Co-developed-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/9afddf439687f04bb56b46625bd9f153eb8abad5.1778703694.git.tim.c.chen@linux.intel.com
The currently running task cur may not be a CFS task, such as
an RT or Deadline task. For non-CFS tasks, the task_util(cur)
utilization average is not maintained, so this might pass a
stale or meaningless value to can_migrate_llc().
Check if the task is CFS before getting its task_util().
This bug was reported by sashiko.
Fixes: 714059f79f ("sched/cache: Handle moving single tasks to/from their preferred LLC")
Signed-off-by: Chen Yu <yu.c.chen@intel.com>
Co-developed-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/f9161133cf040d286dca11344a112c5ef2a5253d.1778703694.git.tim.c.chen@linux.intel.com
There is a race condition that, after a task is enqueued
on a runqueue, task_llc(p) may change due to CPU hotplug,
because the llc_id is dynamically allocated and adjusted
at runtime.
Therefore, checking task_llc(p) to determine whether the
task is being dequeued from its preferred LLC is unreliable
and can cause inconsistent values.
To fix this problem, record whether p is enqueued on its
preferred LLC, in order to pair with account_llc_dequeue()
to maintain a consistent nr_pref_llc_running per runqueue.
This bug was reported by sashiko, and the solution was once
suggested by Prateek.
Fixes: 46afe3af7e ("sched/cache: Track LLC-preferred tasks per runqueue")
Suggested-by: K Prateek Nayak <kprateek.nayak@amd.com>
Signed-off-by: Chen Yu <yu.c.chen@intel.com>
Co-developed-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/0c8c6a1571d66792a4d2ff0103ba3cc13e059046.1778703694.git.tim.c.chen@linux.intel.com
mm->sc_stat.cpu is written by task_cache_work() and could be read
locklessly by several functions on other CPUs. Use READ_ONCE and
WRITE_ONCE on mm->sc_stat.cpu access and write to prevent inconsistent
values from compiler optimizations when there are multiple accesses.
For example in get_pref_llc(), if the writer updated the field between
two compiler-generated loads, the validation (e.g., cpu != -1) and
subsequent use (e.g., llc_id(cpu)) could operate on different values,
allowing a negative CPU ID to be used as an index.
Leave plain write in mm_init_sched(), where the mm is not
yet visible to other CPUs.
This bug was reported by sashiko.
Fixes: 47d8696b95 ("sched/cache: Assign preferred LLC ID to processes")
Signed-off-by: Chen Yu <yu.c.chen@intel.com>
Co-developed-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/63ea494f12efcf265d7134400a06cd75d7f2c310.1778703694.git.tim.c.chen@linux.intel.com
A concurrent task exit might cause a NULL pointer dereference
in account_mm_sched(). Use the locally cached mm pointer instead,
since the active_mm reference guarantees the structure remains
allocated. Meanwhile, skip the kernel thread because it has
nothing to do with cache aware scheduling.
This bug was reported by sashiko and Vern.
Fixes: df0d984759 ("sched/cache: Introduce infrastructure for cache-aware load balancing")
Reported-by: Vern Hao <haoxing990@gmail.com>
Signed-off-by: Chen Yu <yu.c.chen@intel.com>
Co-developed-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/all/09cf7ee3-6e27-4505-9692-4b4a4707c8b2@gmail.com/
Link: https://patch.msgid.link/066d8cfa45d4822bf4367e788c50377c66bbcc82.1778703694.git.tim.c.chen@linux.intel.com
rcu_dereference_all() should be used to access the
sd_llc domain under RCU protection.
This bug was reported by sashiko.
Fixes: df0d984759 ("sched/cache: Introduce infrastructure for cache-aware load balancing")
Signed-off-by: Chen Yu <yu.c.chen@intel.com>
Co-developed-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/2dc49455e861215d8059a1c877953f0b95990038.1778703694.git.tim.c.chen@linux.intel.com
Introduce a set of debugfs knobs to control how aggressively the
cache aware scheduling does the task aggregation.
(1) aggr_tolerance
With sched_cache enabled, the scheduler uses a process's footprint
as a proxy for its LLC footprint to determine if aggregating tasks
on the preferred LLC could cause cache contention. If the footprint
exceeds the LLC size, aggregation is skipped. Since the kernel
cannot efficiently track per-task cache usage (resctrl is
user-space only), userspace can provide a more accurate hint.
Introduce /sys/kernel/debug/sched/llc_balancing/aggr_tolerance to
let users control how strictly footprint limits aggregation. Values
range from 0 to 100:
- 0: Cache-aware scheduling is disabled.
- 1: Strict; tasks with footprint larger than LLC size are skipped.
- >=100: Aggressive; tasks are aggregated regardless of footprint.
For example, with a 32MB L3 cache:
- aggr_tolerance=1 -> tasks with footprint > 32MB are skipped.
- aggr_tolerance=99 -> tasks with footprint > 784GB are skipped
(784GB = (1 + (99 - 1) * 256) * 32MB).
Similarly, /sys/kernel/debug/sched/llc_balancing/aggr_tolerance also
controls how strictly the number of active threads is considered when
doing cache aware load balance. The number of SMTs is also considered.
High SMT counts reduce the aggregation capacity, preventing excessive
task aggregation on SMT-heavy systems like Power10/Power11.
Yangyu suggested introducing separate aggregation controls for the
number of active threads and memory footprint checks. Since there are
plans to add per-process/task group controls, fine-grained tunables are
deferred to that implementation.
(2) epoch_period, epoch_affinity_timeout,
imb_pct, overaggr_pct are also turned into tunables.
Suggested-by: K Prateek Nayak <kprateek.nayak@amd.com>
Suggested-by: Madadi Vineeth Reddy <vineethr@linux.ibm.com>
Suggested-by: Shrikanth Hegde <sshegde@linux.ibm.com>
Suggested-by: Tingyin Duan <tingyin.duan@gmail.com>
Suggested-by: Jianyong Wu <jianyong.wu@outlook.com>
Suggested-by: Yangyu Chen <cyy@cyyself.name>
Signed-off-by: Chen Yu <yu.c.chen@intel.com>
Co-developed-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Tingyin Duan <tingyin.duan@gmail.com>
Link: https://patch.msgid.link/1c62cc060ba2b33d7b1f0ed98b3390128edbae93.1778703694.git.tim.c.chen@linux.intel.com
Prateek and Tingyin reported that memory-intensive workloads (such as
stream) can saturate memory bandwidth and caches on the preferred LLC
when sched_cache aggregates too many threads.
To mitigate this, estimate a process's memory footprint by comparing
its NUMA balancing fault statistics to the size of the LLC. If the
footprint exceeds the LLC size, skip cache-aware scheduling.
Note that footprint is only an approximation of the memory footprint,
since the kernel lacks suitable metrics to estimate the real working
set. If a user-provided hint is available in the future, it would be
more accurate. A later patch will allow users to provide a hint to
adjust this threshold.
Suggested-by: K Prateek Nayak <kprateek.nayak@amd.com>
Suggested-by: Vern Hao <vernhao@tencent.com>
Signed-off-by: Chen Yu <yu.c.chen@intel.com>
Co-developed-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Tingyin Duan <tingyin.duan@gmail.com>
Link: https://patch.msgid.link/95cf64a385bcc12f18dcebe9d59e8d3ba8bb318f.1778703694.git.tim.c.chen@linux.intel.com
Cache aware scheduling needs to know the LLC size that a process
can use, so as to avoid memory-intensive tasks from being
over-aggregated on a single LLC.
Introduce a preparation patch to add get_effective_llc_bytes() to
get the LLC size that a CPU can use. The function can be further
enhanced by subtracting the LLC cache ways reserved by resctrl
(CAT in Intel RDT, etc).
Suggested-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Chen Yu <yu.c.chen@intel.com>
Co-developed-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Tingyin Duan <tingyin.duan@gmail.com>
Link: https://patch.msgid.link/37afee09ff608034da0ce149e72d33b6f4698edf.1778703694.git.tim.c.chen@linux.intel.com
For a single thread, the current wakeup path tends to place it
on the same LLC where it was previously running with cache-hot
data. There is no need to enable cache-aware scheduling for
single-threaded processes for the following reasons:
1. Cache-aware scheduling primarily benefits multi-threaded
processes where threads share data. Single-threaded processes
typically have no inter-thread data sharing and thus gain little.
2. Enabling it incurs the additional overhead of tracking the
thread's residency in the LLCs.
3. Bypassing single-threaded processes avoids excessive
concentration of such tasks on a single LLC.
Nevertheless, this check can be omitted if users explicitly
provide hints for such single-threaded workloads where different
processes have shared memory, e.g., via prctl() or other interfaces
to be added in the future.
Signed-off-by: Chen Yu <yu.c.chen@intel.com>
Co-developed-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Tingyin Duan <tingyin.duan@gmail.com>
Link: https://patch.msgid.link/8a59a13aa58fdb48e410ecb2aabd97fe3ea5d256.1778703694.git.tim.c.chen@linux.intel.com
A performance regression was observed by Prateek when running hackbench
with many threads per process (high fd count). To avoid this, processes
with a large number of active threads are excluded from cache-aware
scheduling.
With sched_cache enabled, record the number of active threads in each
process during the periodic task_cache_work(). While iterating over
CPUs, if the currently running task belongs to the same process as the
task that launched task_cache_work(), increment the active thread count.
If the number of active threads within the process exceeds the number
of Cores (divided by the SMT number) in the LLC, do not enable
cache-aware scheduling. However, on systems with a smaller number of
CPUs within 1 LLC, like Power10/Power11 with SMT4 and an LLC size of 4,
this check effectively disables cache-aware scheduling for any process.
One possible solution suggested by Peter is to use an LLC-mask instead
of a single LLC value for preference. Once there are a 'few' LLCs as
preference, this constraint becomes a little easier. It could be an
enhancement in the future.
For users who wish to perform task aggregation regardless, a debugfs knob
is provided for tuning in a subsequent change.
Suggested-by: K Prateek Nayak <kprateek.nayak@amd.com>
Suggested-by: Aaron Lu <ziqianlu@bytedance.com>
Signed-off-by: Chen Yu <yu.c.chen@intel.com>
Co-developed-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Tingyin Duan <tingyin.duan@gmail.com>
Link: https://patch.msgid.link/d076cd21a8e6c6341d1e2d927e118db770ebb650.1778703694.git.tim.c.chen@linux.intel.com
Scanning online CPUs to calculate the occupancy might be
time-consuming. Only allow 1 thread of the process to scan
the CPUs at the same time, which is similar to what
NUMA balance does in task_numa_work().
Signed-off-by: Jianyong Wu <wujianyong@hygon.cn>
Signed-off-by: Chen Yu <yu.c.chen@intel.com>
Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/5672b52e588b855b01e5a1a17822f7c6c7237a3d.1778703694.git.tim.c.chen@linux.intel.com
css_rstat_updated() is exposed as a BPF kfunc and accepts a
caller-provided cpu argument. The function uses cpu for per-cpu rstat
lookups without checking whether it refers to a valid possible CPU.
A BPF iter/cgroup program with CAP_BPF and CAP_PERFMON can pass an
invalid cpu value. On an unfixed UBSCAN_BOUNDS test kernel, cpu ==
0x7fffffff triggers:
UBSAN: array-index-out-of-bounds in kernel/cgroup/rstat.c:31:9
index 2147483647 is out of range for type 'long unsigned int [64]'
Call Trace:
css_rstat_updated
bpf_iter_run_prog
cgroup_iter_seq_show
bpf_seq_read
Add cpu validation to the BPF-facing css_rstat_updated() kfunc and
move the common implementation to __css_rstat_updated() for in-kernel
callers.
Fixes: a319185be9 ("cgroup: bpf: enable bpf programs to integrate with rstat")
Signed-off-by: Qing Ming <a0yami@mailbox.org>
Signed-off-by: Tejun Heo <tj@kernel.org>
While an srcu_struct structure is in the midst of switching from CPU-0
to all-CPUs state, it can attempt to invoke callbacks for CPUs that
have never been online. Worse yet, it can attempt in invoke callbacks
for CPUs that never will be online, even including imaginary CPUs not in
cpu_possible_mask. This can cause hangs on s390, which is not set up to
deal with workqueue handlers being scheduled on such CPUs. This commit
therefore causes Tree SRCU to refrain from queueing workqueue handlers
on CPUs that have not yet (and might never) come online.
Because callbacks are not invoked on CPUs that have not been
online, it is an error to invoke call_srcu(), synchronize_srcu(), or
synchronize_srcu_expedited() on a CPU that is not yet fully online.
However, it turns out to be less code to redirect the callbacks
from too-early invocations of call_srcu() than to warn about such
invocations. This commit therefore also redirects callbacks queued on
not-yet-fully-online CPUs to the boot CPU.
Reported-by: Vasily Gorbik <gor@linux.ibm.com>
Fixes: 61bbcfb505 ("srcu: Push srcu_node allocation to GP when non-preemptible")
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Tested-by: Vasily Gorbik <gor@linux.ibm.com>
Tested-by: Samir <samir@linux.ibm.com>
Reviewed-by: Shrikanth Hegde <sshegde@linux.ibm.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Signed-off-by: Boqun Feng <boqun@kernel.org>
All accesses to the event counters are serialized by rdmacg_mutex,
making the READ_ONCE() annotations unnecessary. Remove them.
Signed-off-by: Tao Cui <cuitao@kylinos.cn>
Signed-off-by: Tejun Heo <tj@kernel.org>
Introduce device-managed helpers for clocksource registration.
The clocksource framework currently provides __clocksource_register_scale()
along with convenience wrappers for Hz and kHz registration. However,
drivers must handle error paths and cleanup manually, typically by pairing
registration with an explicit clocksource_unregister() call.
Add a devm-based variant, __devm_clocksource_register_scale(), along with
devm_clocksource_register_hz() and devm_clocksource_register_khz() helpers.
These helpers register the clocksource and attach a devres action to
automatically unregister it on driver detach or probe failure.
This simplifies driver code by:
* removing explicit cleanup paths
* ensuring correct teardown ordering
* aligning with the devm-based resource management model widely used
across the kernel
While drivers can open-code devm_add_action_or_reset(), providing a
dedicated helper avoids duplication, reduces boilerplate, and ensures
consistent usage across drivers, following patterns used in other
subsystems.
This is also particularly useful for drivers built as modules, where
device-managed resource handling avoids manual cleanup in remove paths and
ensures correct teardown on module unload.
This helper is self-contained and can be adopted progressively by drivers.
No functional change.
Signed-off-by: Daniel Lezcano <daniel.lezcano@oss.qualcomm.com>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Link: https://patch.msgid.link/20260506153831.605159-1-daniel.lezcano@oss.qualcomm.com
dma_map_resource() uses pfn_valid() to ensure the range is not RAM.
However, pfn_valid() only checks for availability of the memory map for
a PFN but it does not ensure that the PFN is actually backed by RAM. On
ARM64 with SPARSEMEM (128MB section granularity), MMIO addresses that
share a section with RAM will falsely trigger the WARN_ON_ONCE and cause
dma_map_resource() to return DMA_MAPPING_ERROR.
This causes a WARNING on Raspberry Pi 4 during spi_bcm2835 probe because
the SPI FIFO register (0xfe204004) falls in the same sparsemem section
as the end of RAM (0xf8000000-0xfbffffff), both in section 31
(0xf8000000-0xffffffff).
Move the sanity check from dma_map_resource() into debug_dma_map_phys()
and replace the unreliable pfn_valid() with pfn_valid() &&
!PageReserved(), which correctly identifies actual usable RAM without
false positives for MMIO regions that happen to have struct pages.
Since dma_map_resource() is dma_map_phys(DMA_ATTR_MMIO), the check
applies equally to both APIs. Any non-reserved page represents kernel
memory to a sufficient degree that using DMA_ATTR_MMIO on it is almost
certainly wrong and risks breaking coherency on non-coherent platforms.
ZONE_DEVICE pages used for PCI P2P DMA (MEMORY_DEVICE_PCI_P2PDMA) have
PageReserved set, so they will not trigger a false positive.
The check no longer blocks the mapping and uses err_printk() to
integrate with dma-debug filtering.
Fixes: f7326196a7 ("dma-mapping: export new dma_*map_phys() interface")
Reviewed-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Jianpeng Chang <jianpeng.chang.cn@windriver.com>
Reviewed-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Link: https://lore.kernel.org/r/20260513072209.1486986-1-jianpeng.chang.cn@windriver.com
When a main program with exception_boundary has outgoing stack
arguments (e.g. from calling subprogs with >5 args), bpf_throw() fails
to correctly restore callee-saved registers, causing a kernel crash.
The x86 JIT allocates the outgoing stack arg area below the
callee-saved registers via 'sub rsp, outgoing_rsp' in the prologue.
When bpf_throw() unwinds, it captures the main program's sp (which
includes this outgoing area) and passes it to the exception callback.
The callback gets rsp and rbp, followed by pop_callee_regs, but rsp
points into the outgoing arg area rather than the callee-saved
registers, so the pops restore garbage values. Returning to the
kernel with corrupted callee-saved registers causes a crash.
Fix this by adjusting the sp (adding stack_arg_sp_adjust) passed to
the exception callback, so it points to the bottom of the callee-saved
registers instead of the outgoing arg area. When stack_arg_sp_adjust
is 0 (the common case), this is a no-op.
Fixes: 324c3ca6ee ("bpf,x86: Implement JIT support for stack arguments")
Acked-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20260517150702.288031-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Pull to receive:
39e25a2100 ("sched_ext: Drop NONE early return in scx_disable_and_exit_task()")
b273b75b8d ("sched_ext: INIT_LIST_HEAD() &sch->all in scx_alloc_and_add_sched()")
cceb874eee ("sched_ext: Defer sub_kset base put to scx_sched_free_rcu_work")
6ae315d379 ("sched_ext: Use HK_TYPE_DOMAIN_BOOT to detect isolcpus= domain isolation")
515e3996a4 ("sched_ext: Fix deadlock between scx_root_disable() and concurrent forks")
to prepare for-7.2 for further sub-sched changes.
Signed-off-by: Tejun Heo <tj@kernel.org>
scx_root_disable() enters SCX_DISABLING before it grabs scx_enable_mutex to
clear __scx_switched_all and scx_switching_all. task_should_scx() short-circuits on DISABLING,
so forks in that window land on fair while next_active_class() still skips
fair - the new tasks stall.
This can deadlock the disable path itself: scx_alloc_and_add_sched() runs
under scx_enable_mutex and creates a helper kthread; if that new kthread is
one of the stalled fair tasks, the mutex holder waits forever and
scx_root_disable() can never make progress. Only sub-sched support exposes
this, since sub-sched enables are the only path where
scx_alloc_and_add_sched() can race the root's disable.
Move the DISABLING check after @scx_switching_all. @scx_switching_all
serves as a proxy for __scx_switched_all, so while it's set, forks keep
going to scx. Once cleared, DISABLING applies normally.
v2: Reword in-source comment and description. (Andrea)
Fixes: 337ec00b1d ("sched_ext: Implement cgroup sub-sched enabling and disabling")
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Andrea Righi <arighi@nvidia.com>
- Add more functions to the remote allowed list
randconfig found more functions that are allowed for the remote code for
s390 and arm. Add them to the allowed list.
- Fix remote_test error path
If one of the simple ring buffers fails to load, the code is supposed to
rollback its initialized buffers. Instead of rolling back the buffers for
the failed load, it uses the global variable and rolls back all the
successfully loaded buffers.
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Merge tag 'trace-v7.1-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace
Pull tracing fixes from Steven Rostedt:
- Add more functions to the remote allowed list
randconfig found more functions that are allowed for the remote code
for s390 and arm. Add them to the allowed list.
- Fix remote_test error path
If one of the simple ring buffers fails to load, the code is supposed
to rollback its initialized buffers. Instead of rolling back the
buffers for the failed load, it uses the global variable and rolls
back all the successfully loaded buffers.
* tag 'trace-v7.1-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
tracing: Fix desc in error path for the trace remote test module
ring-buffer remote: Avoid unexpected symbol warnings (arm, s390)
Global subprogs are verified independently and are not descended into
when their callers are symbolically executed. This means a caller can
hold references or locks across a global subprog call that may throw,
while the verifier only checks the non-exceptional return path at the
call site.
Record whether a subprog might throw in the CFG summary pass, alongside
the existing might_sleep and packet-data-changing summaries, and
propagate that effect through reachable callees.
When a global subprog is marked as possibly throwing, push the normal
continuation and validate the exceptional path immediately at the call
site, avoiding a synthetic exception state and associated special case
in the pruning checks.
Fixes: f18b03faba ("bpf: Implement BPF exceptions")
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20260517075530.3461166-2-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
- Fix use-after-free in irq_work_single() on PREEMPT_RT
(Jiayuan Chen)
- Don't call add_interrupt_randomness() for NMIs
in handle_percpu_devid_irq() (Mark Rutland)
- Remove unused function in the ath79-cpu irqchip driver
causing LKP CI build warnings (Rosen Penev)
- Fix IRQ allocation/teardown leakage regressions in the GICv5
irqchip driver (Sascha Bischoff)
- Fix an IRQ trigger type regression in the Meson S4 SoC irqchip
driver (Xianwei Zhao)
- Fix CPU offlining regression in the RiscV IMSIC irqchip driver
(Yong-Xuan Wang)
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'irq-urgent-2026-05-17' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull IRQ fixes from Ingo Molnar:
- Fix use-after-free in irq_work_single() on PREEMPT_RT (Jiayuan Chen)
- Don't call add_interrupt_randomness() for NMIs in
handle_percpu_devid_irq() (Mark Rutland)
- Remove unused function in the ath79-cpu irqchip driver causing LKP
CI build warnings (Rosen Penev)
- Fix IRQ allocation/teardown leakage regressions in the GICv5 irqchip
driver (Sascha Bischoff)
- Fix an IRQ trigger type regression in the Meson S4 SoC irqchip driver
(Xianwei Zhao)
- Fix CPU offlining regression in the RiscV IMSIC irqchip driver
(Yong-Xuan Wang)
* tag 'irq-urgent-2026-05-17' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
irq_work: Fix use-after-free in irq_work_single() on PREEMPT_RT
irqchip/riscv-imsic: Clear interrupt move state during CPU offlining
irqchip/meson-gpio: Use the correct register in meson_s4_gpio_irq_set_type()
irqchip/ath79-cpu: Remove unused function
genirq/chip: Don't call add_interrupt_randomness() for NMIs
irqchip/gic-v5: Allocate ITS parent LPIs as a range
irqchip/gic-v5: Support range allocation for LPIs
irqchip/gic-v5: Move LPI allocation into the LPI domain
Remove a redundant stack_arg_cnt check in __bpf_prog_select_runtime()
and start the stack arg loop from index 0 in bpf_fixup_call_args().
Both changes are no-ops that simplify the code:
In __bpf_prog_select_runtime(), the subprog_info[0].stack_arg_cnt
check is unreachable:
- when there is only a main program (no bpf-to-bpf calls),
subprog_info[0].stack_arg_cnt is always 0 because the main
program's arg_cnt is forced to 1
- when bpf-to-bpf calls use stack args and JIT succeeds,
fp->bpf_func is set and this code is skipped
- when JIT fails, bpf_fixup_call_args() rejects the program
before we get to __bpf_prog_select_runtime().
In bpf_fixup_call_args(), starting the loop at i=1 skipped subprog 0,
which is safe since the main program always has arg_cnt=1 and thus
bpf_in_stack_arg_cnt() returns 0. Starting at i=0 removes the need
to reason about this invariant.
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20260515225101.824054-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
arg_track_join() logs state transitions at CFG merge points. For
stack arg slots (r >= MAX_BPF_REG), it printed "r11:", "r12:", etc.,
which is misleading since r11 is a special register (BPF_REG_PARAMS)
not meaningful to the user.
Fix it to print "sa0:", "sa1:", etc., matching the per-instruction
transition log in arg_track_log() which already uses the "sa" prefix.
Update the existing stack_arg_pruning_type_mismatch selftest to expect
the corrected format.
Fixes: 2af4e79277 ("bpf: Extend liveness analysis to track stack argument slots")
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20260515225056.823086-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
btf_prepare_func_args() sets sub->arg_cnt before validating arg types.
If validation fails (e.g. unsupported pointer type in a static subprog),
check_outgoing_stack_args() is skipped because btf_check_func_arg_match()
returns early. For static subprogs, check_func_call() ignores non-EFAULT
errors and proceeds with the call.
This causes the callee to read stack arg slots that the caller never
stored or not initialized, potentially dereferencing NULL caller->stack_arg_regs
or getting no-initialized value.
To fix the issue, when btf_prepare_func_args() fails and the subprog expects
stack args, call check_outgoing_stack_args() to verify the caller initialized
the slots. Return -EFAULT on failure so the error is not ignored.
Fixes: 3ab5bd317e ("bpf: Set sub->arg_cnt earlier in btf_prepare_func_args()")
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20260515225040.821515-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
During initialisation in remote_test_load(), if one of the
simple_ring_buffer fails to initialise, the error path attempts to
rollback initialised buffers. However, the rollback incorrectly uses the
global pointer to the trace descriptor, which is only set upon
successful load completion. Fix the error path by using the local
pointer to the descriptor.
Link: https://patch.msgid.link/20260515201616.337469-1-vdonnefort@google.com
Fixes: ea908a2b79 ("tracing: Add a trace remote module for testing")
Reported-by: Sashiko <sashiko-bot@kernel.org>
Signed-off-by: Vincent Donnefort <vdonnefort@google.com>
base-commit: 5d6919055d
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
The now more verbose check found more architecture specific symbol
missing from the whitelist, during randconfig testing on s390
and 32-bit arm:
Unexpected symbols in kernel/trace/simple_ring_buffer.o:
U __aeabi_unwind_cpp_pr1
Unexpected symbols in kernel/trace/simple_ring_buffer.o:
U __s390_indirect_jump_r1
U __s390_indirect_jump_r10
U __s390_indirect_jump_r14
U __s390_indirect_jump_r2
U __s390_indirect_jump_r5
U __s390_indirect_jump_r7
U __s390_indirect_jump_r8
U __s390_indirect_jump_r9
make[6]: *** [/home/arnd/arm-soc/kernel/trace/Makefile:160: kernel/trace/simple_ring_buffer.o.checked] Error 1
Add these to the list and keep it roughly sorted into sanitizer
and architecture symbols.
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Vincent Donnefort <vdonnefort@google.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Link: https://patch.msgid.link/20260515105717.1023007-1-arnd@kernel.org
Fixes: 1211907ac0 ("tracing: Generate undef symbols allowlist for simple_ring_buffer")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Same race shape as the rmdir path that 93618edf75 ("cgroup: Defer css
percpu_ref kill on rmdir until cgroup is depopulated") fixed: a task past
exit_signals() whose cset subsys[ssid] still pins the disabled controller's
css can be touching subsys state while ->css_offline() runs. The earlier
patches in this series built up the per-subsys-css deferral machinery and
routed cgroup_destroy_locked() through it. Apply the same shape to
cgroup_apply_control_disable():
kill_css_sync(css);
if (!css_is_populated(css))
kill_css_finish(css);
When the dying css is still populated, kill_css_finish() is deferred. The
walker in css_update_populated() fires kill_finish_work once the css's
hierarchical populated count drops to zero.
cgroup_lock_and_drain_offline()'s wait predicate switches from
percpu_ref_is_dying() to css_is_dying(). CSS_DYING is set by kill_css_sync()
and is a strict superset of percpu_ref_is_dying. Without this change, a +cpu
re-enable after a deferred -cpu disable would skip the drain (percpu_ref
isn't killed yet) and observe the still-CSS_DYING css through cgroup_css(),
treating it as live.
Signed-off-by: Tejun Heo <tj@kernel.org>
93618edf75 ("cgroup: Defer css percpu_ref kill on rmdir until cgroup is
depopulated") deferred kill_css_finish() at the cgroup level: rmdir waits
for the entire cgroup's populated count to drop to zero, then fires
kill_css_finish() on every subsystem css at once. Replace that with
per-subsys-css deferral. Each subsystem css now tracks its own hierarchical
populated count and independently defers its kill_css_finish() until its own
subtree drains.
The rmdir-race fix carries through unchanged in shape. The dying css's
->css_offline() still waits until no PF_EXITING task references it, and v2's
cgroup-level machinery goes away.
cgroup_apply_control_disable() has the same race shape (PF_EXITING tasks
pinning a css whose ->css_offline() is about to run) and stays synchronous
here. This patch lays the groundwork for fixing it - per-cgroup waiting
can't gate one subsys css being killed while the rest of the cgroup stays
live, but per-css can.
Subtree-wide invariant preserved: a dying ancestor css stays populated
through nr_populated_children until every dying descendant's task drains, so
the walker fires the ancestor's kill_finish_work only after all descendants
have drained.
Add paired smp_mb()s in kill_css_sync() and css_update_populated() to fence
the StoreLoad on (CSS_DYING, populated counter), guaranteeing that either
the walker queues kill_finish_work or the caller fires synchronously.
cgroup_destroy_locked() was implicitly fenced by an unrelated css_set_lock
pair; cgroup_apply_control_disable() in the next patch is not.
Signed-off-by: Tejun Heo <tj@kernel.org>
Later patches replace the cgroup-level finish_destroy_work deferral added
by 93618edf75 ("cgroup: Defer css percpu_ref kill on rmdir until cgroup
is depopulated") with a per-subsys-css deferral. That needs each subsystem
css to track its own populated count. Move the populated counters from
cgroup onto cgroup_subsys_state. cgroup->self is itself a
cgroup_subsys_state and self.parent walks the same chain as cgroup_parent(),
so cgroup_update_populated() generalizes to a single css_update_populated()
taking a css. The cgroup-side bookkeeping runs only when the walk started
from a self css.
Keep nr_populated_{domain,threaded}_children on cgroup. Both sum to
self.nr_populated_children, but staying as dedicated fields to allow readers
like cgroup_can_be_thread_root() unlocked access.
css_set_update_populated() also walks the per-subsys-css chain so each
subsystem css's hierarchical populated count is maintained. No reader
consumes those counts yet.
Signed-off-by: Tejun Heo <tj@kernel.org>
cgroup_update_populated() updates nr_populated_csets,
nr_populated_domain_children, and nr_populated_threaded_children under
css_set_lock, but cgroup_has_tasks(), cgroup_is_populated(), and
cgroup_can_be_thread_root() read them without holding it. Use
READ_ONCE/WRITE_ONCE.
Signed-off-by: Tejun Heo <tj@kernel.org>
cpuset reads cs->css.cgroup->nr_populated_csets directly in two places to
test whether a cgroup has tasks. cgroup.c already has a matching helper,
cgroup_has_tasks(). Move it to cgroup.h as static inline and use that
instead. This is to prepare for relocation of cgroup->nr_populated_csets. No
semantic change.
Signed-off-by: Tejun Heo <tj@kernel.org>
Building without CONFIG_BPF_EVENTS produces a build-time
warning:
WARN: resolve_btfids: unresolved symbol bpf_session_is_return
The function is actually defined in kernel/trace/bpf_trace.o,
which is built conditionally based on configuration.
Make the reference to this function conditional as well,
as is already done in the bpf verifier for other functions.
Fixes: 8fe4dc4f64 ("bpf: change prototype of bpf_session_{cookie,is_return}")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Link: https://lore.kernel.org/r/20260515113242.2706303-1-arnd@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Add per-cgroup local event counters to track RDMA resource limit
exhaustion from the perspective of individual cgroups. The
rdma.events.local file reports two per-resource counters:
- max: number of times this cgroup's limit was the one that blocked
an allocation in the subtree
- alloc_fail: number of allocation attempts originating from this
cgroup that failed due to an ancestor's limit
This mirrors the design of pids.events.local, where events are
attributed to the cgroup that imposed the limit, not necessarily the
cgroup where the allocation was attempted.
Also extend rdma.events with a hierarchical alloc_fail counter that
tracks allocation failures propagating upward from the requesting
cgroup, complementing the existing max counter, so that rdma.events
and rdma.events.local share the same output format.
Signed-off-by: Tao Cui <cuitao@kylinos.cn>
Signed-off-by: Tejun Heo <tj@kernel.org>
Add per-device hierarchical event counters to track when RDMA resource
limits are exceeded. The rdma.events file reports max event counts
propagated upward from the cgroup whose limit was hit to all ancestors.
This mirrors the design of pids.events, where events are attributed to
the cgroup that imposed the limit, not necessarily the cgroup where the
allocation was attempted. Userspace can monitor this file via
poll/epoll for real-time notification of resource exhaustion.
Signed-off-by: Tao Cui <cuitao@kylinos.cn>
Signed-off-by: Tejun Heo <tj@kernel.org>
rdma.peak tracks the high watermark of resource usage per device,
giving a better baseline on which to set rdma.max. Polling
rdma.current isn't feasible since it would miss short-lived spikes.
This interface is analogous to memory.peak.
Signed-off-by: Tao Cui <cuitao@kylinos.cn>
Signed-off-by: Tejun Heo <tj@kernel.org>
Some unit tests intentionally trigger warning backtraces by passing bad
parameters to kernel API functions. Such unit tests typically check the
return value from such calls, not the existence of the warning backtrace.
Such intentionally generated warning backtraces are neither desirable
nor useful for a number of reasons:
- They can result in overlooked real problems.
- A warning that suddenly starts to show up in unit tests needs to be
investigated and has to be marked to be ignored, for example by
adjusting filter scripts. Such filters are ad hoc because there is
no real standard format for warnings. On top of that, such filter
scripts would require constant maintenance.
Solve the problem by providing a means to suppress warning backtraces
originating from the current kthread while executing test code. Since
each KUnit test runs in its own kthread, this effectively scopes
suppression to the test that enabled it. Limit changes to generic code
to the absolute minimum.
Implementation details:
Suppression is integrated into the existing KUnit hooks infrastructure
in test-bug.h, reusing the kunit_running static branch for zero
overhead when no tests are running.
Suppression is checked at three points in the warning path:
- In warn_slowpath_fmt(), the check runs before any output, fully
suppressing both message and backtrace. This covers architectures
without __WARN_FLAGS.
- In __warn_printk(), the check suppresses the warning message text.
This covers architectures that define __WARN_FLAGS but not their own
__WARN_printf (arm64, loongarch, parisc, powerpc, riscv, sh), where
the message is printed before the trap enters __report_bug().
- In __report_bug(), the check runs before __warn() is called,
suppressing the backtrace and stack dump.
To avoid double-counting on architectures where both __warn_printk()
and __report_bug() run for the same warning, kunit_is_suppressed_warning()
takes a bool parameter: true to increment the suppression counter
(used in warn_slowpath_fmt and __report_bug), false to check only
(used in __warn_printk).
The suppression state is dynamically allocated via kunit_kzalloc() and
tied to the KUnit test lifecycle via kunit_add_action(), ensuring
automatic cleanup at test exit. Writer-side access to the global
suppression list is serialized with a spinlock; readers use RCU.
Two API forms are provided:
- kunit_warning_suppress(test) { ... }: scoped, uses __cleanup for
automatic teardown on scope exit, kunit_add_action() as safety net
for abnormal exits (e.g. kthread_exit from failed assertions).
Suppression handle is only accessible inside the block.
- kunit_start/end_suppress_warning(test): direct functions returning
an explicit handle, for retaining the handle within the test,
or for cross-function usage.
Link: https://lore.kernel.org/r/20260514-kunit_add_support-v11-1-b36a530a6d8f@redhat.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Alessandro Carminati <acarmina@redhat.com>
Reviewed-by: Kees Cook <kees@kernel.org>
Reviewed-by: David Gow <david@davidgow.net>
Signed-off-by: Albert Esteve <aesteve@redhat.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
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Merge tag 'audit-pr-20260513' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/audit
Pull audit fixes from Paul Moore:
- Correctly log the inheritable capabilities
- Honor AUDIT_LOCKED in the AUDIT_TRIM and AUDIT_MAKE_EQUIV commands
* tag 'audit-pr-20260513' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/audit:
audit: enforce AUDIT_LOCKED for AUDIT_TRIM and AUDIT_MAKE_EQUIV
audit: fix incorrect inheritable capability in CAPSET records
The 'dumpability' of a task is fundamentally about the memory image of
the task - the concept comes from whether it can core dump or not - and
makes no sense when you don't have an associated mm.
And almost all users do in fact use it only for the case where the task
has a mm pointer.
But we have one odd special case: ptrace_may_access() uses 'dumpable' to
check various other things entirely independently of the MM (typically
explicitly using flags like PTRACE_MODE_READ_FSCREDS). Including for
threads that no longer have a VM (and maybe never did, like most kernel
threads).
It's not what this flag was designed for, but it is what it is.
The ptrace code does check that the uid/gid matches, so you do have to
be uid-0 to see kernel thread details, but this means that the
traditional "drop capabilities" model doesn't make any difference for
this all.
Make it all make a *bit* more sense by saying that if you don't have a
MM pointer, we'll use a cached "last dumpability" flag if the thread
ever had a MM (it will be zero for kernel threads since it is never
set), and require a proper CAP_SYS_PTRACE capability to override.
Reported-by: Qualys Security Advisory <qsa@qualys.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Kees Cook <kees@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
percpu_array_map_ops.map_meta_equal points to the generic
bpf_map_meta_equal(), which does not compare max_entries. When a
percpu array serves as an inner map, replacing it with one that has
fewer max_entries bypasses the check. Since percpu_array_map_gen_lookup()
inlines the original template's index_mask as a JIT immediate, a lookup
on the replacement map can access pptrs[] out of bounds.
Point percpu_array_map_ops.map_meta_equal to array_map_meta_equal(),
which already enforces the max_entries equality check.
Add a selftest to verify that replacing a percpu array inner map with
a differently-sized one is rejected.
Fixes: db69718b8e ("bpf: inline bpf_map_lookup_elem() for PERCPU_ARRAY maps")
Signed-off-by: Guannan Wang <wgnbuaa@gmail.com>
Acked-by: Mykyta Yatsenko <yatsenko@meta.com>
Link: https://lore.kernel.org/r/20260514074454.77491-1-wgnbuaa@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Rework the general infrastructure around RANDOM_KMALLOC_CACHES into more
flexible KMALLOC_PARTITION_CACHES, with the former being a partitioning
mode of the latter.
Introduce a new mode, KMALLOC_PARTITION_TYPED, which leverages a feature
available in Clang 22 and later, called "allocation tokens" via
__builtin_infer_alloc_token() [1]. Unlike KMALLOC_PARTITION_RANDOM
(formerly RANDOM_KMALLOC_CACHES), this mode deterministically assigns a
slab cache to an allocation of type T, regardless of allocation site.
The builtin __builtin_infer_alloc_token(<malloc-args>, ...) instructs
the compiler to infer an allocation type from arguments commonly passed
to memory-allocating functions and returns a type-derived token ID. The
implementation passes kmalloc-args to the builtin: the compiler performs
best-effort type inference, and then recognizes common patterns such as
`kmalloc(sizeof(T), ...)`, `kmalloc(sizeof(T) * n, ...)`, but also
`(T *)kmalloc(...)`. Where the compiler fails to infer a type the
fallback token (default: 0) is chosen.
Note: kmalloc_obj(..) APIs fix the pattern how size and result type are
expressed, and therefore ensures there's not much drift in which
patterns the compiler needs to recognize. Specifically, kmalloc_obj()
and friends expand to `(TYPE *)KMALLOC(__obj_size, GFP)`, which the
compiler recognizes via the cast to TYPE*.
Clang's default token ID calculation is described as [1]:
typehashpointersplit: This mode assigns a token ID based on the hash
of the allocated type's name, where the top half ID-space is reserved
for types that contain pointers and the bottom half for types that do
not contain pointers.
Separating pointer-containing objects from pointerless objects and data
allocations can help mitigate certain classes of memory corruption
exploits [2]: attackers who gains a buffer overflow on a primitive
buffer cannot use it to directly corrupt pointers or other critical
metadata in an object residing in a different, isolated heap region.
It is important to note that heap isolation strategies offer a
best-effort approach, and do not provide a 100% security guarantee,
albeit achievable at relatively low performance cost. Note that this
also does not prevent cross-cache attacks: while waiting for future
features like SLAB_VIRTUAL [3] to provide physical page isolation, this
feature should be deployed alongside SHUFFLE_PAGE_ALLOCATOR and
init_on_free=1 to mitigate cross-cache attacks and page-reuse attacks as
much as possible today.
With all that, my kernel (x86 defconfig) shows me a histogram of slab
cache object distribution per /proc/slabinfo (after boot):
<slab cache> <objs> <hist>
kmalloc-part-15 1465 ++++++++++++++
kmalloc-part-14 2988 +++++++++++++++++++++++++++++
kmalloc-part-13 1656 ++++++++++++++++
kmalloc-part-12 1045 ++++++++++
kmalloc-part-11 1697 ++++++++++++++++
kmalloc-part-10 1489 ++++++++++++++
kmalloc-part-09 965 +++++++++
kmalloc-part-08 710 +++++++
kmalloc-part-07 100 +
kmalloc-part-06 217 ++
kmalloc-part-05 105 +
kmalloc-part-04 4047 ++++++++++++++++++++++++++++++++++++++++
kmalloc-part-03 183 +
kmalloc-part-02 283 ++
kmalloc-part-01 316 +++
kmalloc 1422 ++++++++++++++
The above /proc/slabinfo snapshot shows me there are 6673 allocated
objects (slabs 00 - 07) that the compiler claims contain no pointers or
it was unable to infer the type of, and 12015 objects that contain
pointers (slabs 08 - 15). On a whole, this looks relatively sane.
Additionally, when I compile my kernel with -Rpass=alloc-token, which
provides diagnostics where (after dead-code elimination) type inference
failed, I see 186 allocation sites where the compiler failed to identify
a type (down from 966 when I sent the RFC [4]). Some initial review
confirms these are mostly variable sized buffers, but also include
structs with trailing flexible length arrays.
Link: https://clang.llvm.org/docs/AllocToken.html [1]
Link: https://blog.dfsec.com/ios/2025/05/30/blasting-past-ios-18/ [2]
Link: https://lwn.net/Articles/944647/ [3]
Link: https://lore.kernel.org/all/20250825154505.1558444-1-elver@google.com/ [4]
Link: https://discourse.llvm.org/t/rfc-a-framework-for-allocator-partitioning-hints/87434
Acked-by: GONG Ruiqi <gongruiqi1@huawei.com>
Co-developed-by: Harry Yoo (Oracle) <harry@kernel.org>
Signed-off-by: Harry Yoo (Oracle) <harry@kernel.org>
Signed-off-by: Marco Elver <elver@google.com>
Reviewed-by: Harry Yoo (Oracle) <harry@kernel.org>
Link: https://patch.msgid.link/20260511200136.3201646-1-elver@google.com
Signed-off-by: Vlastimil Babka (SUSE) <vbabka@kernel.org>
We've hit the 512 bytes limit on stack depth a few times in Cilium
recently. As a result, we started reporting in CI our current maximum
stack depth across all configurations for each BPF program.
Unfortunately, that is not trivial to compute in userspace. The
verifier reports the stack depths of individual subprogs at the end of
the logs. However the maximum combined stack depth also depends on the
callgraph of those subprogs (the max combined stack depth is the height
of the callgraph weighted by per-subprog stack depths). We can compute
a callgraph in userspace from the loaded instructions, but it often
doesn't match the verifier's own callgraph because of dead code
elimination. Our current approach relies on dumping the BPF_LOG_LEVEL2
logs, but this feels overkill considering the verifier already has the
information we need.
The patch lets the verifier dump the maximum combined stack depth in
the logs, on the same line as the per-subprog stack depths:
stack depth 16+256 max 272
The per-subprog stack depths and the new max stack depth are not
directly comparable. The former is sometimes updated during fixups,
while the latter is not. As a result, even with a single subprog, we
may end up with two slightly different values. The aim of the new max
value is to be closest to what is actually enforced by the verifier.
Signed-off-by: Paul Chaignon <paul.chaignon@gmail.com>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/d3d23a0410f87f116f3bbaa98a815dbae113bda2.1778700777.git.paul.chaignon@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Bulk is hardening of the new sub-scheduler infrastructure.
- UAFs and lifecycle bugs on the sub-sched attach/detach paths: parent
sub_kset freed under a racing child, list_del_rcu on an uninitialized
list head, ops->priv stomped by concurrent attach/detach, and a UAF in
the init-failure error path.
- Task state-machine reorg closing concurrent enable-vs-dead races: a
task exiting during the unlocked init window could trip NULL ops
derefs or skip exit_task() cleanup.
- A scx_link_sched() self-deadlock on scx_sched_lock.
- isolcpus: stop dereferencing the now-RCU-protected HK_TYPE_DOMAIN
cpumask without RCU, and stop rejecting BPF schedulers when only
cpuset isolated partitions are active.
- PREEMPT_RT: disable irq_work runs in hardirq context so dumps show the
failing task rather than the irq_work kthread.
- Assorted !CONFIG_EXT_SUB_SCHED, randconfig, and selftest build fixes.
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Merge tag 'sched_ext-for-7.1-rc3-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/sched_ext
Pull sched_ext fixes from Tejun Heo:
"The bulk of this is hardening of the new sub-scheduler infrastructure.
- UAFs and lifecycle bugs on the sub-sched attach/detach paths:
parent sub_kset freed under a racing child, list_del_rcu on an
uninitialized list head, ops->priv stomped by concurrent
attach/detach, and a UAF in the init-failure error path
- Task state-machine reorg closing concurrent enable-vs-dead races: a
task exiting during the unlocked init window could trip NULL ops
derefs or skip exit_task() cleanup
- A scx_link_sched() self-deadlock on scx_sched_lock
- isolcpus: stop dereferencing the now-RCU-protected HK_TYPE_DOMAIN
cpumask without RCU, and stop rejecting BPF schedulers when only
cpuset isolated partitions are active
- PREEMPT_RT: disable irq_work runs in hardirq context so dumps show
the failing task rather than the irq_work kthread
- Assorted !CONFIG_EXT_SUB_SCHED, randconfig, and selftest build
fixes"
* tag 'sched_ext-for-7.1-rc3-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/sched_ext:
sched_ext: Use HK_TYPE_DOMAIN_BOOT to detect isolcpus= domain isolation
sched_ext: Defer sub_kset base put to scx_sched_free_rcu_work
sched_ext: INIT_LIST_HEAD() &sch->all in scx_alloc_and_add_sched()
sched_ext: Drop NONE early return in scx_disable_and_exit_task()
sched_ext: Avoid UAF in scx_root_enable_workfn() init failure path
sched_ext: Clear ops->priv on scx_alloc_and_add_sched() error paths
sched_ext: Fix ops->priv clobber on concurrent attach/detach
selftests/sched_ext: Fix build error in dequeue selftest
sched_ext: Handle SCX_TASK_NONE in disable/switched_from paths
sched_ext: Close sub-sched init race with post-init DEAD recheck
sched_ext: Close root-enable vs sched_ext_dead() race with SCX_TASK_INIT_BEGIN
sched_ext: Replace SCX_TASK_OFF_TASKS flag with SCX_TASK_DEAD state
sched_ext: Inline scx_init_task() and move RESET_RUNNABLE_AT into scx_set_task_state()
sched_ext: Cleanups in preparation for the SCX_TASK_INIT_BEGIN/DEAD work
sched_ext: Use IRQ_WORK_INIT_HARD() to initialize sch->disable_irq_work
sched_ext: Fix !CONFIG_EXT_SUB_SCHED build warnings
sched_ext: Drop unused scx_find_sub_sched() stub
sched_ext: Move scx_error() out of scx_link_sched()'s lock region
- cpuset fixes:
- Partition invalidation could return CPUs still in use by sibling
partitions, producing overlapping effective_cpus.
- cpuset_can_attach() over-reserved DL bandwidth on moves that stayed
within the same root domain.
- Pending DL migration state leaked into later attaches when a later
can_attach() check failed.
- Reorder PF_EXITING and __GFP_HARDWALL checks so dying tasks can
allocate from any node and exit quickly.
- dmem: propagate -ENOMEM instead of spinning forever when the fallback
pool allocation also fails.
- selftests/cgroup: percpu test error-path leak, bogus numeric
comparison of cpuset strings, and a zero-length read() that silently
passed OOM-kill tests.
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Merge tag 'cgroup-for-7.1-rc3-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup
Pull cgroup fixes from Tejun Heo:
- cpuset fixes:
- Partition invalidation could return CPUs still in use by sibling
partitions, producing overlapping effective_cpus
- cpuset_can_attach() over-reserved DL bandwidth on moves that
stayed within the same root domain
- Pending DL migration state leaked into later attaches when a
later can_attach() check failed
- Reorder PF_EXITING and __GFP_HARDWALL checks so dying tasks can
allocate from any node and exit quickly
- dmem: propagate -ENOMEM instead of spinning forever when the fallback
pool allocation also fails
- selftests/cgroup: percpu test error-path leak, bogus numeric
comparison of cpuset strings, and a zero-length read() that silently
passed OOM-kill tests
* tag 'cgroup-for-7.1-rc3-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
cgroup/cpuset: Return only actually allocated CPUs during partition invalidation
selftests/cgroup: Fix error path leaks in test_percpu_basic
cgroup/cpuset: Reserve DL bandwidth only for root-domain moves
cgroup/cpuset: Reset DL migration state on can_attach() failure
selftests/cgroup: Fix string comparison in write_test
selftests/cgroup: Fix cg_read_strcmp() empty string comparison
cgroup/dmem: Return -ENOMEM on failed pool preallocation
cgroup/cpuset: move PF_EXITING check before __GFP_HARDWALL in cpuset_current_node_allowed()
- Plug a wq->cpu_pwq leak on the WQ_UNBOUND allocation failure path.
- Fix a cancel_delayed_work_sync() livelock against drain_workqueue()
caused by the drain/destroy reject path leaving WORK_STRUCT_PENDING set
with no owner.
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Merge tag 'wq-for-7.1-rc3-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq
Pull workqueue fixes from Tejun Heo:
- Plug a wq->cpu_pwq leak on the WQ_UNBOUND allocation failure path
- Fix a cancel_delayed_work_sync() livelock against drain_workqueue()
caused by the drain/destroy reject path leaving WORK_STRUCT_PENDING
set with no owner
* tag 'wq-for-7.1-rc3-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq:
workqueue: Fix wq->cpu_pwq leak in alloc_and_link_pwqs() WQ_UNBOUND path
workqueue: Release PENDING in __queue_work() drain/destroy reject path
__hrtimer_start_range_ns() has a bool return type, but returns actually
three different values, which are checked at the call site.
Make the return type int.
Fixes: bd5956166d ("hrtimer: Provide hrtimer_start_range_ns_user()")
Reported-by: Dan Carpenter <error27@gmail.com
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
scx_enable() refuses to attach a BPF scheduler when isolcpus=domain is
in effect by comparing housekeeping_cpumask(HK_TYPE_DOMAIN) against
cpu_possible_mask.
Since commit 27c3a5967f ("sched/isolation: Convert housekeeping
cpumasks to rcu pointers"), HK_TYPE_DOMAIN's cpumask is RCU protected
and dereferencing it requires either RCU read lock, the cpu_hotplug
write lock, or the cpuset lock; scx_enable() holds none of these, so
booting with isolcpus=domain and attaching any BPF scheduler triggers
the following lockdep splat:
=============================
WARNING: suspicious RCU usage
-----------------------------
kernel/sched/isolation.c:60 suspicious rcu_dereference_check() usage!
1 lock held by scx_flash/281:
#0: ffffffff8379fce0 (update_mutex){+.+.}-{4:4}, at:
bpf_struct_ops_link_create+0x134/0x1c0
Call Trace:
dump_stack_lvl+0x6f/0xb0
lockdep_rcu_suspicious.cold+0x37/0x70
housekeeping_cpumask+0xcd/0xe0
scx_enable.isra.0+0x17/0x120
bpf_scx_reg+0x5e/0x80
bpf_struct_ops_link_create+0x151/0x1c0
__sys_bpf+0x1e4b/0x33c0
__x64_sys_bpf+0x21/0x30
do_syscall_64+0x117/0xf80
entry_SYSCALL_64_after_hwframe+0x77/0x7f
In addition, commit 03ff735101 ("cpuset: Update HK_TYPE_DOMAIN cpumask
from cpuset") made HK_TYPE_DOMAIN include cpuset isolated partitions as
well, which means the current check also rejects BPF schedulers when a
cpuset partition is active. That contradicts the original intent of
commit 9f391f94a1 ("sched_ext: Disallow loading BPF scheduler if
isolcpus= domain isolation is in effect"), which explicitly noted that
cpuset partitions are honored through per-task cpumasks and should not
be rejected.
Switch to housekeeping_enabled(HK_TYPE_DOMAIN_BOOT), which reads only
the housekeeping flag bit (no RCU dereference) and reflects exactly the
boot-time isolcpus= configuration that the error message refers to.
Fixes: 27c3a5967f ("sched/isolation: Convert housekeeping cpumasks to rcu pointers")
Cc: stable@vger.kernel.org # v7.0+
Signed-off-by: Andrea Righi <arighi@nvidia.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Frederic Weisbecker <frederic@kernel.org>
In update_parent_effective_cpumask() with partcmd_invalidate, the CPUs
to return to the parent are computed as:
adding = cpumask_and(tmp->addmask, xcpus, parent->effective_xcpus);
where xcpus = user_xcpus(cs) which returns cs->exclusive_cpus (if set)
or cs->cpus_allowed. When exclusive_cpus is not set, user_xcpus(cs) can
contain CPUs that were never actually granted to the partition due to
sibling exclusion in compute_excpus(). Consequently, the invalidation
may return CPUs to the parent that remain in use by sibling partitions,
causing overlapping effective_cpus and triggering the
WARN_ON_ONCE(1) in generate_sched_domains().
Use cs->effective_xcpus instead, which reflects the CPUs actually
granted to this partition.
Reproducer (on a 4-CPU machine):
cd /sys/fs/cgroup
mkdir a1 b1
# a1 becomes partition root with CPUs 0-1
echo "0-1" > a1/cpuset.cpus
echo "root" > a1/cpuset.cpus.partition
# b1 becomes partition root with CPUs 1-2, but sibling exclusion
# reduces its effective_xcpus to CPU 2 only
echo "1-2" > b1/cpuset.cpus
echo "root" > b1/cpuset.cpus.partition
# b1 changes cpus_allowed to 0-1 -> partition invalidation
echo "0-1" > b1/cpuset.cpus
# Expected: CPUs 2-3 (only CPU 2 returned from b1)
# Actual: CPUs 1-3 (CPU 0-1 returned, overlapping with a1)
cat cpuset.cpus.effective
dmesg will also show a WARNING from generate_sched_domains() reporting
overlapping partition root effective_cpus.
Fixes: 2a3602030d ("cgroup/cpuset: Don't invalidate sibling partitions on cpuset.cpus conflict")
Cc: stable@vger.kernel.org # v7.0+
Signed-off-by: sunshaojie <sunshaojie@kylinos.cn>
Tested-by: Chen Ridong <chenridong@huaweicloud.com>
Reviewed-by: Chen Ridong <chenridong@huaweicloud.com>
Reviewed-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Add x86_64 JIT support for BPF functions and kfuncs with more than
5 arguments. The extra arguments are passed through a stack area
addressed by register r11 (BPF_REG_PARAMS) in BPF bytecode,
which the JIT translates to native code.
The JIT follows the x86-64 calling convention for both BPF-to-BPF
and kfunc calls:
- Arg 6 is passed in the R9 register
- Args 7+ are passed on the stack
Incoming arg 6 (BPF r11+8) is translated to a MOV from R9 rather
than a memory load. Incoming args 7+ (BPF r11+16, r11+24, ...) map
directly to [rbp + 16], [rbp + 24], ..., matching the x86-64 stack
layout after CALL + PUSH RBP, so no offset adjustment is needed.
tail_call_reachable is rejected by the verifier and priv_stack is
disabled by the JIT when stack args exist, so R9 is always
available. When BPF bytecode writes to the arg-6 stack slot
(offset -8), the JIT emits a MOV into R9 instead of a memory store.
Outgoing args 7+ are placed at [rsp] in a pre-allocated area below
callee-saved registers, using:
native_off = outgoing_arg_base - outgoing_rsp - bpf_off - 16
The native x86_64 stack layout with stack arguments:
high address
+-------------------------+
| incoming stack arg N | [rbp + 16 + (N-7)*8] (from caller)
| ... |
| incoming stack arg 7 | [rbp + 16]
+-------------------------+
| return address | [rbp + 8]
| saved rbp | [rbp]
+-------------------------+
| BPF program stack | (round_up(stack_depth, 8) bytes)
+-------------------------+
| callee-saved regs | (r12, rbx, r13, r14, r15 as needed)
+-------------------------+
| outgoing arg M | [rsp + (M-7)*8]
| ... |
| outgoing arg 7 | [rsp]
+-------------------------+ rsp
low address
Acked-by: Puranjay Mohan <puranjay@kernel.org>
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20260513045122.2393118-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Other architectures like arm64, riscv, etc. have enough register
and for them private stack can be used together with
stack arguments.
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20260513045114.2392291-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Tail calls are deprecated and will be replaced by indirect calls
in the future. Reject programs that combine tail calls with stack
arguments rather than adding complexity for a deprecated feature.
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20260513045109.2392108-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Extend the stack argument mechanism to kfunc calls, allowing kfuncs
with more than 5 parameters to receive additional arguments via the
r11-based stack arg area.
For kfuncs, the caller is a BPF program and the callee is a kernel
function. The BPF program writes outgoing args at negative r11
offsets, following the same convention as BPF-to-BPF calls:
Outgoing: r11 - 8 (arg6), ..., r11 - N*8 (last arg)
The following is an example:
int foo(int a1, int a2, int a3, int a4, int a5, int a6, int a7) {
...
kfunc1(a1, a2, a3, a4, a5, a6, a7, a8);
...
kfunc2(a1, a2, a3, a4, a5, a6, a7, a8, a9);
...
}
Caller (foo), generated by llvm
===============================
Incoming (positive offsets):
r11+8: [incoming arg 6]
r11+16: [incoming arg 7]
Outgoing for kfunc1 (negative offsets):
r11-8: [outgoing arg 6]
r11-16: [outgoing arg 7]
r11-24: [outgoing arg 8]
Outgoing for kfunc2 (negative offsets):
r11-8: [outgoing arg 6]
r11-16: [outgoing arg 7]
r11-24: [outgoing arg 8]
r11-32: [outgoing arg 9]
Later JIT will marshal outgoing arguments to the native calling
convention for kfunc1() and kfunc2().
For kfunc calls where stack args are used as constant or size
parameters, a mark_stack_arg_precision() helper is used to propagate
precision and do proper backtracking.
There are two places where meta->release_regno needs to keep
regno for later releasing the reference. Also, 'cur_aux(env)->arg_prog = regno'
is also keeping regno for later fixup. Since stack arguments don't have a valid
register number (regno is negative), these three cases are rejected for now
if the argument is on the stack.
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20260513045104.2391543-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
BPF_REG_PARAMS (r11) is used for stack argument accesses and
the following are only insns with r11 presence:
- load incoming stack arg
- store register to outgoing stack arg
- store immediate to outgoing stack arg
The detailed insn format can be found in is_stack_arg_ldx/st/stx()
helpers. After this patch, stack arg ldx/st/stx insns become valid
for kernel and these insns can be properly checked by verifier.
The LLVM compiler [1] implemented the above BPF_REG_PARAMS insns.
[1] https://github.com/llvm/llvm-project/pull/189060
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20260513045059.2391192-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Add bpf_jit_supports_stack_args() as a weak function defaulting to
false. Architectures that implement JIT support for stack arguments
override it to return true.
Reject BPF functions with more than 5 parameters at verification
time if the architecture does not support stack arguments.
Acked-by: Puranjay Mohan <puranjay@kernel.org>
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20260513045054.2390945-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
The interpreter does not understand the bpf register r11
(BPF_REG_PARAMS) used for stack arguments. So reject interpreter
usage if stack arguments are used either in the main program or
any subprogram.
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20260513045049.2390444-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
BPF_REG_PARAMS (R11) is at index MAX_BPF_REG, which is beyond the
register tracking arrays in const_fold.c and liveness.c. Handle it
explicitly to avoid out-of-bounds accesses.
Extend the arg tracking dataflow to cover stack arg slots. Otherwise,
pointers passed through stack args are invisible to liveness, causing
the pointed-to stack slots to be incorrectly poisoned.
Extend the at_out tracking array to MAX_AT_TRACK_REGS (registers
plus stack arg slots) so that outgoing stack arg stores are tracked
alongside registers. Add a separate at_stack_arg_entry array in
compute_subprog_args(), passed to arg_track_xfer(), to restore
FP-derived values on incoming stack arg reads.
Extend record_call_access() to check stack arg slots for FP-derived
pointers at kfunc call sites, reusing the record_arg_access() helper
extracted in the previous patch. Pass stack arg state from caller to
callee in analyze_subprog() so that callees can track pointers received
through stack args, hence avoid poisoning.
Skip stack arg instructions in record_load_store_access(). Stack arg
STX uses dst_reg=BPF_REG_PARAMS (index 11), but at[11] is repurposed
to track the value stored in stack arg slot 0. Without the skip, if a
prior stack arg STX stored an FP-derived pointer (e.g., fp-64) into
slot 0, a subsequent stack arg STX would read that FP-derived value as
the base pointer and spuriously mark a regular stack slot (e.g., fp-72
from -64 + -8) as accessed in the liveness bitmap.
Extend arg_track_log() to log state transitions for outgoing stack arg
slots at indices MAX_BPF_REG through MAX_AT_TRACK_REGS-1. Without this,
changes to at_out[11..17] caused by stack arg store instructions are
silently omitted from BPF_LOG_LEVEL2 output. For example, when a
caller passes fp-64 through a stack argument:
subprog#0:
10: (bf) r6 = r10
11: (07) r6 += -64
12: (7b) *(u64 *)(r11 -8) = r6
sa0: none -> fp0-64
13: (85) call pc+5
Without the fix, the "sa0: none -> fp0-64" transition at insn 12
would not appear.
Extend print_subprog_arg_access() to include stack arg slots in the
per-instruction FP-derived state dump. For example:
subprog#0:
12: (7b) *(u64 *)(r11 - 8) = r6 // r6=fp0-64
13: (85) call pc+5 // r6=fp0-64 sa0=fp0-64
Without the fix, the "sa0=fp0-64" annotation at insn 13 would not
appear, making it harder to debug liveness analysis for programs
that pass FP-derived pointers through stack arguments.
Extend has_fp_args() to also check stack arg slots for FP-derived
pointers, so that callees receiving pointers only through stack args
are still recursively analyzed.
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20260513045043.2389049-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Replace "frame != ARG_NONE" with arg_is_fp() in has_fp_args().
The function's purpose is to check whether any argument is derived
from a frame pointer, which is exactly what arg_is_fp() tests
(frame >= 0 || frame == ARG_IMPRECISE). Using the dedicated
predicate is clearer and more consistent with the rest of the file.
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20260513045035.2388671-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Extract the per-argument FP-derived pointer handling from
record_call_access() into a new record_arg_access() helper.
The existing loop body — checking arg_is_fp, querying stack access
bytes, and calling record_stack_access/record_imprecise — will be
reused for stack argument slots in the next patch. Factoring it out
now avoids duplicating the logic.
No functional change.
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20260513045030.2388067-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Extend the precision marking and backtracking infrastructure to
support stack argument slots (r11-based accesses). Without this,
precision demands for scalar values passed through stack arguments
are silently dropped, which could allow the verifier to incorrectly
prune states with different constant values in stack arg slots.
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20260513045025.2387526-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Move stack slot index (spi) and frame number out of the flags field
in bpf_jmp_history_entry into dedicated bitfields. This simplifies
the encoding and makes room for new flags.
Previously, spi and frame were packed into the lower 9 bits of the
12-bit flags field (3 bits frame + 6 bits spi), with INSN_F_STACK_ACCESS
at BIT(9) and INSN_F_DST/SRC_REG_STACK at BIT(10)/BIT(11).
But this has no room for an INSN_F_* flag for stack arguments.
To resolve this issue, bpf_jmp_history_entry field idx is narrowed to
20 bits (sufficient for insn indices up to 1M), and the freed bits hold
spi (6 bits) and frame (3 bits) as dedicated struct fields. The flags
enum is simplified accordingly:
INSN_F_STACK_ACCESS -> BIT(0)
INSN_F_DST_REG_STACK -> BIT(1)
INSN_F_SRC_REG_STACK -> BIT(2)
which allows more room for additional INSN_F_* flags.
bpf_push_jmp_history() now takes explicit spi and frame parameters
instead of encoding them into flags. The insn_stack_access_flags(),
insn_stack_access_spi(), and insn_stack_access_frameno() helpers are
removed.
No functional change.
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20260513045020.2385962-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Currently BPF functions (subprogs) are limited to 5 register arguments.
With [1], the compiler can emit code that passes additional arguments
via a dedicated stack area through bpf register BPF_REG_PARAMS (r11),
introduced in an earlier patch ([2]).
The compiler uses positive r11 offsets for incoming (callee-side) args
and negative r11 offsets for outgoing (caller-side) args, following the
x86_64/arm64 calling convention direction. There is an 8-byte gap at
offset 0 separating two regions:
Incoming (callee reads): r11+8 (arg6), r11+16 (arg7), ...
Outgoing (caller writes): r11-8 (arg6), r11-16 (arg7), ...
The following is an example to show how stack arguments are saved
and transferred between caller and callee:
int foo(int a1, int a2, int a3, int a4, int a5, int a6, int a7) {
...
bar(a1, a2, a3, a4, a5, a6, a7, a8);
...
}
Caller (foo) Callee (bar)
============ ============
Incoming (positive offsets): Incoming (positive offsets):
r11+8: [incoming arg 6] r11+8: [incoming arg 6] <-+
r11+16: [incoming arg 7] r11+16: [incoming arg 7] <-|+
r11+24: [incoming arg 8] <-||+
Outgoing (negative offsets): |||
r11-8: [outgoing arg 6 to bar] -------->-------------------------+||
r11-16: [outgoing arg 7 to bar] -------->--------------------------+|
r11-24: [outgoing arg 8 to bar] -------->---------------------------+
If the bpf function has more than one call:
int foo(int a1, int a2, int a3, int a4, int a5, int a6, int a7) {
...
bar1(a1, a2, a3, a4, a5, a6, a7, a8);
...
bar2(a1, a2, a3, a4, a5, a6, a7, a8, a9);
...
}
Caller (foo) Callee (bar2)
============ ==============
Incoming (positive offsets): Incoming (positive offsets):
r11+8: [incoming arg 6] r11+8: [incoming arg 6] <+
r11+16: [incoming arg 7] r11+16: [incoming arg 7] <|+
r11+24: [incoming arg 8] <||+
Outgoing for bar2 (negative offsets): r11+32: [incoming arg 9] <|||+
r11-8: [outgoing arg 6] ---->----------->-------------------------+|||
r11-16: [outgoing arg 7] ---->----------->--------------------------+||
r11-24: [outgoing arg 8] ---->----------->---------------------------+|
r11-32: [outgoing arg 9] ---->----------->----------------------------+
The verifier tracks outgoing stack arguments in stack_arg_regs[] and
out_stack_arg_cnt in bpf_func_state, separately from the regular
r10 stack. The callee does not copy incoming args — it reads them
directly from the caller's outgoing slots at positive r11 offsets.
Similar to stacksafe(), introduce stack_arg_safe() to do pruning
check.
Outgoing stack arg slots are invalidated when the callee returns
(e.g. in prepare_func_exit), not at call time. This allows the callee to
read incoming args from the caller's outgoing slots during
verification. The following are a few examples.
Example 1:
*(u64 *)(r11 - 8) = r6;
*(u64 *)(r11 - 16) = r7;
call bar1; // arg6 = r6, arg7 = r7
call bar2; // expected with 2 stack arguments, failed
Example 2:
To fix the Example 1:
*(u64 *)(r11 - 8) = r6;
*(u64 *)(r11 - 16) = r7;
call bar1; // arg6 = r6, arg7 = r7
*(u64 *)(r11 - 8) = r8;
*(u64 *)(r11 - 16) = r9;
call bar2; // arg6 = r8, arg7 = r9
Example 3:
The compiler can hoist the shared stack arg stores above the branch:
*(u64 *)(r11 - 16) = r7;
if cond goto else;
*(u64 *)(r11 - 8) = r8;
call bar1; // arg6 = r8, arg7 = r7
goto end;
else:
*(u64 *)(r11 - 8) = r9;
call bar2; // arg6 = r9, arg7 = r7
end:
Example 4:
Within a loop:
loop:
*(u64 *)(r11 - 8) = r6; // arg6, before loop
call bar; // reuses arg6 each iteration
if ... goto loop;
A separate max_out_stack_arg_cnt field in bpf_subprog_info tracks
the deepest outgoing slot actually written. This intends to
reject programs that write to slots beyond what any callee expects.
It is necessary for JIT.
Similar to typical compiler generated code, enforce the following
orderings:
- all stack arg reads must be ahead of any stack arg write
- all stack arg reads must be before any bpf func, kfunc and helpers
This is needed as JIT may emit 'mov' insns for read/write with
the same register and bpf function, kfunc and helper will invalidate
all arguments immediately after the call.
Callback functions with stack arguments need kernel setup parameter
types (including stack parameters) properly and then callback function
can retrieve such information for verification purpose.
Global subprogs and freplace with >5 args are not yet supported.
[1] https://github.com/llvm/llvm-project/pull/189060
[2] https://lore.kernel.org/bpf/20260423033506.2542005-1-yonghong.song@linux.dev/
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20260513045015.2385013-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Move the "sub->arg_cnt = nargs" assignment to immediately after
nargs is computed from btf_type_vlen(), instead of at the end of
btf_prepare_func_args().
btf_prepare_func_args() can return -EINVAL early in several cases,
e.g. when a static function has some non-int/enum arguments.
Since -EINVAL from btf_prepare_func_args() does not immediately
reject verification, arg_cnt remains zero after the early return.
This causes later stack argument based load/store insns to
incorrectly assume the function has no arguments.
Setting arg_cnt right after nargs ensures it is available regardless
of which path btf_prepare_func_args() takes.
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20260513045010.2384635-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Remove the copy_register_state() helper which was just a plain struct
assignment wrapper and replace all call sites with direct struct
assignment. This simplifies the code in preparation for upcoming stack
argument support.
No functional change.
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20260513045000.2382933-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
A few fixes for kexec handover and liveupdate:
* make sure KHO is skipped for crash kernel
* fix error reporting in memfd preservation if it fails mid-loop
* don't allow preserving memfds whose page count exceeds UINT_MAX
* fix documentation of memfd seals preservation to match the code
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Merge tag 'fixes-2026-05-13' of git://git.kernel.org/pub/scm/linux/kernel/git/liveupdate/linux
Pull liveupdate fixes from Mike Rapoport:
"A few fixes for kexec handover and liveupdate:
- make sure KHO is skipped for crash kernel
- fix error reporting in memfd preservation if it fails mid-loop
- don't allow preserving memfds whose page count exceeds UINT_MAX
- fix documentation of memfd seals preservation to match the code"
* tag 'fixes-2026-05-13' of git://git.kernel.org/pub/scm/linux/kernel/git/liveupdate/linux:
mm/memfd_luo: document preservation of file seals
mm/memfd_luo: reject memfds whose page count exceeds UINT_MAX
mm/memfd_luo: report error when restoring a folio fails mid-loop
kho: skip KHO for crash kernel
scx_sub_enable_workfn() pins parent->kobj before dropping scx_sched_lock,
but that does not pin parent->sub_kset. Concurrent disable can
kset_unregister and free sub_kset before scx_alloc_and_add_sched()
dereferences it.
Split sub_kset teardown: kobject_del() at disable keeps sysfs removal; defer
kobject_put() to scx_sched_free_rcu_work so the memory survives. A racing
child sees state_in_sysfs=0 with valid memory, sysfs_create_dir() fails, and
the existing exit_kind gate in scx_link_sched() turns it away with -ENOENT.
Fixes: 411d3ef1a7 ("sched_ext: Unregister sub_kset on scheduler disable")
Signed-off-by: Tejun Heo <tj@kernel.org>
On scx_link_sched() error paths (parent disabled, hash insert failure),
&sch->all is never added to scx_sched_all. The cleanup path runs
scx_unlink_sched() unconditionally, which calls list_del_rcu(&sch->all) on a
list_head that was never initialized triggering a corruption warning.
Initialize &sch->all.
Fixes: 54be8de423 ("sched_ext: Factor out scx_link_sched() and scx_unlink_sched()")
Signed-off-by: Tejun Heo <tj@kernel.org>
d3e73a0808 ("sched_ext: Handle SCX_TASK_NONE in disable/switched_from
paths") skipped the trailing scx_set_task_sched(p, NULL) on NONE tasks.
After scx_fail_parent() parks a task at NONE/sched=parent and the parent
is later freed via queue_rcu_work() during root_disable, the preserved
p->scx.sched dangles - print_scx_info() from sched_show_task() reads
sch->ops.name from freed memory.
Drop the early return. __scx_disable_and_exit_task() already short-
circuits on NONE and the SUB_INIT block was cleared by
scx_fail_parent()'s earlier call, so clearing p->scx.sched is the only
work left - and the one thing the path actually needs.
v2: Extend the SUB_INIT block comment to note that the flag is only
set on the sub-enable path, so it's always clear on the NONE
re-entry (Andrea).
Fixes: d3e73a0808 ("sched_ext: Handle SCX_TASK_NONE in disable/switched_from paths")
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Andrea Righi <arighi@nvidia.com>
AUDIT_ADD_RULE and AUDIT_DEL_RULE correctly check for AUDIT_LOCKED
and return -EPERM, but AUDIT_TRIM and AUDIT_MAKE_EQUIV do not. This
allows a process with CAP_AUDIT_CONTROL to modify directory tree
watches and equivalence mappings even when the audit configuration
has been locked, undermining the purpose of the lock.
Add AUDIT_LOCKED checks to both commands.
Cc: stable@vger.kernel.org
Reviewed-by: Ricardo Robaina <rrobaina@redhat.com>
Assisted-by: Claude:claude-opus-4-6
Signed-off-by: Sergio Correia <scorreia@redhat.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
__audit_log_capset() records the effective capability set into the
inheritable field due to a copy-paste error. Every CAPSET audit
record therefore reports cap_pi (process inheritable) with the value
of cap_effective instead of cap_inheritable.
This silently corrupts audit data used for compliance and forensic
analysis: an attacker who modifies inheritable capabilities to
prepare for a privilege-escalating exec would have the change masked
in the audit trail.
The bug has been present since the original introduction of CAPSET
audit records in 2008.
Cc: stable@vger.kernel.org
Fixes: e68b75a027 ("When the capset syscall is used it is not possible for audit to record the actual capbilities being added/removed. This patch adds a new record type which emits the target pid and the eff, inh, and perm cap sets.")
Reviewed-by: Ricardo Robaina <rrobaina@redhat.com>
Assisted-by: Claude:claude-opus-4-6
Signed-off-by: Sergio Correia <scorreia@redhat.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
Many BPF_MAP_CREATE validation failures currently return -EINVAL without
any explanation to userspace.
Plumb common syscall log attributes into map_create(), create a verifier
log from bpf_common_attr::log_buf/log_size/log_level, and report
map-creation failure reasons through that buffer.
This improves debuggability by allowing userspace to inspect why map
creation failed and read back log_true_size from common attributes.
Signed-off-by: Leon Hwang <leon.hwang@linux.dev>
Link: https://lore.kernel.org/r/20260512153157.28382-7-leon.hwang@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
BPF_BTF_LOAD can now take log parameters from both union bpf_attr and
struct bpf_common_attr, with the same merge rules as BPF_PROG_LOAD:
- if both sides provide a complete log tuple (buf/size/level) and they
match, use it;
- if only one side provides log parameters, use that one;
- if both sides provide complete tuples but they differ, return -EINVAL.
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Leon Hwang <leon.hwang@linux.dev>
Link: https://lore.kernel.org/r/20260512153157.28382-6-leon.hwang@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
BPF_PROG_LOAD can now take log parameters from both union bpf_attr and
struct bpf_common_attr. The merge rules are:
- if both sides provide a complete log tuple (buf/size/level) and they
match, use it;
- if only one side provides log parameters, use that one;
- if both sides provide complete tuples but they differ, return -EINVAL.
Signed-off-by: Leon Hwang <leon.hwang@linux.dev>
Link: https://lore.kernel.org/r/20260512153157.28382-5-leon.hwang@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
The next commit will add support for reporting logs via extended common
attributes, including 'log_true_size'.
To prepare for that, refactor the 'log_true_size' reporting logic by
introducing a new struct bpf_log_attr to encapsulate log-related behavior:
* bpf_log_attr_init(): initialize log fields, which will support
extended common attributes in the next commit.
* bpf_log_attr_finalize(): handle log finalization and write back
'log_true_size' to userspace.
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Leon Hwang <leon.hwang@linux.dev>
Link: https://lore.kernel.org/r/20260512153157.28382-4-leon.hwang@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Add generic BPF syscall support for passing common attributes.
The initial set of common attributes includes:
1. 'log_buf': User-provided buffer for storing logs.
2. 'log_size': Size of the log buffer.
3. 'log_level': Log verbosity level.
4. 'log_true_size': Actual log size reported by kernel.
The common-attribute pointer and its size are passed as the 4th and 5th
syscall arguments. A new command bit, 'BPF_COMMON_ATTRS' ('1 << 16'),
indicates that common attributes are supplied.
This commit adds syscall and uapi plumbing. Command-specific handling is
added in follow-up patches.
Signed-off-by: Leon Hwang <leon.hwang@linux.dev>
Link: https://lore.kernel.org/r/20260512153157.28382-2-leon.hwang@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
- kprobes: skip non-symbol addresses in kprobe_add_ksym_blacklist()
Since the ftrace adds its NOPs at .kprobes.text section (which stores
an array), a wrong entry is added when loading a module which uses
"__kprobes" attribute. To solve this, add "notrace" to __kprobes
functions.
- test_kprobes: clear kprobes between test runs
Clear all kprobes in the test program after running a test set,
because Kunit test can run several times.
- fprobe: Fix unregister_fprobe() to wait for RCU grace period
Since the fprobe data structure is removed with hlist_del_rcu(), it
should wait for the RCU grace period. If the caller waits for RCU,
we can use the async variant (e.g. eBPF)
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Merge tag 'probes-fixes-v7.1-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace
Pull probes fixes from Masami Hiramatsu:
- kprobes: skip non-symbol addresses in kprobe_add_ksym_blacklist()
Since the ftrace adds its NOPs at .kprobes.text section (which stores
an array), a wrong entry is added when loading a module which uses
"__kprobes" attribute.
To solve this, add "notrace" to __kprobes functions
- test_kprobes: clear kprobes between test runs
Clear all kprobes in the test program after running a test set,
because Kunit test can run several times
- fprobe: Fix unregister_fprobe() to wait for RCU grace period
Since the fprobe data structure is removed with hlist_del_rcu(), it
should wait for the RCU grace period. If the caller waits for RCU, we
can use the async variant (e.g. eBPF)
* tag 'probes-fixes-v7.1-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
fprobe: Fix unregister_fprobe() to wait for RCU grace period
test_kprobes: clear kprobes between test runs
kprobes: skip non-symbol addresses in kprobe_add_ksym_blacklist()
Pull to receive:
9a415cc537 ("sched_ext: Avoid UAF in scx_root_enable_workfn() init failure path")
Conflicts with for-7.2's scx_task_iter_relock() rework. The fix moves
put_task_struct(p) past scx_error(); for-7.2 still has it at the old
position. Resolved by dropping the old one.
Signed-off-by: Tejun Heo <tj@kernel.org>
In scx_root_enable_workfn(), put_task_struct(p) is called before scx_error()
dereferences p->comm and p->pid. If the iterator's reference is the last
drop, the task is freed synchronously and the deref becomes a UAF.
Move put_task_struct() past scx_error().
Reported-by: Sashiko <sashiko-bot@kernel.org>
Closes: https://lore.kernel.org/all/20260511214031.AF5E9C2BCB0@smtp.kernel.org/
Fixes: f0e1a0643a ("sched_ext: Implement BPF extensible scheduler class")
Cc: stable@vger.kernel.org # v6.12+
Signed-off-by: Tejun Heo <tj@kernel.org>
Mark !CONFIG_EXT_SUB_SCHED dummy stubs static inline to avoid
-Wunused-function in configs without callers. No functional change.
Signed-off-by: Tejun Heo <tj@kernel.org>
Whether a filesystem's mounts need to undergo a visibility check in user
namespaces is a static property of the filesystem type, not a runtime
property of each superblock instance. Both proc and sysfs always set
SB_I_USERNS_VISIBLE on their superblocks unconditionally (sysfs does so
on first creation, and subsequent mounts reuse the same superblock).
Move this flag from sb->s_iflags (SB_I_USERNS_VISIBLE) to
file_system_type->fs_flags (FS_USERNS_MOUNT_RESTRICTED) so the intent
is expressed at the filesystem type level where it belongs.
All check sites are updated to test sb->s_type->fs_flags instead of
sb->s_iflags. The SB_I_NOEXEC and SB_I_NODEV flags remain on the
superblock as they are runtime properties set during fill_super.
Link: https://patch.msgid.link/72887c5b6204dc3adf5a53104f0be6bd8bc4f6cd.1777278334.git.legion@kernel.org
Reviewed-by: Aleksa Sarai <aleksa@amutable.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
cpuset_can_attach() currently adds the bandwidth of all migrating
SCHED_DEADLINE tasks to sum_migrate_dl_bw. If the source and destination
cpuset effective CPU masks do not overlap, the whole sum is then
reserved in the destination root domain.
set_cpus_allowed_dl(), however, subtracts bandwidth from the source
root domain only when the affinity change really moves the task between
root domains. A DL task can move between cpusets that are still in the
same root domain, so including that task in sum_migrate_dl_bw can reserve
destination bandwidth without a matching source-side subtraction.
Share the root-domain move test with set_cpus_allowed_dl(). Keep
nr_migrate_dl_tasks counting all migrating deadline tasks for cpuset DL
task accounting, but add to sum_migrate_dl_bw only for tasks that need a
root-domain bandwidth move. Keep using the destination cpuset effective
CPU mask and leave the broader can_attach()/attach() transaction model
unchanged.
Fixes: 2ef269ef1a ("cgroup/cpuset: Free DL BW in case can_attach() fails")
Cc: stable@vger.kernel.org # v6.10+
Signed-off-by: Guopeng Zhang <zhangguopeng@kylinos.cn>
Reviewed-by: Waiman Long <longman@redhat.com>
Acked-by: Juri Lelli <juri.lelli@redhat.com>
Tested-by: Juri Lelli <juri.lelli@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
The tryget_task_struct() calls in scx_sub_disable(),
scx_root_enable_workfn() and scx_sub_enable_workfn() can never fail at
the points they're invoked:
- scx_root_enable_workfn() iterates over scx_tasks under scx_tasks_lock
and rq lock. sched_ext_dead() removes tasks from scx_tasks under the
same scx_tasks_lock before put_task_struct_rcu_user() runs in
finish_task_switch(). So any task observed in scx_tasks must have
usage > 0; put_task_struct_rcu_user() hasn't been called and the
delayed_put_task_struct() callback that decrements usage cannot have
been queued.
- scx_sub_disable() and scx_sub_enable_workfn() iterate via
css_task_iter, which takes a reference on each task in
css_task_iter_next() and holds it until the next iter_next() call, so
usage > 0 is guaranteed by the iter itself.
The actual filter for dead tasks is the SCX_TASK_DEAD check inside
scx_task_iter_next_locked(), not tryget; tryget only fails on zero
usage, a state that can't be reached for tasks visible to these iters.
Commit b7d4b28db7 ("sched_ext: Use SCX_TASK_READY test instead of
tryget_task_struct() during class switch") removed an analogous tryget
in the class-switch loop. Convert the remaining tryget calls to plain
get_task_struct() and update the comment in scx_root_enable_workfn()
that suggested tasks could be observed with zero @usage waiting for an
RCU grace period.
Link: https://lore.kernel.org/all/agCLBxHEUqWIepx8@google.com
Suggested-by: Alice Ryhl <aliceryhl@google.com>
Signed-off-by: Andrea Righi <arighi@nvidia.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
The apply_wqattrs_lock()/unlock() helpers were introduced by
commit a0111cf671 ("workqueue: separate out and refactor the locking
of applying attrs") to encapsulate the get_online_cpus() (later
cpus_read_lock()) + mutex_lock(&wq_pool_mutex) acquire pair that was
duplicated across the apply-attrs paths.
Since commit 19af457573 ("workqueue: Remove cpus_read_lock() from
apply_wqattrs_lock()") removed the cpus_read_lock() (pwq creation and
installation now operate on wq_online_cpumask, so CPU hotplug no longer
needs to be excluded), the wrappers have been one-line forwarders to
mutex_lock(&wq_pool_mutex)/mutex_unlock(&wq_pool_mutex).
They no longer encode any non-trivial locking rule and obscure the fact
that callers just take the existing wq_pool_mutex. This align with the
"unnecessary" helpers that got discussed in [1]
Inline the eight call sites and remove the wrappers. No functional
change.
Link: https://lore.kernel.org/all/afs_44-6ToJJVZTn@gmail.com/ [1]
Signed-off-by: Breno Leitao <leitao@debian.org>
Signed-off-by: Tejun Heo <tj@kernel.org>
When an already-exiting task oopses, make_task_dead() currently calls
do_task_dead() with preemption enabled. That is forbidden:
do_task_dead() calls __schedule(), which has a comment saying "WARNING:
must be called with preemption disabled!".
If an oopsing task is preempted in do_task_dead(), between becoming
TASK_DEAD and entering the scheduler explicitly, bad things happen:
finish_task_switch() assumes that once the scheduler has switched away
from a TASK_DEAD task, the task can never run again and its stack is no
longer needed; but that assumption apparently doesn't hold if the dead
task was preempted (the SM_PREEMPT case).
This means that the scheduler ends up repeatedly dropping references on
the dead task's stack, which can lead to use-after-free or double-free
of the entire task stack; in other words, two tasks can end up running
on the same stack, resulting in various kinds of memory corruption.
(This does not just affect "recursively oopsing" tasks; it is enough to
oops once during task exit, for example in a file_operations::release
handler)
Fixes: 7f80a2fd7d ("exit: Stop poorly open coding do_task_dead in make_task_dead")
Cc: stable@kernel.org
Signed-off-by: Jann Horn <jannh@google.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Currently, the BPF instruction set allows bpf-to-bpf calls (or internal
calls, pseudo calls) to use a 32-bit imm field to represent the relative
jump offset.
However, when JIT is disabled or falls back to the interpreter, the
verifier invokes bpf_patch_call_args() to rewrite the call instruction.
In this function, the 32-bit imm is downcast to s16 and stored in the off
field.
void bpf_patch_call_args(struct bpf_insn *insn, u32 stack_depth)
{
stack_depth = max_t(u32, stack_depth, 1);
insn->off = (s16) insn->imm;
insn->imm = interpreters_args[(round_up(stack_depth, 32) / 32) - 1] -
__bpf_call_base_args;
insn->code = BPF_JMP | BPF_CALL_ARGS;
}
If the original imm exceeds the s16 range (i.e., a jump offset greater
than 32767 instructions), this downcast silently truncates the offset,
resulting in an incorrect call target.
Fix this by:
1. In bpf_patch_call_args(), keeping the imm field unchanged and using the
off field to store the index of the interpreter function.
2. In ___bpf_prog_run() for the JMP_CALL_ARGS case, retrieving the
interpreter function pointer from the interpreters_args array using the
off field as the index, and passing the original imm to calculate the
last argument of the interpreter function.
After these changes, the truncation issue is resolved, and __bpf_call_base_args
is also no longer needed and can be removed, which makes the code cleaner.
Performance: In ___bpf_prog_run() for the JMP_CALL_ARGS case, changing the
retrieval of the interpreter function pointer from pointer addition to
direct array indexing improves performance. The possible reason is that the
latter has better instruction-level parallelism. See the v5 discussion [1]
for more details.
[1] https://lore.kernel.org/bpf/f120c3c4-6999-414a-b514-518bb64b4758@zju.edu.cn/
To avoid requiring bpftool changes, keep the new imm/off encoding internal
and restore the legacy xlated dump layout in bpf_insn_prepare_dump().
For bpf-to-bpf call offsets that do not fit in s16, export off as 0 instead
of a truncated and misleading value.
Fixes: 1ea47e01ad ("bpf: add support for bpf_call to interpreter")
Fixes: 7105e828c0 ("bpf: allow for correlation of maps and helpers in dump")
Suggested-by: Xu Kuohai <xukuohai@huaweicloud.com>
Suggested-by: Puranjay Mohan <puranjay@kernel.org>
Co-developed-by: Tianci Cao <ziye@zju.edu.cn>
Signed-off-by: Tianci Cao <ziye@zju.edu.cn>
Co-developed-by: Shenghao Yuan <shenghaoyuan0928@163.com>
Signed-off-by: Shenghao Yuan <shenghaoyuan0928@163.com>
Signed-off-by: Yazhou Tang <tangyazhou518@outlook.com>
Link: https://lore.kernel.org/r/20260506094714.419842-3-tangyazhou@zju.edu.cn
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
The interpreters_args array only accommodates stack depths up to
MAX_BPF_STACK (512 bytes). However, do_misc_fixups() may allow a larger
stack depth if JIT is requested.
If JIT compilation later fails and falls back to the interpreter, the
verifier invokes bpf_patch_call_args() with this oversized stack depth.
This causes a load-time out-of-bounds (OOB) read when calculating the
interpreter function pointer index.
Fix this by changing bpf_patch_call_args() to return an int and explicitly
rejecting the JIT fallback (returning -EINVAL) if the stack depth exceeds
MAX_BPF_STACK.
Fixes: 1ea47e01ad ("bpf: add support for bpf_call to interpreter")
Co-developed-by: Tianci Cao <ziye@zju.edu.cn>
Signed-off-by: Tianci Cao <ziye@zju.edu.cn>
Co-developed-by: Shenghao Yuan <shenghaoyuan0928@163.com>
Signed-off-by: Shenghao Yuan <shenghaoyuan0928@163.com>
Signed-off-by: Yazhou Tang <tangyazhou518@outlook.com>
Acked-by: Xu Kuohai <xukuohai@huawei.com>
Link: https://lore.kernel.org/r/20260506094714.419842-2-tangyazhou@zju.edu.cn
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
/proc/irq/<n>/ directory names are built in `char name[10]` buffers
with `sprintf(name, "%u", irq)`.
Ten-digit IRQ numbers already need 11 bytes including the trailing NUL, and
current sparse-IRQ configurations allow interrupt numbers in that range.
Size the temporary name buffer for the current decimal form and switch
to bounded formatting when creating or removing the proc entry.
Signed-off-by: Pengpeng Hou <pengpeng@iscas.ac.cn>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Link: https://patch.msgid.link/20260404101001.1-genirq-proc-pengpeng@iscas.ac.cn
On PREEMPT_RT, non-HARD irq_work runs in per-CPU kthreads via
run_irq_workd(), so irq_work_sync() uses rcuwait() to wait for BUSY==0.
After irq_work_single() clears BUSY via atomic_cmpxchg(), it still
dereferences @work for irq_work_is_hard() and rcuwait_wake_up().
An irq_work_sync() caller on another CPU that enters after BUSY is cleared
can observe BUSY==0 immediately, return, and free the work before those
accesses complete — causing a use-after-free.
Fix this by wrapping run_irq_workd() in guard(rcu)() so that the entire
irq_work_single() execution is within an RCU read-side critical
section. Then add synchronize_rcu() in irq_work_sync() after
rcuwait_wait_event() to ensure the caller waits for the RCU grace period
before returning, preventing premature frees.
Fixes: 810979682c ("irq_work: Allow irq_work_sync() to sleep if irq_work() no IRQ support.")
Suggested-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Suggested-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Jiayuan Chen <jiayuan.chen@linux.dev>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Reviewed-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Link: https://patch.msgid.link/20260330073234.303732-1-jiayuan.chen@linux.dev
Recently handle_percpu_devid_irq() was changed to call
add_interrupt_randomness(). This introduced a potential deadlock when
handle_percpu_devid_irq() is used to handle an NMI, which can be
detected with lockdep, e.g.
================================
WARNING: inconsistent lock state
7.1.0-rc2-pnmi #465 Not tainted
--------------------------------
inconsistent {INITIAL USE} -> {IN-NMI} usage.
perf/695 [HC1[1]:SC0[0]:HE0:SE1] takes:
ffff00837dfd3a18 (&base->lock){-.-.}-{2:2}, at: lock_timer_base+0x6c/0xac
{INITIAL USE} state was registered at:
_raw_spin_lock_irqsave+0x68/0xb0
lock_timer_base+0x6c/0xac
__mod_timer+0x100/0x32c
add_timer_global+0x2c/0x40
__queue_delayed_work+0xf0/0x140
queue_delayed_work_on+0x134/0x138
mem_cgroup_css_online+0x30c/0x310
online_css+0x34/0x10c
cgroup_init_subsys+0x158/0x1c8
cgroup_init+0x440/0x524
start_kernel+0x888/0x998
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0
----
lock(&base->lock);
<Interrupt>
lock(&base->lock);
*** DEADLOCK ***
Call trace:
_raw_spin_lock_irqsave+0x68/0xb0
lock_timer_base+0x6c/0xac
add_timer_on+0x78/0x16c
add_interrupt_randomness+0x124/0x134
handle_percpu_devid_irq+0xd4/0x16c
handle_irq_desc+0x40/0x58
generic_handle_domain_nmi+0x28/0x50
__gic_handle_nmi.isra.0+0x4c/0xa0
gic_handle_irq+0x38/0x2bc
call_on_irq_stack+0x30/0x48
do_interrupt_handler+0x80/0x98
el1_interrupt+0x90/0xac
el1h_64_irq_handler+0x18/0x24
el1h_64_irq+0x80/0x84
[...]
During review, Thomas pointed out it wouldn't be safe for
handle_percpu_devid_irq() to call add_interrupt_randomness() if it was
used to handle NMIs:
https://lore.kernel.org/lkml/87bjgik042.ffs@tglx/
... but evidently people missed that handle_percpu_devid_irq() *is* used
for NMIs.
While it might seem that NMIs should be handled with a separate
handle_percpu_devid_nmi() function, for various structural reasons this was
impractical, and handle_percpu_devid_irq() has been expected to be used for
NMIs since commits:
21bbbc50f3 ("irqchip/gic-v3: Switch high priority PPIs over to handle_percpu_devid_irq()")
5ff78c8de9 ("genirq: Kill handle_percpu_devid_fasteoi_nmi()")
Taking the above into account, avoid the deadlock by not calling
add_interrupt_randomness() when handle_percpu_devid_irq() is called in an
NMI context. This is consistent with other NNI handling flows, which do not
call add_interrupt_randomness().
At the same time, update the kernel-doc comment to make it clear that
handle_percpu_devid_irq() can be called in NMI context. The rest of
handle_percpu_devid_irq() is currently NMI safe and doesn't need to change.
Fixes: fd7400cfcb ("genirq/chip: Invoke add_interrupt_randomness() in handle_percpu_devid_irq()")
Reported-by: Ada Couprie Diaz <ada.coupriediaz@arm.com>
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Reviewed-by: Jinjie Ruan <ruanjinjie@huawei.com>
Reviewed-by: Marc Zyngier <maz@kernel.org>
Link: https://patch.msgid.link/20260507110518.3128248-1-mark.rutland@arm.com
Commit 4346ba1604 ("fprobe: Rewrite fprobe on function-graph tracer")
changed fprobe to register struct fprobe to an rcu-hlist, but it forgot
to wait for RCU GP. Thus there can be use-after-free if the fprobe is
released right after unregistering. This can be happened on fprobe
event and sample module code.
To fix this issue, add synchronize_rcu() in unregister_fprobe().
Note that BPF is OK because fprobe is used as a part of
bpf_kprobe_multi_link. This unregisters its fprobe in
bpf_kprobe_multi_link_release() and it is deallocated via
bpf_kprobe_multi_link_dealloc(), which is invoked from
bpf_link_defer_dealloc_rcu_gp() RCU callback.
For BPF, this also introduced unregister_fprobe_async() which does
NOT wait for RCU grace priod.
Link: https://lore.kernel.org/all/177813998919.256460.2809243930741138224.stgit@mhiramat.tok.corp.google.com/
Fixes: 4346ba1604 ("fprobe: Rewrite fprobe on function-graph tracer")
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Cgroup v2 doesn't have the concept of memory hardwall, only top_cpuset
has CS_MEM_EXCLUSIVE/CS_MEM_HARDWALL flags, nearest_hardwall_ancestor
always returns top_cpuset with all nodes set, so no need to acquire
callback_lock and scan up cpuset.
Suggested-by: Michal Koutný <mkoutny@suse.com>
Signed-off-by: Chen Wandun <chenwandun@lixiang.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Pull to receive dde2f938d0 ("cgroup/cpuset: move PF_EXITING check
before __GFP_HARDWALL in cpuset_current_node_allowed()") as a
dependency for an upcoming patch in the same function.
Signed-off-by: Tejun Heo <tj@kernel.org>
scx_alloc_and_add_sched() can fail after @sch has been assigned to
ops->priv. In those cases @sch is torn down (either via kfree() through
the err_free_* chain or via kobject_put() -> scx_kobj_release() -> RCU
work), but @ops->priv is left pointing at the about-to-be-freed pointer.
With the recent -EBUSY gate in scx_root_enable_workfn() and
scx_sub_enable_workfn() that rejects an attach when @ops->priv is still
non-NULL, see commit bbf30b383c ("sched_ext: Fix ops->priv clobber on
concurrent attach/detach"), a dangling @ops->priv permanently locks the
kdata out: every future attach attempt sees a stale binding and returns
-EBUSY even though no scheduler is actually attached.
Clear @ops->priv on the post-assign failure paths so that the kdata
returns to its pre-attach state when the function returns ERR_PTR().
Fixes: bbf30b383c ("sched_ext: Fix ops->priv clobber on concurrent attach/detach")
Suggested-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrea Righi <arighi@nvidia.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
cpuset_can_attach() accumulates temporary SCHED_DEADLINE migration
state in the destination cpuset while walking the taskset.
If a later task_can_attach() or security_task_setscheduler() check
fails, cgroup_migrate_execute() treats cpuset as the failing subsystem
and does not call cpuset_cancel_attach() for it. The partially
accumulated state is then left behind and can be consumed by a later
attach, corrupting cpuset DL task accounting and pending DL bandwidth
accounting.
Reset the pending DL migration state from the common error exit when
ret is non-zero. Successful can_attach() keeps the state for
cpuset_attach() or cpuset_cancel_attach().
Fixes: 2ef269ef1a ("cgroup/cpuset: Free DL BW in case can_attach() fails")
Cc: stable@vger.kernel.org # v6.10+
Signed-off-by: Guopeng Zhang <zhangguopeng@kylinos.cn>
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Chen Ridong <chenridong@huaweicloud.com>
Reviewed-by: Waiman Long <longman@redhat.com>
Under heavy concurrent attach/detach operations, scx_claim_exit() can
trigger a NULL pointer dereference. This can be reproduced running the
reload_loop kselftests inside a virtme-ng session:
$ vng -v -- ./tools/testing/selftests/sched_ext/runner -t reload_loop
...
BUG: kernel NULL pointer dereference, address: 0000000000000400
RIP: 0010:scx_claim_exit+0x3b/0x120
Call Trace:
<TASK>
bpf_scx_unreg+0x45/0xb0
bpf_struct_ops_map_link_dealloc+0x39/0x50
bpf_link_release+0x18/0x20
__fput+0x10b/0x2e0
__x64_sys_close+0x47/0xa0
The underlying race (diagnosed by Tejun Heo) is a stomp of @ops->priv,
not a missing NULL check:
T2 unreg(K) T1 reg(K)
----------- ---------
sch = ops->priv = sch_b800
scx_disable; flush_disable_work
[scx_root_disable: scx_root=NULL,
mutex_unlock, state=DISABLED]
mutex_lock; state ok
scx_alloc_and_add_sched:
ops->priv = sch_a800
scx_root = sch_a800; init=0
state=ENABLED; mutex_unlock
[flush returns]
RCU_INIT_POINTER(ops->priv, NULL) <-- clobbers sch_a800
kobject_put(sch_b800)
T1 acquires scx_enable_mutex inside scx_root_disable()'s mutex_unlock
window and starts a fresh attach on the same kdata, assigning sch_a800
to @ops->priv. T2 then continues out of scx_disable()/flush_disable_work
and clobbers @ops->priv to NULL, leaking sch_a800; the bpf_link is gone
but state stays SCX_ENABLED, so all future attaches fail with -EBUSY
permanently. The next bpf_scx_unreg() on that kdata then reads NULL
@ops->priv and dereferences it in scx_claim_exit().
Make @ops->priv the lifecycle binding: in scx_root_enable_workfn() and
scx_sub_enable_workfn(), after the existing state check and still under
scx_enable_mutex, refuse with -EBUSY if @ops->priv is non-NULL. This
rejects an attempt to reuse a kdata that is still bound to a previous
scheduler instance, closing the race without changing the unreg side.
Fixes: 105dcd005b ("sched_ext: Introduce scx_prog_sched()")
Suggested-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrea Righi <arighi@nvidia.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
get_cg_pool_unlocked() handles allocation failures under dmemcg_lock by
dropping the lock, preallocating a pool with GFP_KERNEL, and retrying the
locked lookup and creation path.
If the fallback allocation fails too, pool remains NULL. Since the loop
condition is while (!pool), the function can keep retrying instead of
propagating the allocation failure to the caller.
Set pool to ERR_PTR(-ENOMEM) when the fallback allocation fails so the
loop exits through the existing common return path. The callers already
handle ERR_PTR() from get_cg_pool_unlocked(), so this restores the
expected error path.
Fixes: b168ed458d ("kernel/cgroup: Add "dmem" memory accounting cgroup")
Cc: stable@vger.kernel.org # v6.14+
Signed-off-by: Guopeng Zhang <zhangguopeng@kylinos.cn>
Signed-off-by: Tejun Heo <tj@kernel.org>
Conflict between:
[1] 41e3312861 ("sched_ext: add p->scx.tid and SCX_OPS_TID_TO_TASK lookup")
[2] c941d7391f ("sched_ext: Close root-enable vs sched_ext_dead() race with SCX_TASK_INIT_BEGIN")
in scx_root_enable_workfn()'s post-init block. [1] added a tid hash
insertion under a scoped_guard() for scx_tasks_lock; [2] wraps the same
region in task_rq_lock() for a DEAD recheck. A naive merge would invert the
iter's outer/inner order.
[3] f25ad1e3cb ("sched_ext: Add scx_task_iter_relock() and use it in scx_root_enable_workfn()")
was added to for-7.2 for a clean resolution: scx_task_iter_relock(iter, p)
takes both scx_tasks_lock and @p's rq lock in iter order.
Resolved by routing both sides through [3]'s dual-lock helper: the post-init
region runs under a single scx_task_iter_relock() acquisition, with [2]'s
state machine and [1]'s hash insert in sequence inside it.
Signed-off-by: Tejun Heo <tj@kernel.org>
scx_root_enable_workfn()'s post-init block re-acquires scx_tasks_lock
briefly via a scoped_guard() for the tid hash insertion. c941d7391f
("sched_ext: Close root-enable vs sched_ext_dead() race with
SCX_TASK_INIT_BEGIN") on for-7.1-fixes adds a post-init DEAD recheck that
holds the task's rq lock across the state-machine updates in the same
region. A naive merge would acquire scx_tasks_lock while the rq lock is
held, inverting the iter's outer/inner order (scx_tasks_lock then rq lock).
Add scx_task_iter_relock(iter, p), the counterpart to
scx_task_iter_unlock(), that re-acquires scx_tasks_lock and, if @p is
non-NULL, @p's rq lock. The locks are tracked in @iter so subsequent
iteration releases them.
Use it in scx_root_enable_workfn()'s post-init block and drop the
now-redundant scoped_guard on the hash insertion. The post-init region now
runs with both scx_tasks_lock and the task's rq lock held across the init
failure check, the state-machine updates and the hash insert.
v2: Move scx_task_iter_relock() earlier to ease the for-7.1-fixes merge.
Signed-off-by: Tejun Heo <tj@kernel.org>
scx_fail_parent() leaves cgroup tasks at (state=NONE, sched=parent,
sched_class=ext) until the parent itself is torn down by the scx_error() it
raised. When the later root_disable iterates them, two paths trip on NONE.
scx_disable_and_exit_task() re-enters the wrapper at NONE: the inner switch
returns early but the trailing scx_set_task_sched(p, NULL) clobbers the
parent sched left by scx_fail_parent(), and scx_set_task_state(p, NONE)
wastes a write on an already-NONE task. switched_from_scx() then calls
scx_disable_task(), which WARNs on non-ENABLED state and writes state=READY,
producing a NONE -> READY transition the validation matrix rejects.
Treat NONE as "nothing to do" in both paths. Add a NONE early-return at the
top of scx_disable_and_exit_task() and a parallel NONE check in
switched_from_scx() next to task_dead_and_done().
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Andrea Righi <arighi@nvidia.com>
scx_sub_enable_workfn()'s init pass and scx_sub_disable() migration both
drop the rq lock to call __scx_init_task() against the other sched. A
TASK_DEAD @p can fall through sched_ext_dead() in that window.
sched_ext_dead() runs ops.exit_task() on the sched @p was attached to, not
on the sched whose init just completed, so the new allocation leaks.
Reuse the DEAD signal set by sched_ext_dead(). After __scx_init_task()
returns, take task_rq_lock(p) and check for DEAD; on hit, call
scx_sub_init_cancel_task() against the sub sched the init ran for and drop
@p; on miss, proceed as before.
Reported-by: zhidao su <suzhidao@xiaomi.com>
Link: https://lore.kernel.org/all/20260429133155.3825247-1-suzhidao@xiaomi.com/
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Andrea Righi <arighi@nvidia.com>
scx_root_enable_workfn() drops the iter rq lock for ops.init_task() and a
TASK_DEAD @p can fall through sched_ext_dead() in that window. The race hits
when sched_ext_dead() observes SCX_TASK_INIT (the intermediate state before
@p->scx.sched is published) and dereferences NULL via SCX_HAS_OP(NULL,
exit_task), or observes SCX_TASK_NONE during the unlocked init window and
skips cleanup so exit_task() never runs.
Add SCX_TASK_INIT_BEGIN. The enable path writes NONE -> INIT_BEGIN under the
iter rq lock, then takes the rq lock again after init to walk INIT_BEGIN ->
INIT -> READY. sched_ext_dead() that wins the rq-lock race observes
INIT_BEGIN and sets DEAD without calling into ops; the post-init recheck
unwinds via scx_sub_init_cancel_task().
scx_fork() runs single-threaded against sched_ext_dead() (the task is not on
scx_tasks until scx_post_fork() adds it) so its INIT_BEGIN -> INIT walk
needs no rq-lock pairing; it rolls back to NONE on ops.init_task() failure.
The validation matrix grows the INIT_BEGIN row and the INIT_BEGIN -> DEAD
edge; INIT now requires INIT_BEGIN as the predecessor. scx_sub_disable()'s
migration writes INIT_BEGIN as a synthetic predecessor to satisfy the
tightened verification.
The sub-sched paths still race with sched_ext_dead() during the unlocked
init window. This will be fixed by the next patch.
Reported-by: zhidao su <suzhidao@xiaomi.com>
Link: https://lore.kernel.org/all/20260429133155.3825247-1-suzhidao@xiaomi.com/
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Andrea Righi <arighi@nvidia.com>
SCX_TASK_OFF_TASKS marked tasks already through sched_ext_dead() so cgroup
task iteration would skip them. This can be expressed better with a task
state. Replace the flag with SCX_TASK_DEAD.
scx_disable_and_exit_task() resets state to NONE on its way out, so
sched_ext_dead() now sets DEAD after the wrapper returns. The validation
matrix grows NONE -> DEAD, warns on DEAD -> NONE, and tightens READY's
predecessor to INIT or ENABLED so the new DEAD value cannot silently
transition to READY.
Prepares for the following enable vs dead race fix.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Andrea Righi <arighi@nvidia.com>
Prepare for the SCX_TASK_INIT_BEGIN/DEAD work that follows by collapsing the
scx_init_task() helper. Move the SCX_TASK_RESET_RUNNABLE_AT setting into
scx_set_task_state() on the INIT transition (it was set unconditionally at
every INIT site through the scx_init_task() helper), inline scx_init_task()
into scx_fork() and scx_root_enable_workfn(), and drop the helper.
As a side effect, scx_sub_disable() migration sequence now also sets
RESET_RUNNABLE_AT (it previously wrote INIT directly without going through
scx_init_task()). The flag triggers a runnable_at reset on the next
set_task_runnable(), which is harmless on a task that has just been moved
between scheds.
On root-enable, p->scx.flags is written without the task's rq lock. The task
isn't visible to scx yet, and a follow-up patch restores the lock-held
write.
v2: Note p->scx.flags rq-lock relaxation on root-enable path. (Andrea)
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Andrea Righi <arighi@nvidia.com>
Cleanups in preparation for the state-machine work that follows:
- Convert three sub-sched call sites that open-code
rcu_assign_pointer(p->scx.sched, ...) to scx_set_task_sched().
- Move scx_get_task_state()/scx_set_task_state() above the SCX task iter
section so scx_task_iter_next_locked() can use them without a forward
declaration.
No functional change.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Andrea Righi <arighi@nvidia.com>
BPF_MAP_TYPE_ARENA accepts BPF_PSEUDO_MAP_VALUE offsets at exactly
the end of the arena mapping (off == arena_size). The boundary check
in arena_map_direct_value_addr() uses `>` instead of `>=`, which
incorrectly allows a one-past-end pointer to be accepted.
Change the condition to `>=` to correctly reject offsets that fall
outside the valid arena user_vm range.
Fixes: 317460317a ("bpf: Introduce bpf_arena.")
Signed-off-by: Junyoung Jang <graypanda.inzag@gmail.com>
Reviewed-by: Emil Tsalapatis <emil@etsalapatis.com>
Link: https://lore.kernel.org/r/20260426172505.1947915-1-graypanda.inzag@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Because subprog 0, the main subprog, is considered a global function,
we end up running the arg-tracking dataflow analysis twice on it. That
results in slightly longer verification but mostly in more verbose
verifier logs. This patch fixes it by keeping only the iteration over
global subprogs.
When running over all of Cilium's programs with BPF_LOG_LEVEL2, this
reduces verbosity by ~20% on average.
Fixes: bf0c571f7f ("bpf: introduce forward arg-tracking dataflow analysis")
Signed-off-by: Paul Chaignon <paul.chaignon@gmail.com>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/e4d7b53d4963ef520541a782f5fc8108a168877c.1778176504.git.paul.chaignon@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
ca1d48a86f ("sched_ext: Use offsetofend on both sides of the ops_cid
layout assert") replaced sizeof() with offsetofend() to dodge 32-bit
PPC trailing padding, but the resulting check is tautological: with
CID_OFFSET_MATCH(priv, priv) already enforcing offsetof(priv) equality
and @priv being the same type in both structs, the two offsetofends
are equal by construction. The original protection - catching a stray
field added past @priv in sched_ext_ops_cid - is gone.
Anchor on a zero-size __end[] marker appended after @priv. Its offset
sits flush after @priv regardless of trailing struct padding; if a
field is inserted past @priv, __end shifts and the assert fires.
Closes: https://lore.kernel.org/all/20260508215211.0C03AC2BCB0@smtp.kernel.org/
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Emil Tsalapatis <emil@etsalapatis.com>
- Fix spurious failures in rseq self-tests (Mark Brown)
- Fix rseq rseq::cpu_id_start ABI regression due to
TCMalloc's creative use of the supposedly read-only field.
The fix is to introduce a new ABI variant based on
a new (larger) rseq area registration size, to keep
the TCMalloc use of rseq backwards compatible on new kernels.
(Thomas Gleixner)
- Fix wakeup_preempt_fair() for not waking up task (Vincent Guittot)
- Fix s64 mult overflow in vruntime_eligible() (Zhan Xusheng)
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'sched-urgent-2026-05-09' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler fixes from Ingo Molnar:
- Fix spurious failures in rseq self-tests (Mark Brown)
- Fix rseq rseq::cpu_id_start ABI regression due to TCMalloc's creative
use of the supposedly read-only field
The fix is to introduce a new ABI variant based on a new (larger)
rseq area registration size, to keep the TCMalloc use of rseq
backwards compatible on new kernels (Thomas Gleixner)
- Fix wakeup_preempt_fair() for not waking up task (Vincent Guittot)
- Fix s64 mult overflow in vruntime_eligible() (Zhan Xusheng)
* tag 'sched-urgent-2026-05-09' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
sched/fair: Fix wakeup_preempt_fair() for not waking up task
sched/fair: Fix overflow in vruntime_eligible()
selftests/rseq: Expand for optimized RSEQ ABI v2
rseq: Reenable performance optimizations conditionally
rseq: Implement read only ABI enforcement for optimized RSEQ V2 mode
selftests/rseq: Validate legacy behavior
selftests/rseq: Make registration flexible for legacy and optimized mode
selftests/rseq: Skip tests if time slice extensions are not available
rseq: Revert to historical performance killing behaviour
rseq: Don't advertise time slice extensions if disabled
rseq: Protect rseq_reset() against interrupts
rseq: Set rseq::cpu_id_start to 0 on unregistration
selftests/rseq: Don't run tests with runner scripts outside of the scripts
The DMA API expects that callers use the same attributes when mapping
and unmapping. Add tracking to verify this and catch mismatches.
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
Reviewed-by: Samiullah Khawaja <skhawaja@google.com>
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Link: https://lore.kernel.org/r/20260501-dma-attrs-debug-v2-6-8dbac75cd501@nvidia.com
There are multiple unmapping flows which didn't provide DMA attributes,
which limited DMA debug code to compare the mapping and unmapping
attributes. Let's fix it.
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
Reviewed-by: Samiullah Khawaja <skhawaja@google.com>
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Link: https://lore.kernel.org/r/20260501-dma-attrs-debug-v2-5-8dbac75cd501@nvidia.com
To enable reliable comparison of DMA attributes between map and
unmap operations, store the attribute value in dma_debug_entry.
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
Reviewed-by: Samiullah Khawaja <skhawaja@google.com>
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Link: https://lore.kernel.org/r/20260501-dma-attrs-debug-v2-4-8dbac75cd501@nvidia.com
debug_dma_alloc_pages() always receives a DMA attribute value of 0,
because dma_alloc_pages() never receives any attributes from its callers.
As preparation for upcoming patches, remove this unused attribute from
the debug routine.
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
Reviewed-by: Samiullah Khawaja <skhawaja@google.com>
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Link: https://lore.kernel.org/r/20260501-dma-attrs-debug-v2-3-8dbac75cd501@nvidia.com
For WQ_UNBOUND workqueues, alloc_and_link_pwqs() allocates wq->cpu_pwq
via alloc_percpu() and then calls apply_workqueue_attrs_locked(). On
failure it returns the error directly, bypassing the enomem: label
which holds the only free_percpu(wq->cpu_pwq) in this function.
The caller's error path kfree()s wq without touching wq->cpu_pwq,
leaking one percpu pointer table (nr_cpu_ids * sizeof(void *) bytes) per
failed call.
If kmemleak is enabled, we can see:
unreferenced object (percpu) 0xc0fffa5b121048 (size 8):
comm "insmod", pid 776, jiffies 4294682844
backtrace (crc 0):
pcpu_alloc_noprof+0x665/0xac0
__alloc_workqueue+0x33f/0xa20
alloc_workqueue_noprof+0x60/0x100
Route the error through the existing enomem: cleanup and any error
before this one.
Cc: stable@kernel.org
Fixes: 636b927eba ("workqueue: Make unbound workqueues to use per-cpu pool_workqueues")
Signed-off-by: Breno Leitao <leitao@debian.org>
Signed-off-by: Tejun Heo <tj@kernel.org>
The caller of __queue_work() owns WORK_STRUCT_PENDING, won via
test_and_set_bit() in queue_work_on()/__queue_delayed_work(). The
state machine documented above __queue_work() requires that owner
to either hand the token to a pwq (insert_work() -> set_work_pwq()),
hand it to a timer, or release it via set_work_pool_and_clear_pending().
try_to_grab_pending() relies on this: when it observes
"PENDING && off-queue" it busy-loops, trusting the current owner to
make progress.
The (__WQ_DESTROYING | __WQ_DRAINING) early-return path violates that
contract. It WARN_ONCE()s and bare-returns, leaving work->data with
PENDING set, WORK_STRUCT_PWQ clear, and work->entry empty.
The path is reachable without explicit API abuse: queue_delayed_work()
arms a timer with PENDING set; if drain_workqueue() runs while the
timer is still pending, delayed_work_timer_fn() -> __queue_work() in
softirq context hits the WARN, current is not a wq worker so
is_chained_work() is false, and the work is silently dropped with
PENDING leaked.
Mirror what clear_pending_if_disabled() already does on its analogous
reject path: unpack the off-queue data and call
set_work_pool_and_clear_pending() to release the token before
returning.
I was able to reproduce this by queueing several slow works on
a max_active=1 wq, arm a delayed_work whose timer fires while
drain_workqueue() is blocked, then call cancel_delayed_work_sync().
Without this patch the cancel livelocks at 100% CPU; with it the cancel
returns immediately.
Signed-off-by: Breno Leitao <leitao@debian.org>
Signed-off-by: Tejun Heo <tj@kernel.org>
sizeof() includes trailing struct pad, offsetofend() doesn't. On
32-bit PPC, sched_ext_ops_cid tail-pads 4 bytes past @priv and the
assert trips. Use offsetofend() on both sides.
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202605081637.DbH4SZ1E-lkp@intel.com/
Fixes: 7e655ed7b9 ("sched_ext: Add bpf_sched_ext_ops_cid struct_ops type")
Signed-off-by: Tejun Heo <tj@kernel.org>
For built with PREEMPT_RT kernels, the scx_disable_irq_workfn() is
called from per-cpu irq_work kthreads context, this means that
when call the scx_dump_state() in the scx_disable_irq_workfn() to
output current->comm/pid, it always output current irq_work kthread's
comm/pid. this commit therefore use the IRQ_WORK_INIT_HARD() to
initialize sch->disable_irq_work to make scx_disable_irq_workfn() is
called from hardirq context.
Fixes: f4a6c506d1 ("sched_ext: Always bounce scx_disable() through irq_work")
Signed-off-by: Zqiang <qiang.zhang@linux.dev>
Signed-off-by: Tejun Heo <tj@kernel.org>
W=1 with CONFIG_EXT_SUB_SCHED=n flags 'err_msg' uninitialized and
'err_free_lb_resched' unused. Initialize err_msg and gate the label.
Signed-off-by: Tejun Heo <tj@kernel.org>
scx_find_sub_sched()'s only caller, scx_bpf_sub_dispatch(), is gated on
CONFIG_EXT_SUB_SCHED. When CONFIG_EXT_SUB_SCHED=n the caller compiles out
and the stub becomes dead code, tripping -Wunused-function on randconfigs.
Drop the stub.
Fixes: 25037af712 ("sched_ext: Add rhashtable lookup for sub-schedulers")
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/all/202605080556.42PXw8U9-lkp@intel.com/
Signed-off-by: Tejun Heo <tj@kernel.org>
Since prepare_alloc_pages() unconditionally adds __GFP_HARDWALL for the
fast path when cpusets are enabled, the __GFP_HARDWALL check in
cpuset_current_node_allowed() causes the PF_EXITING escape path to be
skipped on the first allocation attempt. This makes it unreachable in
the common case, so dying tasks can get stuck in direct reclaim or even
trigger OOM while trying to exit, despite being allowed to allocate from
any node.
Move the PF_EXITING check before __GFP_HARDWALL so that dying tasks
can allocate memory from any node to exit quickly, even when cpusets
are enabled.
Also update the function comment to reflect the actual behavior of
prepare_alloc_pages() and the corrected check ordering.
Signed-off-by: Chen Wandun <chenwandun@lixiang.com>
Acked-by: Michal Koutný <mkoutny@suse.com>
Acked-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
This patch continues the effort to refactor workqueue APIs, which has begun
with the changes introducing new workqueues and a new alloc_workqueue flag:
commit 128ea9f6cc ("workqueue: Add system_percpu_wq and system_dfl_wq")
commit 930c2ea566 ("workqueue: Add new WQ_PERCPU flag")
The point of the refactoring is to eventually alter the default behavior of
workqueues to become unbound by default so that their workload placement is
optimized by the scheduler.
Before that to happen, workqueue users must be converted to the better named
new workqueues with no intended behaviour changes:
system_wq -> system_percpu_wq
system_unbound_wq -> system_dfl_wq
This way the old obsolete workqueues (system_wq, system_unbound_wq) can be
removed in the future.
Cc: Luis Chamberlain <mcgrof@kernel.org>
Link: https://lore.kernel.org/all/20250221112003.1dSuoGyc@linutronix.de/
Suggested-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Marco Crivellari <marco.crivellari@suse.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
scx_link_sched() holds scx_sched_lock. The scx_error() calls inside take the
same lock through scx_claim_exit() and deadlock. Move them out of the guard.
Fixes: 6b4576b097 ("sched_ext: Reject sub-sched attachment to a disabled parent")
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Andrea Righi <arighi@nvidia.com>
Make sure to only call pick_next_entity() on an non-empty cfs_rq.
The assumption that p is always enqueued and not delayed, is only true for
wakeup. If p was moved while delayed, pick_next_entity() will dequeue it and
the cfs might become empty. Test if there are still queued tasks before trying
again to determine if p could be the next one to be picked.
There are at least 2 cases:
When cfs becomes idle, it tries to pull tasks but if those pulled tasks are
delayed, they will be dequeued when attached to cfs. attach_tasks() ->
attach_task() -> wakeup_preempt(rq, p, 0);
A misfit task running on cfs A triggers a load balance to be pulled on a better
cpu, the load balance on cfs B starts an active load balance to pulled the
running misfit task. If there is a delayed dequeue task on cfs A, it can be
pulled instead of the previously running misfit task. attach_one_task() ->
attach_task() -> wakeup_preempt(rq, p, 0);
Fixes: ac8e69e693 ("sched/fair: Fix wakeup_preempt_fair() vs delayed dequeue")
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260503104503.1732682-1-vincent.guittot@linaro.org
Zhan Xusheng reported running into sporadic a s64 mult overflow in
vruntime_eligible().
When constructing a worst case scenario:
If you have cgroups, then you can have an entity of weight 2 (per
calc_group_shares()), and its vlag should then be bounded by: (slice+TICK_NSEC)
* NICE_0_LOAD, which is around 44 bits as per the comment on entity_key().
The other extreme is 100*NICE_0_LOAD, thus you get:
{key, weight}[] := {
puny: { (slice + TICK_NSEC) * NICE_0_LOAD, 2 },
max: { 0, 100*NICE_0_LOAD },
}
The avg_vruntime() would end up being very close to 0 (which is
zero_vruntime), so no real help making that more accurate.
vruntime_eligible(puny) ends up with:
avg = 2 * puny.key (+ 0)
load = 2 + 100 * NICE_0_LOAD
avg >= puny.key * load
And that is: (slice + TICK_NSEC) * NICE_0_LOAD * NICE_0_LOAD * 100, which will
overflow s64.
Zhan suggested using __builtin_mul_overflow(), however after staring at
compiler output for various architectures using godbolt, it seems that using an
__int128 multiplication often results in better code.
Specifically, a number of architectures already compute the __int128 product to
determine the overflow. Eg. arm64 already has the 'smulh' instruction used. By
explicitly doing an __int128 multiply, it will emit the 'mul; smulh' pattern,
which modern cores can fuse (armv8-a clang-22.1.0). x86_64 has less branches
(no OF handling).
Since Linux has ARCH_SUPPORTS_INT128 to gate __int128 usage, also provide the
__builtin_mul_overflow() variant as a fallback.
[peterz: Changelog and __int128 bits]
Fixes: 556146ce5e ("sched/fair: Avoid overflow in enqueue_entity()")
Reported-by: Zhan Xusheng <zhanxusheng1024@gmail.com>
Closes: https://patch.msgid.link/20260415145742.10359-1-zhanxusheng%40xiaomi.com
Signed-off-by: Zhan Xusheng <zhanxusheng@xiaomi.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260505103155.GN3102924%40noisy.programming.kicks-ass.net
Due to the incompatibility with TCMalloc the RSEQ optimizations and
extended features (time slice extensions) have been disabled and made
run-time conditional.
The original RSEQ implementation, which TCMalloc depends on, registers a 32
byte region (ORIG_RSEG_SIZE). This region has a 32 byte alignment
requirement.
The extension safe newer variant exposes the kernel RSEQ feature size via
getauxval(AT_RSEQ_FEATURE_SIZE) and the alignment requirement via
getauxval(AT_RSEQ_ALIGN). The alignment requirement is that the registered
RSEQ region is aligned to the next power of two of the feature size. The
kernel currently has a feature size of 33 bytes, which means the alignment
requirement is 64 bytes.
The TCMalloc RSEQ region is embedded into a cache line aligned data
structure starting at offset 32 bytes so that bytes 28-31 and the
cpu_id_start field at bytes 32-35 form a 64-bit little endian pointer with
the top-most bit (63 set) to check whether the kernel has overwritten
cpu_id_start with an actual CPU id value, which is guaranteed to not have
the top most bit set.
As this is part of their performance tuned magic, it's a pretty safe
assumption, that TCMalloc won't use a larger RSEQ size.
This allows the kernel to declare that registrations with a size greater
than the original size of 32 bytes, which is the cases since time slice
extensions got introduced, as RSEQ ABI v2 with the following differences to
the original behaviour:
1) Unconditional updates of the user read only fields (CPU, node, MMCID)
are removed. Those fields are only updated on registration, task
migration and MMCID changes.
2) Unconditional evaluation of the criticial section pointer is
removed. It's only evaluated when user space was interrupted and was
scheduled out or before delivering a signal in the interrupted
context.
3) The read/only requirement of the ID fields is enforced. When the
kernel detects that userspace manipulated the fields, the process is
terminated. This ensures that multiple entities (libraries) can
utilize RSEQ without interfering.
4) Todays extended RSEQ feature (time slice extensions) and future
extensions are only enabled in the v2 enabled mode.
Registrations with the original size of 32 bytes operate in backwards
compatible legacy mode without performance improvements and extended
features.
Unfortunately that also affects users of older GLIBC versions which
register the original size of 32 bytes and do not evaluate the kernel
required size in the auxiliary vector AT_RSEQ_FEATURE_SIZE.
That's the result of the lack of enforcement in the original implementation
and the unwillingness of a single entity to cooperate with the larger
ecosystem for many years.
Implement the required registration changes by restructuring the spaghetti
code and adding the size/version check. Also add documentation about the
differences of legacy and optimized RSEQ V2 mode.
Thanks to Mathieu for pointing out the ORIG_RSEQ_SIZE constraints!
Fixes: d6200245c7 ("rseq: Allow registering RSEQ with slice extension")
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
Tested-by: Dmitry Vyukov <dvyukov@google.com>
Link: https://patch.msgid.link/20260428224427.927160119%40kernel.org
Cc: stable@vger.kernel.org
The optimized RSEQ V2 mode requires that user space adheres to the ABI
specification and does not modify the read-only fields cpu_id_start,
cpu_id, node_id and mm_cid behind the kernel's back.
While the kernel does not rely on these fields, the adherence to this is a
fundamental prerequisite to allow multiple entities, e.g. libraries, in an
application to utilize the full potential of RSEQ without stepping on each
other toes.
Validate this adherence on every update of these fields. If the kernel
detects that user space modified the fields, the application is force
terminated.
Fixes: d6200245c7 ("rseq: Allow registering RSEQ with slice extension")
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
Tested-by: Dmitry Vyukov <dvyukov@google.com>
Link: https://patch.msgid.link/20260428224427.845230956%40kernel.org
Cc: stable@vger.kernel.org
Remove the unused functions __clocksource_update_freq_hz() and
__clocksource_update_freq_khz().
Then make __clocksource_update_freq_scale() static as it is not used
from external callers anymore. Also clean up the comment accordingly.
Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Acked-by: John Stultz <jstultz@google.com>
Link: https://patch.msgid.link/20260504-clocksource-update_freq-v2-1-3e696fb01776@linutronix.de
alarm_handle_timer() was converted from returning enum alarmtimer_restart
to void, but the kernel-doc "Return:" line was not removed. Remove the
stale description.
Fixes: 2634303f87 ("alarmtimers: Remove return value from alarm functions")
Signed-off-by: Zhan Xusheng <zhanxusheng@xiaomi.com>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Link: https://patch.msgid.link/20260429080635.166790-1-zhanxusheng@xiaomi.com
Systems with heterogeneous CPU capacities, such as big.LITTLE, have
reported power issues since the introduction of the new timer migration
code.
Timers migrate from small capacity CPUs to big ones, degrading their
target residency and thus overall power consumption.
Solve this with splitting hierarchies per CPU capacity. For example in
a big.LITTLE machine, split a single hierarchy in two: one for big
capacity CPUs and another one for small capacity CPUs. This way global
timers only migrate across CPUs of the same capacity.
For simplicity purpose, split hierarchies keep the same number of
possible levels as if there were a single hierarchy, even though the
CPUs are distributed between multiple hierarchies. This could be a
problem on NUMA systems with heterogeneous CPU capacities (provided that
ever exists yet) where useless intermediate nodes may be created.
Solving this properly will imply on boot to know in advance how many
capacities are available and the number of CPUs for each of them.
Reported-by: Sehee Jeong <sehee1.jeong@samsung.com>
Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Link: https://patch.msgid.link/20260423165354.95152-5-frederic@kernel.org
When a new root is created, the old root is connected to it and
propagates up its own assumed to be active state, since the hotplug
control CPU is itself active and part of the old root.
However with per-capacity hierarchies, this assumption won't be true
anymore because the hotplug control CPU calling the timer migration
prepare callback may not belong to the same hierarchy as the booting
CPU.
To solve this, track the available CPUs per hierarchies so that the
root connection can be offlined to safe CPUs.
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Link: https://patch.msgid.link/20260423165354.95152-4-frederic@kernel.org
In order to prepare for separating out CPUs from different capacities in
distinct hierarchies, create a hierarchy structure that group setup
must rely upon.
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Link: https://patch.msgid.link/20260423165354.95152-3-frederic@kernel.org
The hotplug control CPU is assumed to be active in the hierarchy but
that doesn't imply that the root is active. If the current CPU is not
the one that activated the current hierarchy, and the CPU performing
this duty is still halfway through the tree, the root may still be
observed inactive. And this can break the activation of a new root as in
the following scenario:
1) Initially, the whole system has 64 CPUs and only CPU 63 is awake.
[GRP1:0]
active
/ | \
/ | \
[GRP0:0] [...] [GRP0:7]
idle idle active
/ | \ |
CPU 0 CPU 1 ... CPU 63
idle idle active
2) CPU 63 goes idle _but_ due to a #VMEXIT it hasn't yet reached the
[GRP1:0]->parent dereference (that would be NULL and stop the walk)
in __walk_groups_from().
[GRP1:0]
idle
/ | \
/ | \
[GRP0:0] [...] [GRP0:7]
idle idle idle
/ | \ |
CPU 0 CPU 1 ... CPU 63
idle idle idle
3) CPU 1 wakes up, activates GRP0:0 but didn't yet manage to propagate
up to GRP1:0 due to yet another #VMEXIT.
[GRP1:0]
idle
/ | \
/ | \
[GRP0:0] [...] [GRP0:7]
active idle idle
/ | \ |
CPU 0 CPU 1 ... CPU 63
idle active idle
3) CPU 0 wakes up and doesn't need to walk above GRP0:0 as it's CPU 1
role.
[GRP1:0]
idle
/ | \
/ | \
[GRP0:0] [...] [GRP0:7]
active idle idle
/ | \ |
CPU 0 CPU 1 ... CPU 63
active active idle
4) CPU 0 boots CPU 64. It creates a new root for it.
[GRP2:0]
idle
/ \
/ \
[GRP1:0] [GRP1:1]
idle idle
/ | \ \
/ | \ \
[GRP0:0] [...] [GRP0:7] [GRP0:8]
active idle idle idle
/ | \ | |
CPU 0 CPU 1 ... CPU 63 CPU 64
active active idle offline
5) CPU 0 activates the new root, but note that GRP1:0 is still idle,
waiting for CPU 1 to resume from #VMEXIT and activate it.
[GRP2:0]
active
/ \
/ \
[GRP1:0] [GRP1:1]
idle idle
/ | \ \
/ | \ \
[GRP0:0] [...] [GRP0:7] [GRP0:8]
active idle idle idle
/ | \ | |
CPU 0 CPU 1 ... CPU 63 CPU 64
active active idle offline
6) CPU 63 resumes after #VMEXIT and sees the new GRP1:0 parent.
Therefore it propagates the stale inactive state of GRP1:0 up to
GRP2:0.
[GRP2:0]
idle
/ \
/ \
[GRP1:0] [GRP1:1]
idle idle
/ | \ \
/ | \ \
[GRP0:0] [...] [GRP0:7] [GRP0:8]
active idle idle idle
/ | \ | |
CPU 0 CPU 1 ... CPU 63 CPU 64
active active idle offline
7) CPU 1 resumes after #VMEXIT and finally activates GRP1:0. But it
doesn't observe its parent link because no ordering enforced that.
Therefore GRP2:0 is spuriously left idle.
[GRP2:0]
idle
/ \
/ \
[GRP1:0] [GRP1:1]
active idle
/ | \ \
/ | \ \
[GRP0:0] [...] [GRP0:7] [GRP0:8]
active idle idle idle
/ | \ | |
CPU 0 CPU 1 ... CPU 63 CPU 64
active active idle offline
Such races are highly theoretical and the problem would solve itself
once the old root ever becomes idle again. But it still leaves a taste
of discomfort.
Fix it with enforcing a fully ordered atomic read of the old root state
before propagating the activate state up to the new root. It has a two
directions ordering effect:
* Acquire + release of the latest old root state: If the hotplug control
CPU is not the one that woke up the old root, make sure to acquire its
active state and propagate it upwards through the ordered chain of
activation (the acquire pairs with the cmpxchg() in tmigr_active_up()
and subsequent releases will pair with atomic_read_acquire() and
smp_mb__after_atomic() in tmigr_inactive_up()).
* Release: If the hotplug control CPU is not the one that must wake up
the old root, but the CPU covering that is lagging behind its duty,
publish the links from the old root to the new parents. This way the
lagging CPU will propagate the active state itself.
Fixes: 7ee9887703 ("timers: Implement the hierarchical pull model")
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Link: https://patch.msgid.link/20260423165354.95152-2-frederic@kernel.org
- Fix devm_alloc_workqueue() passing a va_list as a positional arg to the
variadic alloc_workqueue() macro, which garbled wq->name and skipped
lockdep init on the devm path. Fold both noprof entry points onto a
va_list helper. Also, annotate __printf(1, 0).
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Merge tag 'wq-for-7.1-rc2-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq
Pull workqueue fixes from Tejun Heo:
- Fix devm_alloc_workqueue() passing a va_list as a positional arg to
the variadic alloc_workqueue() macro, which garbled wq->name and
skipped lockdep init on the devm path. Fold both noprof entry points
onto a va_list helper.
Also, annotate it using __printf(1, 0)
* tag 'wq-for-7.1-rc2-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq:
workqueue: Annotate alloc_workqueue_va() with __printf(1, 0)
workqueue: fix devm_alloc_workqueue() va_list misuse
- During v6.19, cgroup task unlink was moved from do_exit() to after the
final task switch to satisfy a controller invariant. That left the kernel
seeing tasks past exit_signals() longer than userspace expected, and
several v7.0 follow-ups tried to bridge the gap by making rmdir wait for
the kernel side. None held up. The latest is an A-A deadlock when rmdir
is invoked by the reaper of zombies whose pidns teardown the rmdir itself
is waiting on, which points at the synchronizing approach being
fundamentally wrong:
- Take a different approach: drop the wait, leave rmdir's user-visible
side returning as soon as cgroup.procs is empty, and defer the css
percpu_ref kill that drives ->css_offline() until the cgroup is fully
depopulated.
- Tagged for stable. Somewhat invasive but contained. The hope is that
fixing forward sticks. If not, the fallback is to revert the entire
chain and rework on the development branch.
- Doesn't plug a pre-existing analogous race in
cgroup_apply_control_disable() (controller disable via subtree_control).
Not a regression. The development branch will do the more invasive
restructuring needed for that.
- Documentation update for cgroup-v1 charge-commit section that still
referenced functions removed when the memcg hugetlb try-commit-cancel
protocol was retired.
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Merge tag 'cgroup-for-7.1-rc2-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup
Pull cgroup fixes from Tejun Heo:
- During v6.19, cgroup task unlink was moved from do_exit() to after the
final task switch to satisfy a controller invariant. That left the kernel
seeing tasks past exit_signals() longer than userspace expected, and
several v7.0 follow-ups tried to bridge the gap by making rmdir wait for
the kernel side. None held up.
The latest is an A-A deadlock when rmdir is invoked by the reaper of
zombies whose pidns teardown the rmdir itself is waiting on, which
points at the synchronizing approach being fundamentally wrong.
Take a different approach: drop the wait, leave rmdir's user-visible
side returning as soon as cgroup.procs is empty, and defer the css
percpu_ref kill that drives ->css_offline() until the cgroup is fully
depopulated.
Tagged for stable. Somewhat invasive but contained. The hope is that
fixing forward sticks. If not, the fallback is to revert the entire
chain and rework on the development branch.
Note that this doesn't plug a pre-existing analogous race in
cgroup_apply_control_disable() (controller disable via
subtree_control). Not a regression. The development branch will do
the more invasive restructuring needed for that.
- Documentation update for cgroup-v1 charge-commit section that still
referenced functions removed when the memcg hugetlb try-commit-cancel
protocol was retired.
* tag 'cgroup-for-7.1-rc2-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
docs: cgroup-v1: Update charge-commit section
cgroup: Defer css percpu_ref kill on rmdir until cgroup is depopulated
- Fix idle CPU selection returning prev_cpu outside the task's cpus_ptr
when the BPF caller's allowed mask was wider. Stable backport.
- Two opposite-direction gaps in scx_task_iter's cgroup-scoped mode
versus the global mode:
- Tasks past exit_signals() are filtered by the cgroup walk but kept by
global. Sub-scheduler enable abort leaked __scx_init_task() state.
Add a CSS_TASK_ITER_WITH_DEAD flag to cgroup's task iterator
(scx_task_iter is its only user) and use it.
- Tasks past sched_ext_dead() are still returned, tripping
WARN_ON_ONCE() in callers or making them touch torn-down state. Mark
and skip under the per-task rq lock.
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Merge tag 'sched_ext-for-7.1-rc2-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/sched_ext
Pull sched_ext fixes from Tejun Heo:
- Fix idle CPU selection returning prev_cpu outside the task's cpus_ptr
when the BPF caller's allowed mask was wider. Stable backport.
- Two opposite-direction gaps in scx_task_iter's cgroup-scoped mode
versus the global mode:
- Tasks past exit_signals() are filtered by the cgroup walk but kept
by global. Sub-scheduler enable abort leaked __scx_init_task()
state. Add a CSS_TASK_ITER_WITH_DEAD flag to cgroup's task
iterator (scx_task_iter is its only user) and use it.
- Tasks past sched_ext_dead() are still returned, tripping
WARN_ON_ONCE() in callers or making them touch torn-down state.
Mark and skip under the per-task rq lock.
* tag 'sched_ext-for-7.1-rc2-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/sched_ext:
sched_ext: idle: Recheck prev_cpu after narrowing allowed mask
sched_ext: Skip past-sched_ext_dead() tasks in scx_task_iter_next_locked()
cgroup, sched_ext: Include exiting tasks in cgroup iter
The recent RSEQ optimization work broke the TCMalloc abuse of the RSEQ ABI
as it not longer unconditionally updates the CPU, node, mm_cid fields,
which are documented as read only for user space. Due to the observed
behavior of the kernel it was possible for TCMalloc to overwrite the
cpu_id_start field for their own purposes and rely on the kernel to update
it unconditionally after each context switch and before signal delivery.
The RSEQ ABI only guarantees that these fields are updated when the data
changes, i.e. the task is migrated or the MMCID of the task changes due to
switching from or to per CPU ownership mode.
The optimization work eliminated the unconditional updates and reduced them
to the documented ABI guarantees, which results in a massive performance
win for syscall, scheduling heavy work loads, which in turn breaks the
TCMalloc expectations.
There have been several options discussed to restore the TCMalloc
functionality while preserving the optimization benefits. They all end up
in a series of hard to maintain workarounds, which in the worst case
introduce overhead for everyone, e.g. in the scheduler.
The requirements of TCMalloc and the optimization work are diametral and
the required work arounds are a maintainence burden. They end up as fragile
constructs, which are blocking further optimization work and are pretty
much guaranteed to cause more subtle issues down the road.
The optimization work heavily depends on the generic entry code, which is
not used by all architectures yet. So the rework preserved the original
mechanism moslty unmodified to keep the support for architectures, which
handle rseq in their own exit to user space loop. That code is currently
optimized out by the compiler on architectures which use the generic entry
code.
This allows to revert back to the original behaviour by replacing the
compile time constant conditions with a runtime condition where required,
which disables the optimization and the dependend time slice extension
feature until the run-time condition can be enabled in the RSEQ
registration code on a per task basis again.
The following changes are required to restore the original behavior, which
makes TCMalloc work again:
1) Replace the compile time constant conditionals with runtime
conditionals where appropriate to prevent the compiler from optimizing
the legacy mode out
2) Enforce unconditional update of IDs on context switch for the
non-optimized v1 mode
3) Enforce update of IDs in the pre signal delivery path for the
non-optimized v1 mode
4) Enforce update of IDs in the membarrier(RSEQ) IPI for the
non-optimized v1 mode
5) Make time slice and future extensions depend on optimized v2 mode
This brings back the full performance problems, but preserves the v2
optimization code and for generic entry code using architectures also the
TIF_RSEQ optimization which avoids a full evaluation of the exit to user
mode loop in many cases.
Fixes: 566d8015f7 ("rseq: Avoid CPU/MM CID updates when no event pending")
Reported-by: Mathias Stearn <mathias@mongodb.com>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
Tested-by: Dmitry Vyukov <dvyukov@google.com>
Closes: https://lore.kernel.org/CAHnCjA25b+nO2n5CeifknSKHssJpPrjnf+dtr7UgzRw4Zgu=oA@mail.gmail.com
Link: https://patch.msgid.link/20260428224427.517051752%40kernel.org
Cc: stable@vger.kernel.org
The wrapper functions __trace_set_current_state() and
__trace_set_need_resched() allow the tracepoints to be called from code
outside sched/core.c, those calls are already guarded by a
tracepoint_enabled(<tp>) so there is no need to repeat this check once
again inside the call using trace_<tp>().
Use the new trace_call__<tp>() API to directly call the tracepoint
without check. Those helper functions must be called after the
appropriate check.
Signed-off-by: Gabriele Monaco <gmonaco@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260429094227.34087-1-gmonaco@redhat.com
Currently, the membarrier system call uses a single global mutex
(`membarrier_ipi_mutex`) to serialize expedited commands. This causes
significant contention on large systems when multiple threads invoke
membarrier concurrently, even if they target different CPUs.
This contention becomes critical when combined with CFS bandwidth
throttling/unthrottling, during which interrupts can be disabled for
relatively long periods on target CPUs. If membarrier is waiting for a
response from such a CPU, it holds the global mutex, blocking all other
membarrier calls on the system. This cascade effect can lead to hard
lockups when thousands of threads stall waiting for the mutex.
Optimize `MEMBARRIER_CMD_PRIVATE_EXPEDITED_RSEQ` when a specific CPU is
targeted by introducing per-CPU mutexes. Broadcast commands and commands
without a specific CPU target continue to use the global mutex.
This prevents the cascade lockup scenario. As measured by the stress test
introduced in the subsequent patch, on an AMD Turin machine with 384 CPUs
(2 NUMA nodes with SMT=2), this optimization yields 200x more
throughput.
Signed-off-by: Aniket Gattani <aniketgattani@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260503212205.3714217-2-aniketgattani@google.com
Ian noted that commit 77de62ad3d ("perf/core: Fix refcount bug and
potential UAF in perf_mmap") would cause a deadlock due to
event->mmap_mutex recursion.
This happens because we're now calling perf_mmap_close() under
mmap_mutex, while that function itself can also take mmap_mutex.
Solve this by noting that perf_mmap_close() is far more complicated
than we need at this particular point, since it deals with scenarios
that cannot happen in this particular case.
Replace the call to perf_mmap_close() with a very narrow undo for the
case of first-exposure. If this is not the first mmap(), there is no
race and it is fine to drop the lock and call perf_mmap_close() to
handle to more complicated scenarios.
Note: move the rb->mmap_user (namespace) handling into the rb
init/free code such that it does not complicate the mmap handling.
Fixes: 77de62ad3d ("perf/core: Fix refcount bug and potential UAF in perf_mmap")
Reported-by: Ian Rogers <irogers@google.com>
Closes: https://patch.msgid.link/CAP-5%3DfVJyVMZw%3DDqP53Kxg58nUmJ_0bxoaeOKAbC03BVc11HaA%40mail.gmail.com
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260326112821.GK3738786@noisy.programming.kicks-ass.net
scx_vexit() forwards (fmt, args) to vscnprintf(); bstr_format() and
__bstr_format() forward fmt to bstr_printf(); the BPF kfunc wrappers
scx_bpf_exit_bstr(), scx_bpf_error_bstr() and scx_bpf_dump_bstr() in
turn forward fmt to those formatters. None of them have __printf(),
so clang -Wmissing-format-attribute fires on the forwarded calls and
C-side callers don't get format-string checking.
Annotate the six functions with __printf(N, 0) matching the fmt
parameter position in each.
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/all/202605041112.Y6OG7v9r-lkp@intel.com/
Signed-off-by: Tejun Heo <tj@kernel.org>
scx_select_cpu_dfl() narrows @allowed to @cpus_allowed & @p->cpus_ptr
when the BPF caller supplies a @cpus_allowed that differs from
@p->cpus_ptr and @p doesn't have full affinity. However,
@is_prev_allowed was computed against the original (wider)
@cpus_allowed, so the prev_cpu fast paths could pick a @prev_cpu that
is in @cpus_allowed but not in @p->cpus_ptr, violating the intended
invariant that the returned CPU is always usable by @p. The kernel
masks this via the SCX_EV_SELECT_CPU_FALLBACK fallback, but the
behavior contradicts the documented contract.
Move the @is_prev_allowed evaluation past the narrowing block so it
tests against the final @allowed mask.
Fixes: ee9a4e9279 ("sched_ext: idle: Properly handle invalid prev_cpu during idle selection")
Cc: stable@vger.kernel.org # v6.16+
Assisted-by: Claude <noreply@anthropic.com>
Signed-off-by: David Carlier <devnexen@gmail.com>
Reviewed-by: Andrea Righi <arighi@nvidia.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
sysrq_handle_sched_ext_reset() is called from __handle_sysrq(), which
already holds rcu_read_lock() while invoking the sysrq handler. Remove
the redundant rcu_read_lock/unlock() pair.
Signed-off-by: Zqiang <qiang.zhang@linux.dev>
Reviewed-by: Cheng-Yang Chou <yphbchou0911@gmail.com>
Reviewed-by: Andrea Righi <arighi@nvidia.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
scx_task_iter's cgroup-scoped mode can return tasks whose
sched_ext_dead() has already completed: cgroup_task_dead() removes
from cset->tasks after sched_ext_dead() in finish_task_switch() and is
irq-work deferred on PREEMPT_RT. The global mode is fine -
sched_ext_dead() removes from scx_tasks via list_del_init() first.
Callers (sub-sched enable prep/abort/apply, scx_sub_disable(),
scx_fail_parent()) assume returned tasks are still on @sch and trip
WARN_ON_ONCE() or operate on torn-down state otherwise.
Set %SCX_TASK_OFF_TASKS in sched_ext_dead() under @p's rq lock and
have scx_task_iter_next_locked() skip flagged tasks under the same
lock. Setter and reader serialize on the per-task rq lock - no race.
Signed-off-by: Tejun Heo <tj@kernel.org>
a72f73c4dd ("cgroup: Don't expose dead tasks in cgroup") made
css_task_iter_advance() skip exiting tasks so cgroup.procs stays consistent
with waitpid() visibility. Unfortunately, this broke scx_task_iter.
scx_task_iter walks either scx_tasks (global) or a cgroup subtree via
css_task_iter() and the two modes are expected to cover the same set of
tasks. After the above change the cgroup-scoped mode silently skips tasks
past exit_signals() that are still on scx_tasks.
scx_sub_enable_workfn()'s abort path is one of the symptoms: an exiting
SCX_TASK_SUB_INIT task can race past the cgroup iter leaking
__scx_init_task() state. Other iterations share the same gap.
Add CSS_TASK_ITER_WITH_DEAD to opt out of the skip and use it from
scx_task_iter().
Fixes: b0e4c2f8a0 ("sched_ext: Implement cgroup subtree iteration for scx_task_iter")
Reported-by: Cheng-Yang Chou <yphbchou0911@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
A chain of commits going back to v7.0 reworked rmdir to satisfy the
controller invariant that a subsystem's ->css_offline() must not run while
tasks are still doing kernel-side work in the cgroup.
[1] d245698d72 ("cgroup: Defer task cgroup unlink until after the task is done switching out")
[2] a72f73c4dd ("cgroup: Don't expose dead tasks in cgroup")
[3] 1b164b876c ("cgroup: Wait for dying tasks to leave on rmdir")
[4] 4c56a8ac68 ("cgroup: Fix cgroup_drain_dying() testing the wrong condition")
[5] 13e786b64b ("cgroup: Increment nr_dying_subsys_* from rmdir context")
[1] moved task cset unlink from do_exit() to finish_task_switch() so a
task's cset link drops only after the task has fully stopped scheduling.
That made tasks past exit_signals() linger on cset->tasks until their final
context switch, which led to a series of problems as what userspace expected
to see after rmdir diverged from what the kernel needs to wait for. [2]-[5]
tried to bridge that divergence: [2] filtered the exiting tasks from
cgroup.procs; [3] had rmdir(2) sleep in TASK_UNINTERRUPTIBLE for them; [4]
fixed the wait's condition; [5] made nr_dying_subsys_* visible
synchronously.
The cgroup_drain_dying() wait in [3] turned out to be a dead end. When the
rmdir caller is also the reaper of a zombie that pins a pidns teardown (e.g.
host PID 1 systemd reaping orphan pids that were re-parented to it during
the same teardown), rmdir blocks in TASK_UNINTERRUPTIBLE waiting for those
pids to free, the pids can't free because PID 1 is the reaper and it's stuck
in rmdir, and the system A-A deadlocks. No internal lock ordering breaks
this; the wait itself is the bug.
The css killing side that drove the original reorder, however, can be made
cleanly asynchronous: ->css_offline() is already async, run from
css_killed_work_fn() driven by percpu_ref_kill_and_confirm(). The fix is to
make that chain start only after all tasks have left the cgroup. rmdir's
user-visible side then returns as soon as cgroup.procs and friends are
empty, while ->css_offline() still runs only after the cgroup is fully
drained.
Verified by the original reproducer (pidns teardown + zombie reaper, runs
under vng) which hangs vanilla and succeeds here, and by per-commit
deterministic repros for [2], [3], [4], [5] with a boot parameter that
widens the post-exit_signals() window so each state is reliably reachable.
Some stress tests on top of that.
cgroup_apply_control_disable() has the same shape of pre-existing race:
when a controller is disabled via subtree_control, kill_css() ran
synchronously while tasks past exit_signals() could still be linked to
the cgroup's csets, and ->css_offline() could fire before they drained.
This patch preserves the existing synchronous behavior at that call site
(kill_css_sync() + kill_css_finish() back-to-back) and a follow-up patch
will defer kill_css_finish() there using a per-css trigger.
This seems like the right approach and I don't see problems with it. The
changes are somewhat invasive but not excessively so, so backporting to
-stable should be okay. If something does turn out to be wrong, the fallback
is to revert the entire chain ([1]-[5]) and rework in the development branch
instead.
v2: Pin cgrp across the deferred destroy work with explicit
cgroup_get()/cgroup_put() around queue_work() and the work_fn. v1
wasn't actually broken (ordered cgroup_offline_wq + queue_work order
in cgroup_task_dead() saved it) but the explicit ref removes the
dependency on those non-obvious invariants. Also note the
pre-existing cgroup_apply_control_disable() race in the description;
a follow-up will defer kill_css_finish() there.
Fixes: 1b164b876c ("cgroup: Wait for dying tasks to leave on rmdir")
Cc: stable@vger.kernel.org # v7.0+
Reported-and-tested-by: Martin Pitt <martin@piware.de>
Link: https://lore.kernel.org/all/afHNg2VX2jy9bW7y@piware.de/
Link: https://lore.kernel.org/all/35e0670adb4abeab13da2c321582af9f@kernel.org/
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
by Sebastian Andrzej Siewior.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'locking-urgent-2026-05-03' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull locking fix from Ingo Molnar:
"Fix lockup in requeue-PI during signal/timeout wakeups, by Sebastian
Andrzej Siewior"
* tag 'locking-urgent-2026-05-03' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
futex: Prevent lockup in requeue-PI during signal/ timeout wakeup
- Fix the delayed dequeue negative lag increase fix in the
fair scheduler (Peter Zijlstra)
- Fix wakeup_preempt_fair() to do proper delayed dequeue
(Vincent Guittot)
- Clear sched_entity::rel_deadline when initializing
forked entities, which bug can cause all tasks to be
EEVDF-ineligible, causing a NULL pointer dereference
crash in pick_next_entity() (Zicheng Qu)
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'sched-urgent-2026-05-03' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler fixes from Ingo Molnar:
- Fix the delayed dequeue negative lag increase fix in the
fair scheduler (Peter Zijlstra)
- Fix wakeup_preempt_fair() to do proper delayed dequeue
(Vincent Guittot)
- Clear sched_entity::rel_deadline when initializing
forked entities, which bug can cause all tasks to be
EEVDF-ineligible, causing a NULL pointer dereference
crash in pick_next_entity() (Zicheng Qu)
* tag 'sched-urgent-2026-05-03' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
sched/fair: Clear rel_deadline when initializing forked entities
sched/fair: Fix wakeup_preempt_fair() vs delayed dequeue
sched/fair: Fix the negative lag increase fix
Currently need_futex_hash_allocate_default() depends on strict pthread
semantics, abusing CLONE_THREAD. This breaks the non-concurrency
assumptions when doing the mm->futex_ref pcpu allocations, leading to
bugs[0] when sharing the mm in other ways; ie:
BUG: KASAN: slab-use-after-free in futex_hash_put
... where the +1 bias can end up on a percpu counter that mm->futex_ref
no longer points at.
Loosen the check to cover any CLONE_VM clone, except vfork(). Excluding
vfork keeps the existing paths untouched (no overhead), and we can't
race in the first place: either the parent is suspended and the child
runs alone, or mm->futex_ref is already allocated from an earlier
CLONE_VM.
Link: https://lore.kernel.org/all/CAL_bE8LsmCQ-FAtYDuwbJhOkt9p2wwYQwAbMh=PifC=VsiBM6A@mail.gmail.com/ [0]
Fixes: d9b05321e2 ("futex: Move futex_hash_free() back to __mmput()")
Reported-by: Yiming Qian <yimingqian591@gmail.com>
Signed-off-by: Davidlohr Bueso <dave@stgolabs.net>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
All alarmtimer users are converted to alarm_start_timer(). Remove the now
unused interfaces.
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Link: https://patch.msgid.link/20260408114952.670899355@kernel.org
Use the new alarm_start_timer() for arming and rearming posix interval
timers and for clock_nanosleep() so that already expired timers do not go
through the full timer interrupt cycle.
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Acked-by: John Stultz <jstultz@google.com>
Link: https://patch.msgid.link/20260408114952.400451460@kernel.org
Alarm timers utilize hrtimers for normal operation and only switch to the
RTC on suspend. In order to catch already expired timers early and without
going through a timer interrupt cycle, provide a new start function which
internally uses hrtimer_start_range_ns_user().
If hrtimer_start_range_ns_user() detects an already expired timer, it does
not queue it. In that case remove the timer from the alarm base as well.
Return the status queued or not back to the caller to handle the early
expiry.
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Acked-by: John Stultz <jstultz@google.com>
Link: https://patch.msgid.link/20260408114952.332822525@kernel.org
Switch the arm and rearm callbacks for hrtimer based posix timers over to
hrtimer_start_expires_user() so that already expired timers are not
queued. Hand the result back to the caller, which then queues the signal.
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260408114952.266001916@kernel.org
The [re]arm callbacks will return true when the timer was queued and false
if it was already expired at enqueue time.
In both cases the call sites can trivially queue the signal right there,
when the timer was already expired. That avoids a full round trip through
the hrtimer interrupt.
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260408114952.198028466@kernel.org
In order to catch expiry times which are already in the past the
timer_arm() and timer_rearm() callbacks need to be able to report back to
the caller whether the timer has been queued or not.
Change the function signature and let all implementations return true for
now. While at it simplify posix_cpu_timer_rearm().
No functional change intended.
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: John Stultz <jstultz@google.com>
Link: https://patch.msgid.link/20260408114952.130222296@kernel.org
Most hrtimer sleepers are user controlled and user space can hand arbitrary
expiry values in as long as they are valid timespecs. If the expiry value
is in the past then this requires a full loop through reprogramming the
clock event device, taking the hrtimer interrupt, waking the task and
reprogram again.
Use hrtimer_start_expires_user() which avoids the full round trip by
checking the timer for expiry on enqueue.
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Tested-by: Calvin Owens <calvin@wbinvd.org>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260408114952.062400833@kernel.org
Calvin reported an odd NMI watchdog lockup which claims that the CPU locked
up in user space. He provided a reproducer, which set's up a timerfd based
timer and then rearms it in a loop with an absolute expiry time of 1ns.
As the expiry time is in the past, the timer ends up as the first expiring
timer in the per CPU hrtimer base and the clockevent device is programmed
with the minimum delta value. If the machine is fast enough, this ends up
in a endless loop of programming the delta value to the minimum value
defined by the clock event device, before the timer interrupt can fire,
which starves the interrupt and consequently triggers the lockup detector
because the hrtimer callback of the lockup mechanism is never invoked.
The clockevents code already has a last resort mechanism to prevent that,
but it's sensible to catch such issues before trying to reprogram the clock
event device.
Provide a variant of hrtimer_start_range_ns(), which sanity checks the
timer after queueing it. It does not so before because the timer might be
armed and therefore needs to be dequeued. also we optimize for the latest
possible point to check, so that the clock event prevention is avoided as
much as possible.
If the timer is already expired _before_ the clock event is reprogrammed,
remove the timer from the queue and signal to the caller that the operation
failed by returning false.
That allows the caller to take immediate action without going through the
loops and hoops of the hrtimer interrupt.
The queueing code can't invoke the timer callback as the caller might hold
a lock which is taken in the callback.
Add a tracepoint which allows to analyze the expired at start situation.
Reported-by: Calvin Owens <calvin@wbinvd.org>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Tested-by: Calvin Owens <calvin@wbinvd.org>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260408114951.995031895@kernel.org
If time slice extensions have been disabled on the kernel command line,
then advertising them in RSEQ flags is wrong.
Adjust the conditionals to reflect reality, fixup the misleading comments
about the gap of these flags and the rseq::flags field.
Fixes: d6200245c7 ("rseq: Allow registering RSEQ with slice extension")
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
Tested-by: Dmitry Vyukov <dvyukov@google.com>
Link: https://patch.msgid.link/20260428224427.437059375%40kernel.org
Cc: stable@vger.kernel.org
The RSEQ rework changed that to RSEQ_CPU_UNINITILIZED, which is obviously
incompatible. Revert back to the original behavior.
Fixes: 0f085b4188 ("rseq: Provide and use rseq_set_ids()")
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
Tested-by: Dmitry Vyukov <dvyukov@google.com>
Link: https://patch.msgid.link/20260428224427.271566313%40kernel.org
Cc: stable@vger.kernel.org
and the remainder are for post-7.0 issues or aren't deemed suitable for
backporting.
There's a 2 patch DAMON series from SeongJae Park which address races
which could lead to use-after-free errors. And a 3 patch DAMON series
which avoids the possibility of presenting stale parameter values to
users.
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Merge tag 'mm-hotfixes-stable-2026-04-30-15-39' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Pull MM fixes from Andrew Morton:
"20 hotfixes. All are for MM (and for MMish maintainers). 9 are
cc:stable and the remainder are for post-7.0 issues or aren't deemed
suitable for backporting.
There are two DAMON series from SeongJae Park which address races
which could lead to use-after-free errors, and avoid the possibility
of presenting stale parameter values to users"
* tag 'mm-hotfixes-stable-2026-04-30-15-39' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm:
mm: memcontrol: fix rcu unbalance in get_non_dying_memcg_end()
mm/userfaultfd: detect VMA type change after copy retry in mfill_copy_folio_retry()
MAINTAINERS: remove stale kdump project URL
mm/damon/stat: detect and use fresh enabled value
mm/damon/lru_sort: detect and use fresh enabled and kdamond_pid values
mm/damon/reclaim: detect and use fresh enabled and kdamond_pid values
selftests/mm: specify requirement for PROC_MEM_ALWAYS_FORCE=y
mm/damon/sysfs-schemes: protect path kfree() with damon_sysfs_lock
mm/damon/sysfs-schemes: protect memcg_path kfree() with damon_sysfs_lock
MAINTAINERS: update Li Wang's email address
MAINTAINERS, mailmap: update email address for Qi Zheng
MAINTAINERS: update Liam's email address
mm/hugetlb_cma: round up per_node before logging it
MAINTAINERS: fix regex pattern in CORE MM category
mm/vma: do not try to unmap a VMA if mmap_prepare() invoked from mmap()
mm: start background writeback based on per-wb threshold for strictlimit BDIs
kho: fix error handling in kho_add_subtree()
liveupdate: fix return value on session allocation failure
mailmap: update entry for Dan Carpenter
vmalloc: fix buffer overflow in vrealloc_node_align()
When using global functions (i.e. subprogs), the verifier performs
function-by-function verification. In that case, the sum of the
instructions processed in each global function and in the main program
counts towards the 1 million instructions limit. Only that sum is
reported in the verifier logs.
While starting to use global functions in Cilium (finally!), we found it
can be useful to have the breakdown per global function, to understand
exactly where the budget is currently spent. This patch implements this
breakdown, under BPF_LOG_STATS, as done for the stack depths.
When iterating over subprogs, we need to skip the hidden subprogs at the
end because they don't have a corresponding func_info_aux entry and
calling bpf_subprog_is_global() would result in an OOB access.
Signed-off-by: Paul Chaignon <paul.chaignon@gmail.com>
Link: https://lore.kernel.org/bpf/5590f9c67e614ec9054d0c7e74e87cc690a52c56.1777538384.git.paul.chaignon@gmail.com
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Calculate the correct physical address of the last byte of memory. Since
max_pfn is in fact "the PFN of the first page after the highest system RAM
in physical address space", the highest address that might be used for a
DMA buffer is one byte below max_pfn << PAGE_SHIFT.
This fix is unlikely to make any difference in practice. It's just that the
current formula is slightly confusing.
Signed-off-by: Petr Tesarik <ptesarik@suse.com>
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Link: https://lore.kernel.org/r/20260410113506.262579-1-ptesarik@suse.com
- Fix inverted check of registering the stats for branch tracing
When calling register_stat_tracer() which returns zero on success and
negative on error, the callers were checking the return of zero as an
error and printing a warning message. Because this was just a normal
printk() message and not a WARN(), it wasn't caught in any testing.
Fix the check to print the warning message when an error actually happens.
- Fix a typo in a comment in tracepoint.h
- Limit the size of event probes to 3K in size
It is possible to create a dynamic event probe via the tracefs system that
is greater than the max size of an event that the ring buffer can hold.
This basically causes the event to become useless. Limit the size of an
event probe to be 3K as that should be large enough to handle any dynamic
events being created, and fits within the PAGE_SIZE sub-buffers of the
ring buffer.
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Merge tag 'trace-v7.1-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace
Pull tracing fixes from Steven Rostedt:
- Fix inverted check of registering the stats for branch tracing
When calling register_stat_tracer() which returns zero on success and
negative on error, the callers were checking the return of zero as an
error and printing a warning message. Because this was just a normal
printk() message and not a WARN(), it wasn't caught in any testing.
Fix the check to print the warning message when an error actually
happens.
- Fix a typo in a comment in tracepoint.h
- Limit the size of event probes to 3K in size
It is possible to create a dynamic event probe via the tracefs system
that is greater than the max size of an event that the ring buffer
can hold. This basically causes the event to become useless.
Limit the size of an event probe to be 3K as that should be large
enough to handle any dynamic events being created, and fits within
the PAGE_SIZE sub-buffers of the ring buffer.
* tag 'trace-v7.1-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
tracing/probes: Limit size of event probe to 3K
tracepoint: Fix typo in tracepoint.h comment
tracing: branch: Fix inverted check on stat tracer registration
There currently isn't a max limit an event probe can be. One could make an
event greater than PAGE_SIZE, which makes the event useless because if
it's bigger than the max event that can be recorded into the ring buffer,
then it will never be recorded.
A event probe should never need to be greater than 3K, so make that the
max size. As long as the max is less than the max that can be recorded
onto the ring buffer, it should be fine.
Cc: stable@vger.kernel.org
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Fixes: 93ccae7a22 ("tracing/kprobes: Support basic types on dynamic events")
Link: https://patch.msgid.link/20260428122302.706610ba@gandalf.local.home
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
alloc_workqueue_va() forwards its va_list to __alloc_workqueue() which
ultimately feeds vsnprintf(). __alloc_workqueue() already carries
__printf(1, 0); the new wrapper needs the same annotation so format
string checking propagates through the forwarding.
Fixes: 0de4cb473a ("workqueue: fix devm_alloc_workqueue() va_list misuse")
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202604300347.2LgXyteh-lkp@intel.com/
Signed-off-by: Tejun Heo <tj@kernel.org>
Sub-scheduler support is tied to the cid-form struct_ops: sub_attach /
sub_detach will communicate allocation via cmask, and the hierarchy assumes
all participants share a single topological cid space. A cpu-form root that
accepts sub-scheds would need cpu <-> cid translation on every cross-sched
interaction, defeating the purpose.
Enforce this at validate_ops():
- A sub-scheduler (scx_parent(sch) non-NULL) must be cid-form.
- A root that exposes sub_attach / sub_detach must be cid-form.
scx_qmap, which is currently the only scheduler demoing sub-sched support,
was converted to cid-form in the preceding patch, so this doesn't cause
breakage.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Cheng-Yang Chou <yphbchou0911@gmail.com>
Reviewed-by: Changwoo Min <changwoo@igalia.com>
Reviewed-by: Andrea Righi <arighi@nvidia.com>
cid and cpu are both small s32s, trivially confused when a cid-form
scheduler calls a cpu-keyed kfunc. Reject cid-form programs that
reference any kfunc in the new scx_kfunc_ids_cpu_only at verifier load
time.
The reverse direction is intentionally permissive: cpu-form schedulers
can freely call cid-form kfuncs to ease a gradual cpumask -> cid
migration.
The check sits in scx_kfunc_context_filter() right after the SCX
struct_ops gate and before the any/idle allow and per-op allow-list
checks, so it catches cpu-only kfuncs regardless of which set they
belong to (any, idle, or select_cpu).
v2: Sync per-entry kfunc flags with their primary declarations (Zhao).
pahole intersects flags across BTF_ID_FLAGS() occurrences, so
omitting them drops the flags globally.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Cheng-Yang Chou <yphbchou0911@gmail.com>
Reviewed-by: Zhao Mengmeng <zhaomengmeng@kylinos.cn>
Reviewed-by: Changwoo Min <changwoo@igalia.com>
Reviewed-by: Andrea Righi <arighi@nvidia.com>
cpumask is awkward from BPF and unusable from arena; cid/cmask work in
both. Sub-sched enqueue will need cmask. Without a full cid interface,
schedulers end up mixing forms - a subtle-bug factory.
Add sched_ext_ops_cid, which mirrors sched_ext_ops with cid/cmask
replacing cpu/cpumask in the topology-carrying callbacks.
cpu_acquire/cpu_release are deprecated and absent; a prior patch
moved them past @priv so the cid-form can omit them without
disturbing shared-field offsets.
The two structs share byte-identical layout up to @priv, so the
existing bpf_scx init/check hooks, has_op bitmap, and
scx_kf_allow_flags[] are offset-indexed and apply to both.
BUILD_BUG_ON in scx_init() pins the shared-field and renamed-callback
offsets so any future drift trips at boot.
The kernel<->BPF boundary translates between cpu and cid:
- A static key, enabled on cid-form sched load, gates the translation
so cpu-form schedulers pay nothing.
- dispatch, update_idle, cpu_online/offline and dump_cpu translate
the cpu arg at the callsite.
- select_cpu also translates the returned cid back to a cpu.
- set_cpumask is wrapped to synthesize a cmask in a per-cpu scratch
before calling the cid-form callback.
All scheds in a hierarchy share one form. The static key drives the
hot-path branch.
v2: Use struct_size() for the set_cmask_scratch percpu alloc. Move
cid-shard fields and assertions into the later cid-shard patch.
v3: Drop `static` on scx_set_cmask_scratch; add extern in ext_internal.h.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Cheng-Yang Chou <yphbchou0911@gmail.com>
Reviewed-by: Changwoo Min <changwoo@igalia.com>
Reviewed-by: Andrea Righi <arighi@nvidia.com>
cpumask is awkward from BPF and unusable from arena; cid/cmask work in
both. Sub-sched enqueue will need cmask. Without full cid coverage a
scheduler has to mix cid and cpu forms, which is a subtle-bug factory.
Close the gap with a cid-native interface.
Pair every cpu-form kfunc that takes a cpu id with a cid-form
equivalent (kick, task placement, cpuperf query/set, per-cpu current
task, nr-cpu-ids). Add two cid-natives with no cpu-form sibling:
scx_bpf_this_cid() (cid of the running cpu, scx equivalent of
bpf_get_smp_processor_id) and scx_bpf_nr_online_cids().
scx_bpf_cpu_rq is deprecated; no cid-form counterpart. NUMA node info
is reachable via scx_bpf_cid_topo() on the BPF side.
Each cid-form wrapper is a thin cid -> cpu translation that delegates
to the cpu path, registered in the same context sets so usage
constraints match.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Cheng-Yang Chou <yphbchou0911@gmail.com>
Reviewed-by: Changwoo Min <changwoo@igalia.com>
Reviewed-by: Andrea Righi <arighi@nvidia.com>
Sub-scheduler code built on cids needs bitmaps scoped to a slice of cid
space (e.g. the idle cids of a shard). A cpumask sized for NR_CPUS wastes
most of its bits for a small window and is awkward in BPF.
scx_cmask covers [base, base + nr_bits). bits[] is aligned to the global
64-cid grid: bits[0] spans [base & ~63, (base & ~63) + 64). Any two
cmasks therefore address bits[] against the same global windows, so
cross-cmask word ops reduce to
dest->bits[i] OP= operand->bits[i - delta]
with no bit-shifting, at the cost of up to one extra storage word for
head misalignment. This alignment guarantee is the reason binary ops
can stay word-level; every mutating helper preserves it.
Kernel side in ext_cid.[hc]; BPF side in tools/sched_ext/include/scx/
cid.bpf.h. BPF side drops the scx_ prefix (redundant in BPF code) and
adds the extra helpers that basic idle-cpu selection needs.
No callers yet.
v2: Narrow to helpers that will be used in the planned changes;
set/bit/find/zero ops will be added as usage develops.
v3: cmask_copy_from_kernel: validate src->base == 0 via probe-read;
bit-level nr_bits check instead of round-up word count. (Sashiko)
v4: Bump CMASK_CAS_TRIES to 1<<23 so abort fires only after seconds
of real spinning, not on plausible contention. Switch
__builtin_ctzll() to the ctzll() wrapper for clang compat
(Changwoo).
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Cheng-Yang Chou <yphbchou0911@gmail.com>
Reviewed-by: Changwoo Min <changwoo@igalia.com>
Reviewed-by: Andrea Righi <arighi@nvidia.com>
The auto-probed cid mapping reflects the kernel's view of topology
(node -> LLC -> core), but a BPF scheduler may want a different layout -
to align cid slices with its own partitioning, or to work around how the
kernel reports a particular machine.
Add scx_bpf_cid_override(), callable from ops.init() of the root
scheduler. It validates the caller-supplied cpu->cid array and replaces
the in-place mapping; topo info is invalidated. A compat.bpf.h wrapper
silently no-ops on kernels that lack the kfunc.
A new SCX_KF_ALLOW_INIT bit in the kfunc context filter restricts the
kfunc to ops.init() at verifier load time.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Cheng-Yang Chou <yphbchou0911@gmail.com>
Reviewed-by: Changwoo Min <changwoo@igalia.com>
Raw cpu numbers are clumsy for sharding and cross-sched communication,
especially from BPF. The space is sparse, numerical closeness doesn't
track topological closeness (x86 hyperthreading often scatters SMT
siblings), and a range of cpu ids doesn't describe anything meaningful.
Sub-sched support makes this acute: cpu allocation, revocation, and
state constantly flow across sub-scheds. Passing whole cpumasks scales
poorly (every op scans 4K bits) and cpumasks are awkward in BPF.
cids assign every cpu a dense, topology-ordered id. CPUs sharing a core,
LLC, or NUMA node occupy contiguous cid ranges, so a topology unit
becomes a (start, length) slice. Communication passes slices; BPF can
process a u64 word of cids at a time.
Build the mapping once at root enable by walking online cpus node -> LLC
-> core. Possible-but-not-online cpus tail the space with no-topo cids.
Expose kfuncs to map cpu <-> cid in either direction and to query each
cid's topology metadata.
v2: Use kzalloc_objs()/kmalloc_objs() for the three allocs in
scx_cid_arrays_alloc() (Cheng-Yang Chou).
v3: scx_cid_init() failure path now drops cpus_read_lock();
BUILD_BUG_ON tightened to match BPF cmask helpers' NR_CPUS<=8192.
(Sashiko)
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Cheng-Yang Chou <yphbchou0911@gmail.com>
Reviewed-by: Changwoo Min <changwoo@igalia.com>
Reviewed-by: Andrea Righi <arighi@nvidia.com>
Pass struct scx_enable_cmd to scx_enable() rather than unpacking @ops
at every call site and re-packing into a fresh cmd inside. bpf_scx_reg()
now builds the cmd on its stack and hands it in; scx_enable() just
wires up the kthread work and waits.
Relocate struct scx_enable_cmd above scx_alloc_and_add_sched() so
upcoming patches that also want the cmd can see it.
No behavior change.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Cheng-Yang Chou <yphbchou0911@gmail.com>
Reviewed-by: Changwoo Min <changwoo@igalia.com>
Reviewed-by: Andrea Righi <arighi@nvidia.com>
cpu_acquire and cpu_release are deprecated and slated for removal. Move
their declarations to the end of struct sched_ext_ops so an upcoming
cid-form struct (sched_ext_ops_cid) can omit them entirely without
disturbing the offsets of the shared fields.
Switch the two SCX_HAS_OP() callers for these ops to direct field checks
since the relocated ops sit outside the SCX_OPI_END range covered by the
has_op bitmap.
scx_kf_allow_flags[] auto-sizes to the highest used SCX_OP_IDX, so
SCX_OP_IDX(cpu_release) moving to a higher index just enlarges the
sparse array; the lookup logic is unchanged.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Cheng-Yang Chou <yphbchou0911@gmail.com>
Reviewed-by: Changwoo Min <changwoo@igalia.com>
Reviewed-by: Andrea Righi <arighi@nvidia.com>
Callers that already know the cpu is valid shouldn't have to pay for a
redundant check. scx_kick_cpu() is called from the in-kernel balance loop
break-out path with the current cpu (trivially valid) and from
scx_bpf_kick_cpu() with a BPF-supplied cpu that does need validation. Move
the check out of scx_kick_cpu() into scx_bpf_kick_cpu() so the backend is
reusable by callers that have already validated.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Cheng-Yang Chou <yphbchou0911@gmail.com>
Reviewed-by: Changwoo Min <changwoo@igalia.com>
Reviewed-by: Andrea Righi <arighi@nvidia.com>
Things shared across multiple .c files belong in a header. scx_exit() /
scx_error() (and their scx_vexit() / scx_verror() siblings) are already
called from ext_idle.c and the upcoming ext_cid.c, and it was only
build_policy.c's textual inclusion of ext.c that made the references
resolve. Move the whole family to ext_internal.h.
Pure visibility change.
v4: Rebased over the exit_cpu plumbing. scx_exit() and scx_verror()
are now macros wrapping raw_smp_processor_id(); move both macros
plus the underlying __scx_exit() / scx_vexit() declarations to
the header.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Cheng-Yang Chou <yphbchou0911@gmail.com>
Reviewed-by: Changwoo Min <changwoo@igalia.com>
Reviewed-by: Andrea Righi <arighi@nvidia.com>
Rename the static ext.c helper and declare it in ext_internal.h so
ext_idle.c and the upcoming cid code can call it directly instead of
relying on build_policy.c textual inclusion.
Pure rename and visibility change.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Cheng-Yang Chou <yphbchou0911@gmail.com>
Reviewed-by: Changwoo Min <changwoo@igalia.com>
Reviewed-by: Andrea Righi <arighi@nvidia.com>
Introduce kernel/sched/ext_types.h as the early-def header for the
sched_ext compilation unit. Included from kernel/sched/build_policy.c
before ext_internal.h so every later header and source in the unit
sees its content without re-inclusion. Later patches add their types
here (struct scx_cid_topo, scx_cmask, scx_cid_shard, etc.) so the
subsystem has one place to stash types shared across the TU.
Move enum scx_consts (SCX_DSP_DFL_MAX_BATCH, SCX_WATCHDOG_MAX_TIMEOUT,
SCX_SUB_MAX_DEPTH, etc.) here as the initial content. Ops-facing
content stays in ext_internal.h.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Changwoo Min <changwoo@igalia.com>
Reviewed-by: Andrea Righi <arighi@nvidia.com>
When sched_ext is disabled by an error, the CPU that triggered the exit
is the most relevant piece of information for diagnosing the problem.
However, if there are many CPUs, the dump can get truncated and that
CPU's information may not appear in the output.
Add an exit_cpu field to scx_exit_info and thread it through scx_vexit()
/ __scx_exit(). For the watchdog stall path, populate it from cpu_of(rq)
in check_rq_for_timeouts(). For all other exit paths, define a scx_exit()
macro that wraps __scx_exit() with raw_smp_processor_id(), so the CPU
that initiated the exit is captured automatically, with no call-site
changes needed.
In scx_dump_state(), report the exit CPU in the dump header ("on cpu N")
and dump that CPU first, skipping it in the per-CPU loop, so the most
relevant CPU is never truncated out of the dump. The SysRq-D path
initializes exit_cpu to -1 so debug dumps not tied to an exit don't
arbitrarily promote CPU 0.
Signed-off-by: Changwoo Min <changwoo@igalia.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Factor out the per-CPU state dump logic from the for_each_possible_cpu
loop in scx_dump_state() into a new scx_dump_cpu() helper to improve
readability. No functional change.
Signed-off-by: Changwoo Min <changwoo@igalia.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
During wait-requeue-pi (task A) and requeue-PI (task B) the following
race can happen:
Task A Task B
futex_wait_requeue_pi()
futex_setup_timer()
futex_do_wait()
futex_requeue()
CLASS(hb, hb1)(&key1);
CLASS(hb, hb2)(&key2);
*timeout*
futex_requeue_pi_wakeup_sync()
requeue_state = Q_REQUEUE_PI_IGNORE
*blocks on hb->lock*
futex_proxy_trylock_atomic()
futex_requeue_pi_prepare()
Q_REQUEUE_PI_IGNORE => -EAGAIN
double_unlock_hb(hb1, hb2)
*retry*
Task B acquires both hb locks and attempts to acquire the PI-lock of the
top most waiter (task B). Task A is leaving early due to a signal/
timeout and started removing itself from the queue. It updates its
requeue_state but can not remove it from the list because this requires
the hb lock which is owned by task B.
Usually task A is able to swoop the lock after task B unlocked it.
However if task B is of higher priority then task A may not be able to
wake up in time and acquire the lock before task B gets it again.
Especially on a UP system where A is never scheduled.
As a result task A blocks on the lock and task B busy loops, trying to
make progress but live locks the system instead. Tragic.
This can be fixed by removing the top most waiter from the list in this
case. This allows task B to grab the next top waiter (if any) in the
next iteration and make progress.
Remove the top most waiter if futex_requeue_pi_prepare() fails.
Let the waiter conditionally remove itself from the list in
handle_early_requeue_pi_wakeup().
Fixes: 07d91ef510 ("futex: Prevent requeue_pi() lock nesting issue on RT")
Reported-by: Moritz Klammler <Moritz.Klammler@ferchau.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Link: https://patch.msgid.link/20260428103425.dywXyPd3@linutronix.de
Closes: https://lore.kernel.org/all/VE1PR06MB6894BE61C173D802365BE19DFF4CA@VE1PR06MB6894.eurprd06.prod.outlook.com
The merge window pulled in the cgroup sub-scheduler infrastructure, and
new AI reviews are accelerating bug reporting and fixing - hence the
larger than usual fixes batch.
- Use-after-frees during scheduler load/unload. The disable path
could free the BPF scheduler while deferred irq_work / kthread work
was still in flight; cgroup setter callbacks read the active
scheduler outside the rwsem that synchronizes against teardown.
Fixed both, and reused the disable drain in the enable error paths
so the BPF JIT page can't be freed under live callbacks.
- Several BPF op invocations didn't tell the framework which runqueue
was already locked, so helper kfuncs that re-acquire the runqueue
by CPU could deadlock on the held lock. Fixed at the affected
callsites, including recursive parent-into-child dispatch.
- The hardlockup notifier ran from NMI but eventually took a
non-NMI-safe lock. Bounced through irq_work.
- A handful of bugs in the new sub-scheduler hierarchy: helper
kfuncs hard-coded the root instead of resolving the caller's
scheduler; the enable error path tried to disable per-task state
that had never been initialized, and leaked cpus_read_lock on the
way out; a sysfs object was leaked on every load/unload; the
dispatch fast-path used the root scheduler instead of the task's;
and a couple of CONFIG #ifdef guards were misclassified.
- Verifier-time hardening: BPF programs of unrelated struct_ops
types (e.g. tcp_congestion_ops) could call sched_ext kfuncs - a
semantic bug and, once sub-sched was enabled, a KASAN
out-of-bounds read. Now rejected at load. Plus a few NULL and
cross-task argument checks on sched_ext kfuncs, and a selftest
covering the new deny.
- rhashtable (Herbert): restored the insecure_elasticity toggle and
bounced the deferred-resize kick through irq_work to break a
lock-order cycle observable from raw-spinlock callers. sched_ext's
scheduler-instance hash is the first user of both.
- The bypass-mode load balancer used file-scope cpumasks; with
multiple scheduler instances now possible, those raced. Moved
per-instance, plus a follow-up to skip tasks whose recorded CPU is
stale relative to the new owning runqueue.
- Smaller fixes: a dispatch queue's first-task tracking misbehaved
when a parked iterator cursor sat in the list; the runqueue's
next-class wasn't promoted on local-queue enqueue, leaving an SCX
task behind RT in edge cases; the reference qmap scheduler stopped
erroring on legitimate cross-scheduler task-storage misses.
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Merge tag 'sched_ext-for-7.1-rc1-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/sched_ext
Pull sched_ext fixes from Tejun Heo:
"The merge window pulled in the cgroup sub-scheduler infrastructure,
and new AI reviews are accelerating bug reporting and fixing - hence
the larger than usual fixes batch:
- Use-after-frees during scheduler load/unload:
- The disable path could free the BPF scheduler while deferred
irq_work / kthread work was still in flight
- cgroup setter callbacks read the active scheduler outside the
rwsem that synchronizes against teardown
Fix both, and reuse the disable drain in the enable error paths so
the BPF JIT page can't be freed under live callbacks.
- Several BPF op invocations didn't tell the framework which runqueue
was already locked, so helper kfuncs that re-acquire the runqueue
by CPU could deadlock on the held lock
Fix the affected callsites, including recursive parent-into-child
dispatch.
- The hardlockup notifier ran from NMI but eventually took a
non-NMI-safe lock. Bounce it through irq_work.
- A handful of bugs in the new sub-scheduler hierarchy:
- helper kfuncs hard-coded the root instead of resolving the
caller's scheduler
- the enable error path tried to disable per-task state that had
never been initialized, and leaked cpus_read_lock on the way
out
- a sysfs object was leaked on every load/unload
- the dispatch fast-path used the root scheduler instead of the
task's
- a couple of CONFIG #ifdef guards were misclassified
- Verifier-time hardening: BPF programs of unrelated struct_ops types
(e.g. tcp_congestion_ops) could call sched_ext kfuncs - a semantic
bug and, once sub-sched was enabled, a KASAN out-of-bounds read.
Now rejected at load. Plus a few NULL and cross-task argument
checks on sched_ext kfuncs, and a selftest covering the new deny.
- rhashtable (Herbert): restore the insecure_elasticity toggle and
bounce the deferred-resize kick through irq_work to break a
lock-order cycle observable from raw-spinlock callers. sched_ext's
scheduler-instance hash is the first user of both.
- The bypass-mode load balancer used file-scope cpumasks; with
multiple scheduler instances now possible, those raced. Move to
per-instance cpumasks, plus a follow-up to skip tasks whose
recorded CPU is stale relative to the new owning runqueue.
- Smaller fixes:
- a dispatch queue's first-task tracking misbehaved when a parked
iterator cursor sat in the list
- the runqueue's next-class wasn't promoted on local-queue
enqueue, leaving an SCX task behind RT in edge cases
- the reference qmap scheduler stopped erroring on legitimate
cross-scheduler task-storage misses"
* tag 'sched_ext-for-7.1-rc1-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/sched_ext: (26 commits)
sched_ext: Fix scx_flush_disable_work() UAF race
sched_ext: Call wakeup_preempt() in local_dsq_post_enq()
sched_ext: Release cpus_read_lock on scx_link_sched() failure in root enable
sched_ext: Reject NULL-sch callers in scx_bpf_task_set_slice/dsq_vtime
sched_ext: Refuse cross-task select_cpu_from_kfunc calls
sched_ext: Align cgroup #ifdef guards with SUB_SCHED vs GROUP_SCHED
sched_ext: Make bypass LB cpumasks per-scheduler
sched_ext: Pass held rq to SCX_CALL_OP() for core_sched_before
sched_ext: Pass held rq to SCX_CALL_OP() for dump_cpu/dump_task
sched_ext: Save and restore scx_locked_rq across SCX_CALL_OP
sched_ext: Use dsq->first_task instead of list_empty() in dispatch_enqueue() FIFO-tail
sched_ext: Resolve caller's scheduler in scx_bpf_destroy_dsq() / scx_bpf_dsq_nr_queued()
sched_ext: Read scx_root under scx_cgroup_ops_rwsem in cgroup setters
sched_ext: Don't disable tasks in scx_sub_enable_workfn() abort path
sched_ext: Skip tasks with stale task_rq in bypass_lb_cpu()
sched_ext: Guard scx_dsq_move() against NULL kit->dsq after failed iter_new
sched_ext: Unregister sub_kset on scheduler disable
sched_ext: Defer scx_hardlockup() out of NMI
sched_ext: sync disable_irq_work in bpf_scx_unreg()
sched_ext: Fix local_dsq_post_enq() to use task's scheduler in sub-sched
...
init_annotated_branch_stats() and all_annotated_branch_stats() check the
return value of register_stat_tracer() with "if (!ret)", but
register_stat_tracer() returns 0 on success and a negative errno on
failure. The inverted check causes the warning to be printed on every
successful registration, e.g.:
Warning: could not register annotated branches stats
while leaving real failures silent. The initcall also returned a
hard-coded 1 instead of the actual error.
Invert the check and propagate ret so that the warning fires on real
errors and the initcall reports the correct status.
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Link: https://patch.msgid.link/20260420-tracing-v1-1-d8f4cd0d6af1@debian.org
Fixes: 002bb86d8d ("tracing/ftrace: separate events tracing and stats tracing engine")
Signed-off-by: Breno Leitao <leitao@debian.org>
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
scx_flush_disable_work() calls irq_work_sync() followed by
kthread_flush_work() to ensure that the disable kthread work has
fully completed before bpf_scx_unreg() frees the SCX scheduler.
However, a concurrent scx_vexit() (e.g., triggered by a watchdog stall)
creates a race window between scx_claim_exit() and irq_work_queue():
CPU A (scx_vexit (watchdog)) CPU B (bpf_scx_unreg)
---- ----
scx_claim_exit()
atomic_try_cmpxchg(NONE->kind)
stack_trace_save()
vscnprintf()
scx_disable()
scx_claim_exit() -> FAIL
scx_flush_disable_work()
irq_work_sync() // no-op: not queued yet
kthread_flush_work() // no-op: not queued yet
kobject_put(&sch->kobj) -> free %sch
irq_work_queue() -> UAF on %sch
scx_disable_irq_workfn()
kthread_queue_work() -> UAF
The root cause is that CPU B's scx_flush_disable_work() returns after
syncing an irq_work that has not yet been queued, while CPU A is still
executing the code between scx_claim_exit() and irq_work_queue().
Loop until exit_kind reaches SCX_EXIT_DONE or SCX_EXIT_NONE, draining
disable_irq_work and disable_work in each pass. This ensures that any
work queued after the previous check is caught, while also correctly
handling cases where no disable was triggered (e.g., the
scx_sub_enable_workfn() abort path).
Fixes: 510a270554 ("sched_ext: sync disable_irq_work in bpf_scx_unreg()")
Reported-by: https://sashiko.dev/#/patchset/20260424100221.32407-1-icheng%40nvidia.com
Suggested-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Cheng-Yang Chou <yphbchou0911@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Move <linux/btf_ids.h> from ext.c and "ext_idle.h" from ext.c (plus its
self-include in ext_idle.c) into build_policy.c. Subsequent patches add
their headers the same way for consistency.
No functional change.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Andrea Righi <arighi@nvidia.com>
There are several edge cases (see linked thread) where an IMMED task
can be left lingering on a local DSQ if an RT task swoops in at the
wrong time. All of these edge cases are due to rq->next_class being idle
even after dispatching a task to rq's local DSQ. We should bump
rq->next_class to &ext_sched_class as soon as we've inserted a task into
the local DSQ.
To optimize the common case of rq->next_class == &ext_sched_class,
only call wakeup_preempt() if rq->next_class is below EXT. If next_class
is EXT or above, wakeup_preempt() is a no-op anyway.
This lets us also simplify the preempt_curr() logic a bit since
wakeup_preempt() will call preempt_curr() for us if next_class is
below EXT.
Link: https://lore.kernel.org/all/DHZPHUFXB4N3.2RY28MUEWBNYK@google.com/
Signed-off-by: Kuba Piecuch <jpiecuch@google.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
devm_alloc_workqueue() built a va_list and passed it as a single
positional argument to the variadic alloc_workqueue() macro:
va_start(args, max_active);
wq = alloc_workqueue(fmt, flags, max_active, args);
va_end(args);
C does not allow forwarding a va_list through a ... parameter.
alloc_workqueue() expands to alloc_workqueue_noprof(), which runs
its own va_start() over its ... params, so the inner
vsnprintf(wq->name, sizeof(wq->name), fmt, args) in
__alloc_workqueue() received the outer va_list object as the first
variadic slot rather than the caller's actual format arguments.
Add a new static helper alloc_workqueue_va() that wraps
__alloc_workqueue() and runs wq_init_lockdep() on success, and
fold both alloc_workqueue_noprof() and devm_alloc_workqueue_noprof()
onto it as suggested by Tejun.
The wq_init_lockdep() step is required on the devm path
too, otherwise __flush_workqueue()'s on-stack
COMPLETION_INITIALIZER_ONSTACK_MAP would NULL-deref wq->lockdep_map.
No caller changes are required. devm_alloc_ordered_workqueue() is
a macro forwarding to devm_alloc_workqueue() and inherits the fix.
Two in-tree callers actively trigger the broken path on every probe:
drivers/power/supply/mt6370-charger.c:889
drivers/power/supply/max77705_charger.c:649
both of which use devm_alloc_ordered_workqueue(dev, "%s", 0,
dev_name(dev)).
A standalone reproducer module is available at[1].
Link: https://github.com/leitao/debug/blob/main/workqueue/valist/wq_va_test.c [1]
Fixes: 1dfc9d60a6 ("workqueue: devres: Add device-managed allocate workqueue")
Signed-off-by: Breno Leitao <leitao@debian.org>
Signed-off-by: Tejun Heo <tj@kernel.org>
kho_fill_kimage() unconditionally populates the kimage with KHO
metadata for every kexec image type. When the image is a crash kernel,
this can be problematic as the crash kernel can run in a small reserved
region and the KHO scratch areas can sit outside it.
The crash kernel then faults during kho_memory_init() when it
tries phys_to_virt() on the KHO FDT address:
Unable to handle kernel paging request at virtual address xxxxxxxx
...
fdt_offset_ptr+...
fdt_check_node_offset_+...
fdt_first_property_offset+...
fdt_get_property_namelen_+...
fdt_getprop+...
kho_memory_init+...
mm_core_init+...
start_kernel+...
kho_locate_mem_hole() already skips KHO logic for KEXEC_TYPE_CRASH
images, but kho_fill_kimage() was missing the same guard. As
kho_fill_kimage() is the single point that populates image->kho.fdt
and image->kho.scratch, fixing it here is sufficient for both arm64
and x86 as the FDT and boot_params path are bailing out when these
fields are unset.
Fixes: d7255959b6 ("kho: allow kexec load before KHO finalization")
Signed-off-by: Evangelos Petrongonas <epetron@amazon.de>
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Link: https://patch.msgid.link/20260410011609.1103-1-epetron@amazon.de
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
A yield-triggered crash can happen when a newly forked sched_entity
enters the fair class with se->rel_deadline unexpectedly set.
The failing sequence is:
1. A task is forked while se->rel_deadline is still set.
2. __sched_fork() initializes vruntime, vlag and other sched_entity
state, but does not clear rel_deadline.
3. On the first enqueue, enqueue_entity() calls place_entity().
4. Because se->rel_deadline is set, place_entity() treats se->deadline
as a relative deadline and converts it to an absolute deadline by
adding the current vruntime.
5. However, the forked entity's deadline is not a valid inherited
relative deadline for this new scheduling instance, so the conversion
produces an abnormally large deadline.
6. If the task later calls sched_yield(), yield_task_fair() advances
se->vruntime to se->deadline.
7. The inflated vruntime is then used by the following enqueue path,
where the vruntime-derived key can overflow when multiplied by the
entity weight.
8. This corrupts cfs_rq->sum_w_vruntime, breaks EEVDF eligibility
calculation, and can eventually make all entities appear ineligible.
pick_next_entity() may then return NULL unexpectedly, leading to a
later NULL dereference.
A captured trace shows the effect clearly. Before yield, the entity's
vruntime was around:
9834017729983308
After yield_task_fair() executed:
se->vruntime = se->deadline
the vruntime jumped to:
19668035460670230
and the deadline was later advanced further to:
19668035463470230
This shows that the deadline had already become abnormally large before
yield_task_fair() copied it into vruntime.
rel_deadline is only meaningful when se->deadline really carries a
relative deadline that still needs to be placed against vruntime. A
freshly forked sched_entity should not inherit or retain this state.
Clear se->rel_deadline in __sched_fork(), together with the other
sched_entity runtime state, so that the first enqueue does not interpret
the new entity's deadline as a stale relative deadline.
Fixes: 82e9d0456e ("sched/fair: Avoid re-setting virtual deadline on 'migrations'")
Analyzed-by: Hui Tang <tanghui20@huawei.com>
Analyzed-by: Zhang Qiao <zhangqiao22@huawei.com>
Signed-off-by: Zicheng Qu <quzicheng@huawei.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260424071113.1199600-1-quzicheng@huawei.com
Similar to how pick_next_entity() must dequeue delayed entities, so too must
wakeup_preempt_fair(). Any delayed task being found means it is eligible and
hence past the 0-lag point, ready for removal.
Worse, by not removing delayed entities from consideration, it can skew the
preemption decision, with the end result that a short slice wakeup will not
result in a preemption.
tip/sched/core tip/sched/core +this patch
cyclictest slice (ms) (default)2.8 8 8
hackbench slice (ms) (default)2.8 20 20
Total Samples | 22559 22595 22683
Average (us) | 157 64( 59%) 59( 8%)
Median (P50) (us) | 57 57( 0%) 58(- 2%)
90th Percentile (us) | 64 60( 6%) 60( 0%)
99th Percentile (us) | 2407 67( 97%) 67( 0%)
99.9th Percentile (us) | 3400 2288( 33%) 727( 68%)
Maximum (us) | 5037 9252(-84%) 7461( 19%)
Fixes: f12e148892 ("sched/fair: Prepare pick_next_task() for delayed dequeue")
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260422093400.319251-1-vincent.guittot@linaro.org
Vincent reported that my rework of his original patch lost a little
something.
Specifically it got the return value wrong; it should not compare
against the old se->vlag, but rather against the current value. Since
the thing that matters is if the effective vruntime of an entity is
affected and the thing needs repositioning or not.
Fixes: 059258b0d4 ("sched/fair: Prevent negative lag increase during delayed dequeue")
Reported-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://patch.msgid.link/20260423094107.GT3102624%40noisy.programming.kicks-ass.net
- Fix UAF race in psi pressure_write() against cgroup file release by
extending cgroup_mutex coverage and ordering of->priv access after
cgroup_kn_lock_live().
- Fix integer overflow in rdmacg_try_charge() when usage equals INT_MAX
by performing the increment in s64.
- Fix asymmetric DL bandwidth accounting on cpuset attach rollback by
recording the CPU used by dl_bw_alloc() so cancel_attach() returns
the reservation to the same root domain.
- Fix nr_dying_subsys_* race that briefly showed 0 in cgroup.stat after
rmdir by incrementing from kill_css() instead of offline_css().
- Typo fix in cgroup-v2 documentation.
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Merge tag 'cgroup-for-7.1-rc1-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup
Pull cgroup fixes from Tejun Heo:
- Fix UAF race in psi pressure_write() against cgroup file release by
extending cgroup_mutex coverage and ordering of->priv access after
cgroup_kn_lock_live()
- Fix integer overflow in rdmacg_try_charge() when usage equals INT_MAX
by performing the increment in s64
- Fix asymmetric DL bandwidth accounting on cpuset attach rollback by
recording the CPU used by dl_bw_alloc() so cancel_attach() returns
the reservation to the same root domain
- Fix nr_dying_subsys_* race that briefly showed 0 in cgroup.stat after
rmdir by incrementing from kill_css() instead of offline_css()
- Typo fix in cgroup-v2 documentation
* tag 'cgroup-for-7.1-rc1-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
docs: cgroup: fix typo 'protetion' -> 'protection'
cgroup: Increment nr_dying_subsys_* from rmdir context
cgroup/cpuset: record DL BW alloc CPU for attach rollback
cgroup/rdma: fix integer overflow in rdmacg_try_charge()
sched/psi: fix race between file release and pressure write
The WARN_ON call in bpf_trampoline_update could never hit, because we
direct the code path with (total == 0) to out label, which effectively
skips the WARN_ON call.
The WARN_ON made sense back then when it checked tr->selector, but now
with total being set just inside the function it's useless.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: Song Liu <song@kernel.org>
Link: https://lore.kernel.org/r/20260424153905.354922-2-jolsa@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
states.c:range_within() must be updated to properly check if
cnum-based range in an old state is a superset of a range in the cur
state. Currently it makes the decision using min/max accessors:
reg_umin(old) <= reg_umin(cur) <= reg_umax(old)
This is wrong for cnums that cross both UT_MAX/0 and ST_MAX/ST_MIN
boundaries. Consider cnum32{base=0x7FFFFFF0, size=0x80000020},
which represents values [0x7FFFFFF0, ..., U32_MAX, 0, ..., 0x10].
Its projections are u32_min/max=0/U32_MAX, s32_min/max=S32_MIN/MAX.
A register with range [0x100, 0x200] (which lies entirely in the gap
of the wrapping range) would pass the min/max check despite having no
overlap with the actual cnum arc.
This commit replaces min/max comparison with cnum{32,64}_is_subset()
operation. The operation implementation is verified using cbmc model
checker in [1].
[1] https://github.com/eddyz87/cnum-verif/
Fixes: bbc6310855 ("bpf: replace min/max fields with struct cnum{32,64}")
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20260425-cnum-range-within-v1-1-2fdca70cb09d@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Fix two error handling issues in kho_add_subtree(), where it doesn't
handle the error path correctly.
1. If fdt_setprop() fails after the subnode has been created, the
subnode is not removed. This leaves an incomplete node in the FDT
(missing "preserved-data" or "blob-size" properties).
2. The fdt_setprop() return value (an FDT error code) is stored
directly in err and returned to the caller, which expects -errno.
Fix both by storing fdt_setprop() results in fdt_err, jumping to a new
out_del_node label that removes the subnode on failure, and only setting
err = 0 on the success path, otherwise returning -ENOMEM (instead of
FDT_ERR_ errors that would come from fdt_setprop).
No user-visible changes. This patch fixes error handling in the KHO
(Kexec HandOver) subsystem, which is used to preserve data across kexec
reboots. The fix only affects a rare failure path during kexec
preparation — specifically when the kernel runs out of space in the
Flattened Device Tree buffer while registering preserved memory regions.
In the unlikely event that this error path was triggered, the old code
would leave a malformed node in the device tree and return an incorrect
error code to the calling subsystem, which could lead to confusing log
messages or incorrect recovery decisions. With this fix, the incomplete
node is properly cleaned up and the appropriate errno value is propagated,
this error code is not returned to the user.
Link: https://lore.kernel.org/20260410-kho_fix_send-v2-1-1b4debf7ee08@debian.org
Fixes: 3dc92c3114 ("kexec: add Kexec HandOver (KHO) generation helpers")
Signed-off-by: Breno Leitao <leitao@debian.org>
Suggested-by: Pratyush Yadav <pratyush@kernel.org>
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Reviewed-by: Pratyush Yadav <pratyush@kernel.org>
Cc: Alexander Graf <graf@amazon.com>
Cc: Breno Leitao <leitao@debian.org>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
When session allocation fails during deserialization, the global 'err'
variable was not updated before returning. This caused subsequent calls
to luo_session_deserialize() to incorrectly report success.
Ensure 'err' is set to the error code from PTR_ERR(session). This ensures
that an error is correctly returned to userspace when it attempts to open
/dev/liveupdate in the new kernel if deserialization failed.
Link: https://lore.kernel.org/20260415193738.515491-1-pasha.tatashin@soleen.com
Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Reviewed-by: Pratyush Yadav (Google) <pratyush@kernel.org>
Cc: David Matlack <dmatlack@google.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Samiullah Khawaja <skhawaja@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
In C, bitfields are not necessarily safe to modify from multiple
threads without locking. Switch "offline" and "offline_disabled" over
to the "flags" field so modifications are safe.
Cc: Rafael J. Wysocki <rafael@kernel.org>
Acked-by: Mark Brown <broonie@kernel.org>
Reviewed-by: Rafael J. Wysocki (Intel) <rafael@kernel.org>
Reviewed-by: Danilo Krummrich <dakr@kernel.org>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Link: https://patch.msgid.link/20260406162231.v5.9.I897d478b4a9361d79cd5073207c1062fd4d0d0e4@changeid
Signed-off-by: Danilo Krummrich <dakr@kernel.org>
In C, bitfields are not necessarily safe to modify from multiple
threads without locking. Switch "dma_ops_bypass" over to the "flags"
field so modifications are safe.
Cc: Christoph Hellwig <hch@lst.de>
Cc: Alexey Kardashevskiy <aik@ozlabs.ru>
Reviewed-by: Rafael J. Wysocki (Intel) <rafael@kernel.org>
Reviewed-by: Danilo Krummrich <dakr@kernel.org>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Link: https://patch.msgid.link/20260406162231.v5.5.If62b84471ef2c85e7ad250f0468867d6dba965ab@changeid
Signed-off-by: Danilo Krummrich <dakr@kernel.org>
In C, bitfields are not necessarily safe to modify from multiple
threads without locking. Switch "dma_skip_sync" over to the "flags"
field so modifications are safe.
Cc: Alexander Lobakin <aleksander.lobakin@intel.com>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Christoph Hellwig <hch@lst.de>
Reviewed-by: Rafael J. Wysocki (Intel) <rafael@kernel.org>
Reviewed-by: Danilo Krummrich <dakr@kernel.org>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Link: https://patch.msgid.link/20260406162231.v5.4.Icf072aa4184dd86a88fa8ca195b09d1651984000@changeid
Signed-off-by: Danilo Krummrich <dakr@kernel.org>
Replace eight independent s64, u64, s32, u32 min/max fields in
bpf_reg_state with two circular number fields:
- cnum64 for a unified signed/unsigned 64-bit range tracking;
- cnum32 for a unified signed/unsigned 32-bit range tracking.
Each cnum represents a range as a single arc on the circular number
line (base + size), from which signed and unsigned bounds are derived
on demand via accessor functions introduced in the preceding commit.
Notable changes:
- Signed<->unsigned deductions in __reg_deduce_bounds() are removed.
- 64<->32 bit deductions are replaced with:
- reg->r32 = cnum32_intersect(reg->r32, cnum32_from_cnum64(reg->r64));
this is functionally equivalent to the old code.
- reg->r64 = cnum64_cnum32_intersect(reg->r64, reg->r32);
this handles a few additional cases, see commit message for
"bpf: representation and basic operations on circular numbers".
- regs_refine_cond_op() now computes results in terms of operations on
sets, e.g. for JNE:
/* Complement of the range [val, val] as cnum64. */
lo = (struct cnum64){ val + 1, U64_MAX - 1 };
reg1->r64 = cnum64_intersect(reg1->r64, lo);
- For add, sub operations on scalars replace explicit bounds
computations with cnum{32,64}_{add,negate}.
- For add, sub operations on pointers deduplicate with arithmetic
operations on scalars and use cnum{32,64}_{add,negate}.
- For and, or, xor operations on scalars remove explicit signed bounds
computations.
- range_bounds_violation() reduces to checking cnum_is_empty().
- const_tnum_range_mismatch() reduces to checking cnum_is_const().
Selftest adjustments: a few existing tests are updated because a
single cnum arc cannot always represent what the old system expressed
as the intersection of independent signed and unsigned ranges.
For example, if the old system tracked u64=[0, U64_MAX-U32_MAX+2] and
s64=[S64_MIN+2, 2] independently, their intersection is a tight
two-point set. A single cnum must pick the shorter arc, losing the
other constraint. These cases are documented with comments in the
adjusted tests.
reg_bounds.c is updated with logic similar to
cnum64_cnum32_intersect(). Instead of using cnums it inspects
intersection between 'b' and first / last / next-after-first /
previous-before-last sub-ranges of 'a'.
reg_bounds.c is also updated to skip test cases that rely
in signed and unsigned ranges intersecting in two intervals,
as such cases are not representable by a single cnum.
The following "crafted" test cases are affected:
- reg_bounds_crafted/(s64)[0xffffffffffff8000; 0x7fff] (u32)<op> [0; 0x1f]
- reg_bounds_crafted/(s64)[0; 0x1f] (u32)<op> [0xffffffffffffff80; 0x7f]
- reg_bounds_crafted/(s64)[0xffffffffffffff80; 0x7f] (u32)<op> [0; 0x1f]
- reg_bounds_crafted/(u64)[0; 1] (s32)<op> [1; 2147483648]
- reg_bounds_crafted/(u64)[1; 2147483648] (s32)<op> [0; 1]
- reg_bounds_crafted/(u64)[0; 0xffffffff00000000] (s64)<op> 0
- reg_bounds_crafted/(u64)0 (s64)<op> [0; 0xffffffff00000000]
- reg_bounds_crafted/(u64)[0; 0xffffffff00000000] (s32)<op> 0
- reg_bounds_crafted/(u64)0 (s32)<op> [0; 0xffffffff00000000]
- reg_bounds_crafted/(s64)[S64_MIN; 0] (u64)<op> S64_MIN
- reg_bounds_crafted/(s64)S64_MIN (u64)<op> [S64_MIN; 0]
- reg_bounds_crafted/(s32)[S32_MIN; 0] (u32)<op> S32_MIN
- reg_bounds_crafted/(s32)S32_MIN (u32)<op> [S32_MIN; 0]
- reg_bounds_crafted/(s64)[0; 0x1f] (u32)<op> [0xffffffff80000000; 0x7fffffff]
- reg_bounds_crafted/(s64)[0xffffffff80000000; 0x7fffffff] (u32)<op> [0; 0x1f]
- reg_bounds_crafted/(s64)[0; 0x1f] (u32)<op> [0xffffffffffff8000; 0x7fff]
As well as some reg_bounds_roand_{consts,ranges}_A_B, where A and B
differ in sign domain.
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20260424-cnums-everywhere-rfc-v1-v3-3-ca434b39a486@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Replace direct access to bpf_reg_state->{smin,smax,umin,umax,
s32_min,s32_max,u32_min,u32_max}_value with getter/setter inline
functions, preparing for future switch to cnum-based internal
representation.
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20260424-cnums-everywhere-rfc-v1-v3-2-ca434b39a486@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit adds basic definitions for cnum32/cnum64.
This is a unified numeric range representation for signed and unsigned
domains. Inspired by an old post from Shung-Hsi Yu [1] and paper [2].
Operations correctness is verified using cbmc model checker,
tests source code can be found in a separate repo [3].
The cnum64_cnum32_intersect() function is notable, because it handled
several cases verifier.c:deduce_bounds_64_from_32() does not.
Given:
- a is a 64-bit range
- b is a 32-bit range
- t is a refined 64-bit range, such that ∀ v ∈ a, (u32)v ∈ b: v ∈ t.
cnum64_cnum32_intersect() makes the following deductions:
(A): 'b' is a sub-range of the first or the last 32-bit
sub-range of 'a':
64-bit number axis --->
N*2^32 (N+1)*2^32 (N+2)*2^32 (N+3)*2^32
||------|---|=====|-------||----------|=====|-------||----------|=====|----|--||
| |< b >| |< b >| |< b >| |
| | | |
|<--+--------------------------- a ---------------------------+--->|
| |
|<-------------------------- t -------------------------->|
(B) 'b' does not intersect with the first of the last 32-bit
sub-range of 'a':
N*2^32 (N+1)*2^32 (N+2)*2^32 (N+3)*2^32
||--|=====|----|----------||--|=====|---------------||--|=====|------------|--||
|< b >| | |< b >| |< b >| |
| | | |
|<-------------+--------- a -------------------|----------->|
| |
|<-------- t ------------------>|
(C) 'b' crosses 0/U32_MAX boundary:
N*2^32 (N+1)*2^32 (N+2)*2^32 (N+3)*2^32
||===|---------|------|===||===|----------------|===||===|---------|------|===||
|b >| | |< b||b >| |< b||b >| | |< b|
| | | |
|<-----+----------------- a --------------+-------->|
| |
|<---------------- t ------------->|
Current implementation of deduce_bounds_64_from_32() only handles
case (A).
[1] https://lore.kernel.org/all/ZTZxoDJJbX9mrQ9w@u94a/
[2] https://jorgenavas.github.io/papers/ACM-TOPLAS-wrapped.pdf
[3] https://github.com/eddyz87/cnum-verif/tree/master
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20260424-cnums-everywhere-rfc-v1-v3-1-ca434b39a486@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Pull to receive:
c0e8ddc76d ("sched_ext: Align cgroup #ifdef guards with SUB_SCHED vs GROUP_SCHED")
which conflicts with:
41e3312861 ("sched_ext: add p->scx.tid and SCX_OPS_TID_TO_TASK lookup")
It's a simple context conflict. Take changes from both.
Signed-off-by: Tejun Heo <tj@kernel.org>
scx_root_enable_workfn() takes cpus_read_lock() before
scx_link_sched(sch), but the `if (ret) goto err_disable` on failure
skips the matching cpus_read_unlock() - all other err_disable gotos
along this path drop the lock first.
scx_link_sched() only returns non-zero on the sub-sched path
(parent != NULL), so the leak path is unreachable via the root
caller today. Still, the unwind is out of line with the surrounding
paths.
Drop cpus_read_lock() before goto err_disable.
v2: Correct Fixes: tag (Andrea Righi).
Fixes: 25037af712 ("sched_ext: Add rhashtable lookup for sub-schedulers")
Reported-by: Chris Mason <clm@meta.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
scx_prog_sched(aux) returns NULL for TRACING / SYSCALL BPF progs that
have no struct_ops association when the root scheduler has sub_attach
set. scx_bpf_task_set_slice() and scx_bpf_task_set_dsq_vtime() pass
that NULL into scx_task_on_sched(sch, p), which under
CONFIG_EXT_SUB_SCHED is rcu_access_pointer(p->scx.sched) == sch. For
any non-scx task p->scx.sched is NULL, so NULL == NULL returns true
and the authority gate is bypassed - a privileged but
non-struct_ops-associated prog can poke p->scx.slice /
p->scx.dsq_vtime on arbitrary tasks.
Reject !sch up front so the gate only admits callers with a resolved
scheduler.
Fixes: 245d09c594 ("sched_ext: Enforce scheduler ownership when updating slice and dsq_vtime")
Reported-by: Chris Mason <clm@meta.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Andrea Righi <arighi@nvidia.com>
select_cpu_from_kfunc() skipped pi_lock for @p when called from
ops.select_cpu() or another rq-locked SCX op, assuming the held lock
protects @p. scx_bpf_select_cpu_dfl() / __scx_bpf_select_cpu_and() accept an
arbitrary KF_RCU task_struct, so a caller in e.g. ops.select_cpu(p1) or
ops.enqueue(p1) can pass some other p2 - the held pi_lock / rq lock is p1's,
not p2's - and reading p2->cpus_ptr / nr_cpus_allowed races with
set_cpus_allowed_ptr() and migrate_disable_switch() on another CPU.
Abort the scheduler on cross-task calls in both branches: for
ops.select_cpu() use scx_kf_arg_task_ok() to verify @p is the wake-up
task recorded in current->scx.kf_tasks[] by SCX_CALL_OP_TASK_RET();
for other rq-locked SCX ops compare task_rq(p) against scx_locked_rq().
v2: Switch the in_select_cpu cross-task check from direct_dispatch_task
comparison to scx_kf_arg_task_ok(). The former spuriously rejects when
ops.select_cpu() calls scx_bpf_dsq_insert() first, then calls
scx_bpf_select_cpu_*() on the same task. (Andrea Righi)
Fixes: 0022b32850 ("sched_ext: Decouple kfunc unlocked-context check from kf_mask")
Reported-by: Chris Mason <clm@meta.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Andrea Righi <arighi@nvidia.com>
Two EXT_GROUP_SCHED/SUB_SCHED guards are misclassified:
- scx_root_enable_workfn()'s cgroup_get(cgrp) and the err_put_cgrp unwind
in scx_alloc_and_add_sched() are under `#if GROUP || SUB`, but the
matching cgroup_put() in scx_sched_free_rcu_work() is inside `#ifdef SUB`
only (via sch->cgrp, stored only under SUB). GROUP-only would leak a
reference on every root-sched enable.
- sch_cgroup() / set_cgroup_sched() live under `#if GROUP || SUB` but touch
SUB-only fields (sch->cgrp, cgroup->scx_sched). GROUP-only wouldn't
compile.
GROUP needs CGROUP_SCHED; SUB needs only CGROUPS. CGROUPS=y/CGROUP_SCHED=n
gives the reachable GROUP=n, SUB=y combination; GROUP=y, SUB=n isn't
reachable today (SUB is def_bool y under CGROUPS). Neither miscategorization
triggers a real bug in any reachable config, but keep the guards honest:
- Narrow cgroup_get and err_put_cgrp to `#ifdef SUB` (matches the free-side
put).
- Move sch_cgroup() and set_cgroup_sched() to a separate `#ifdef SUB` block
with no-op stubs for the !SUB case; keep root_cgroup() and scx_cgroup_{
lock,unlock}() under `#if GROUP || SUB` since those only need cgroup core.
Fixes: ebeca1f930 ("sched_ext: Introduce cgroup sub-sched support")
Reported-by: Chris Mason <clm@meta.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Andrea Righi <arighi@nvidia.com>
scx_bypass_lb_{donee,resched}_cpumask were file-scope statics shared by all
scheduler instances. With CONFIG_EXT_SUB_SCHED, multiple sched instances
each arm their own bypass_lb_timer; concurrent bypass_lb_node() calls RMW
the global cpumasks with no lock, corrupting donee/resched decisions.
Move the cpumasks into struct scx_sched, allocate them alongside the timer
in scx_alloc_and_add_sched(), free them in scx_sched_free_rcu_work().
Fixes: 95d1df610c ("sched_ext: Implement load balancer for bypass mode")
Cc: stable@vger.kernel.org # v6.19+
Reported-by: Chris Mason <clm@meta.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Andrea Righi <arighi@nvidia.com>
scx_prio_less() runs from core-sched's pick_next_task() path with rq
locked but invokes ops.core_sched_before() with NULL locked_rq, leaving
scx_locked_rq_state NULL. If the BPF callback calls a kfunc that
re-acquires rq based on scx_locked_rq() - e.g. scx_bpf_cpuperf_set(cpu)
- it re-acquires the already-held rq.
Pass task_rq(a).
Fixes: 7b0888b7cc ("sched_ext: Implement core-sched support")
Cc: stable@vger.kernel.org # v6.12+
Reported-by: Chris Mason <clm@meta.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Andrea Righi <arighi@nvidia.com>
scx_dump_state() walks CPUs with rq_lock_irqsave() held and invokes
ops.dump_cpu / ops.dump_task with NULL locked_rq, leaving
scx_locked_rq_state NULL. If the BPF callback calls a kfunc that
re-acquires rq based on scx_locked_rq() - e.g. scx_bpf_cpuperf_set(cpu)
- it re-acquires the already-held rq.
Pass the held rq to SCX_CALL_OP(). Thread it into scx_dump_task() too.
The pre-loop ops.dump call runs before rq_lock_irqsave() so keeps
rq=NULL.
Fixes: 07814a9439 ("sched_ext: Print debug dump after an error exit")
Cc: stable@vger.kernel.org # v6.12+
Reported-by: Chris Mason <clm@meta.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Andrea Righi <arighi@nvidia.com>
SCX_CALL_OP{,_RET}() unconditionally clears scx_locked_rq_state to NULL on
exit. Correct at the top level, but ops can recurse via
scx_bpf_sub_dispatch(): a parent's ops.dispatch calls the helper, which
invokes the child's ops.dispatch under another SCX_CALL_OP. When the inner
call returns, the NULL clobbers the outer's state. The parent's BPF then
calls kfuncs like scx_bpf_cpuperf_set() which read scx_locked_rq()==NULL and
re-acquire the already-held rq.
Snapshot scx_locked_rq_state on entry and restore on exit. Rename the rq
parameter to locked_rq across all SCX_CALL_OP* macros so the snapshot local
can be typed as 'struct rq *' without colliding with the parameter token in
the expansion. SCX_CALL_OP_TASK{,_RET}() and SCX_CALL_OP_2TASKS_RET() funnel
through the two base macros and inherit the fix.
Fixes: 4f8b122848 ("sched_ext: Add basic building blocks for nested sub-scheduler dispatching")
Reported-by: Chris Mason <clm@meta.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Andrea Righi <arighi@nvidia.com>
dispatch_enqueue()'s FIFO-tail path used list_empty(&dsq->list) to decide
whether to set dsq->first_task on enqueue. dsq->list can contain parked BPF
iterator cursors (SCX_DSQ_LNODE_ITER_CURSOR), so list_empty() is not a
reliable "no real task" check. If the last real task is unlinked while a
cursor is parked, first_task becomes NULL; the next FIFO-tail enqueue then
sees list_empty() == false and skips the first_task update, leaving
scx_bpf_dsq_peek() returning NULL for a non-empty DSQ.
Test dsq->first_task directly, which already tracks only real tasks and is
maintained under dsq->lock.
Fixes: 44f5c8ec5b ("sched_ext: Add lockless peek operation for DSQs")
Cc: stable@vger.kernel.org # v6.19+
Reported-by: Chris Mason <clm@meta.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Andrea Righi <arighi@nvidia.com>
Cc: Ryan Newton <newton@meta.com>
scx_bpf_create_dsq() resolves the calling scheduler via scx_prog_sched(aux)
and inserts the new DSQ into that scheduler's dsq_hash. Its inverse
scx_bpf_destroy_dsq() and the query helper scx_bpf_dsq_nr_queued() were
hard-coded to rcu_dereference(scx_root), so a sub-scheduler could only
destroy or query DSQs in the root scheduler's hash - never its own. If the
root had a DSQ with the same id, the sub-sched silently destroyed it and the
root aborted on the next dispatch ("invalid DSQ ID 0x0..").
Take a const struct bpf_prog_aux *aux via KF_IMPLICIT_ARGS and resolve the
scheduler with scx_prog_sched(aux), matching scx_bpf_create_dsq().
Fixes: ebeca1f930 ("sched_ext: Introduce cgroup sub-sched support")
Reported-by: Chris Mason <clm@meta.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Andrea Righi <arighi@nvidia.com>
scx_group_set_{weight,idle,bandwidth}() cache scx_root before acquiring
scx_cgroup_ops_rwsem, so the pointer can be stale by the time the op runs.
If the loaded scheduler is disabled and freed (via RCU work) and another is
enabled between the naked load and the rwsem acquire, the reader sees
scx_cgroup_enabled=true (the new scheduler's) but dereferences the freed one
- UAF on SCX_HAS_OP(sch, ...) / SCX_CALL_OP(sch, ...).
scx_cgroup_enabled is toggled only under scx_cgroup_ops_rwsem write
(scx_cgroup_{init,exit}), so reading scx_root inside the rwsem read section
correlates @sch with the enabled snapshot.
Fixes: a5bd6ba30b ("sched_ext: Use cgroup_lock/unlock() to synchronize against cgroup operations")
Cc: stable@vger.kernel.org # v6.18+
Reported-by: Chris Mason <clm@meta.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Andrea Righi <arighi@nvidia.com>
scx_sub_enable_workfn()'s prep loop calls __scx_init_task(sch, p, false)
without transitioning task state, then sets SCX_TASK_SUB_INIT. If prep fails
partway, the abort path runs __scx_disable_and_exit_task(sch, p) on the
marked tasks. Task state is still the parent's ENABLED, so that dispatches
to the SCX_TASK_ENABLED arm and calls scx_disable_task(sch, p) - i.e.
child->ops.disable() - for tasks on which child->ops.enable() never ran. A
BPF sub-scheduler allocating per-task state in enable/freeing in disable
would operate on uninitialized state.
The dying-task branch in scx_disable_and_exit_task() has the same problem,
and scx_enabling_sub_sched was cleared before the abort cleanup loop - a
task exiting during cleanup tripped the WARN and skipped both ops.exit_task
and the SCX_TASK_SUB_INIT clear, leaking per-task resources and leaving the
task stuck.
Introduce scx_sub_init_cancel_task() that calls ops.exit_task with
cancelled=true - matching what the top-level init path does when init_task
itself returns -errno. Use it in the abort loop and in the dying-task
branch. scx_enabling_sub_sched now stays set until the abort loop finishes
clearing SUB_INIT, so concurrent exits hitting the dying-task branch can
still find @sch. That branch also clears SCX_TASK_SUB_INIT unconditionally
when seen, leaving the task unmarked even if the WARN fires.
Fixes: 337ec00b1d ("sched_ext: Implement cgroup sub-sched enabling and disabling")
Reported-by: Chris Mason <clm@meta.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Andrea Righi <arighi@nvidia.com>
bypass_lb_cpu() transfers tasks between per-CPU bypass DSQs without
migrating them - task_cpu() only updates when the donee later consumes the
task via move_remote_task_to_local_dsq(). If the LB timer fires again before
consumption and the new DSQ becomes a donor, @p is still on the previous CPU
and task_rq(@p) != donor_rq. @p can't be moved without its own rq locked.
Skip such tasks.
Fixes: 95d1df610c ("sched_ext: Implement load balancer for bypass mode")
Cc: stable@vger.kernel.org # v6.19+
Reported-by: Chris Mason <clm@meta.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Andrea Righi <arighi@nvidia.com>
bpf_iter_scx_dsq_new() clears kit->dsq on failure and
bpf_iter_scx_dsq_{next,destroy}() guard against that. scx_dsq_move() doesn't -
it dereferences kit->dsq immediately, so a BPF program that calls
scx_bpf_dsq_move[_vtime]() after a failed iter_new oopses the kernel.
Return false if kit->dsq is NULL.
Fixes: 4c30f5ce4f ("sched_ext: Implement scx_bpf_dispatch[_vtime]_from_dsq()")
Cc: stable@vger.kernel.org # v6.12+
Reported-by: Chris Mason <clm@meta.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Andrea Righi <arighi@nvidia.com>
When ops.sub_attach is set, scx_alloc_and_add_sched() creates sub_kset as a
child of &sch->kobj, which pins the parent with its own reference. The
disable paths never call kset_unregister(), so the final kobject_put() in
bpf_scx_unreg() leaves a stale reference and scx_kobj_release() never runs,
leaking the whole struct scx_sched on every load/unload cycle.
Unregister sub_kset in scx_root_disable() and scx_sub_disable() before
kobject_del(&sch->kobj).
Fixes: ebeca1f930 ("sched_ext: Introduce cgroup sub-sched support")
Reported-by: Chris Mason <clm@meta.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Andrea Righi <arighi@nvidia.com>
scx_hardlockup() runs from NMI and eventually calls scx_claim_exit(),
which takes scx_sched_lock. scx_sched_lock isn't NMI-safe and grabbing
it from NMI context can lead to deadlocks.
The hardlockup handler is best-effort recovery and the disable path it
triggers runs off of irq_work anyway. Move the handle_lockup() call into
an irq_work so it runs in IRQ context.
Fixes: ebeca1f930 ("sched_ext: Introduce cgroup sub-sched support")
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Andrea Righi <arighi@nvidia.com>
- Fix accounting of persistent ring buffer rewind
On boot up, the head page is moved back to the earliest point of
the saved ring buffer. This is because the ring buffer being read by
user space on a crash may not save the part it read. Rewinding the head
page back to the earliest saved position helps keep those events from
being lost.
The number of events is also read during boot up and displayed in the
stats file in the tracefs directory. It's also used for other accounting
as well. On boot up, the "reader page" is accounted for but a rewind may
put it back into the buffer and then the reader page may be accounted
for again.
Save off the original reader page and skip accounting it when scanning
the pages in the ring buffer.
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Merge tag 'trace-ring-buffer-v7.1-3' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace
Pull ring-buffer fix from Steven Rostedt:
- Fix accounting of persistent ring buffer rewind
On boot up, the head page is moved back to the earliest point of the
saved ring buffer. This is because the ring buffer being read by user
space on a crash may not save the part it read. Rewinding the head
page back to the earliest saved position helps keep those events from
being lost.
The number of events is also read during boot up and displayed in the
stats file in the tracefs directory. It's also used for other
accounting as well. On boot up, the "reader page" is accounted for
but a rewind may put it back into the buffer and then the reader page
may be accounted for again.
Save off the original reader page and skip accounting it when
scanning the pages in the ring buffer.
* tag 'trace-ring-buffer-v7.1-3' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
ring-buffer: Do not double count the reader_page
Since the cpu_buffer->reader_page is updated if there are unwound
pages. After that update, we should skip the page if it is the
original reader_page, because the original reader_page is already
checked.
Cc: stable@vger.kernel.org
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Ian Rogers <irogers@google.com>
Link: https://patch.msgid.link/177701353063.2223789.1471163147644103306.stgit@mhiramat.tok.corp.google.com
Fixes: ca296d32ec ("tracing: ring_buffer: Rewind persistent ring buffer on reboot")
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
When unregistered my self-written scx scheduler, the following panic
occurs.
[ 229.923133] Kernel text patching generated an invalid instruction at 0xffff80009bc2c1f8!
[ 229.923146] Internal error: Oops - BRK: 00000000f2000100 [#1] SMP
[ 230.077871] CPU: 48 UID: 0 PID: 1760 Comm: kworker/u583:7 Not tainted 7.0.0+ #3 PREEMPT(full)
[ 230.086677] Hardware name: NVIDIA GB200 NVL/P3809-BMC, BIOS 02.05.12 20251107
[ 230.093972] Workqueue: events_unbound bpf_map_free_deferred
[ 230.099675] Sched_ext: invariant_0.1.0_aarch64_unknown_linux_gnu_debug (disabling), task: runnable_at=-174ms
[ 230.116843] pc : 0xffff80009bc2c1f8
[ 230.120406] lr : dequeue_task_scx+0x270/0x2d0
[ 230.217749] Call trace:
[ 230.228515] 0xffff80009bc2c1f8 (P)
[ 230.232077] dequeue_task+0x84/0x188
[ 230.235728] sched_change_begin+0x1dc/0x250
[ 230.240000] __set_cpus_allowed_ptr_locked+0x17c/0x240
[ 230.245250] __set_cpus_allowed_ptr+0x74/0xf0
[ 230.249701] ___migrate_enable+0x4c/0xa0
[ 230.253707] bpf_map_free_deferred+0x1a4/0x1b0
[ 230.258246] process_one_work+0x184/0x540
[ 230.262342] worker_thread+0x19c/0x348
[ 230.266170] kthread+0x13c/0x150
[ 230.269465] ret_from_fork+0x10/0x20
[ 230.281393] Code: d4202000 d4202000 d4202000 d4202000 (d4202000)
[ 230.287621] ---[ end trace 0000000000000000 ]---
[ 231.160046] Kernel panic - not syncing: Oops - BRK: Fatal exception in interrupt
The root cause is that the JIT page backing ops->quiescent() is freed
before all callers of that function have stopped.
The expected ordering during teardown is:
bitmap_zero(sch->has_op) + synchronize_rcu()
-> guarantees no CPU will ever call sch->ops.* again
-> only THEN free the BPF struct_ops JIT page
bpf_scx_unreg() is supposed to enforce the order, but after
commit f4a6c506d1 ("sched_ext: Always bounce scx_disable() through
irq_work"), disable_work is no longer queued directly, causing
kthread_flush_work() to be a noop. Thus, the caller drops the struct_ops
map too early and poisoned with AARCH64_BREAK_FAULT before
disable_workfn ever execute.
So the subsequent dequeue_task() still sees SCX_HAS_OP(sch, quiescent)
as true and calls ops.quiescent, which hit on the poisoned page and BRK
panic.
Add a helper scx_flush_disable_work() so the future use cases that want
to flush disable_work can use it.
Also amend the call for scx_root_enable_workfn() and
scx_sub_enable_workfn() which have similar pattern in the error path.
Fixes: f4a6c506d1 ("sched_ext: Always bounce scx_disable() through irq_work")
Signed-off-by: Richard Cheng <icheng@nvidia.com>
Reviewed-by: Andrea Righi <arighi@nvidia.com>
Reviewed-by: Cheng-Yang Chou <yphbchou0911@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Incrementing nr_dying_subsys_* in offline_css(), which is executed by
cgroup_offline_wq worker, leads to a race where user can see the value
to be 0 if he reads cgroup.stat after calling rmdir and before the worker
executes. This makes the user wrongly expect resources released by the
removed cgroup to be available for a new assignment.
Increment nr_dying_subsys_* from kill_css(), which is called from the
cgroup_rmdir() context.
Fixes: ab03125268 ("cgroup: Show # of subsystem CSSes in cgroup.stat")
Signed-off-by: Petr Malat <oss@malat.biz>
Signed-off-by: Tejun Heo <tj@kernel.org>
Replace the hand-rolled strsep/strcmp/match_string parsing in
rdmacg_resource_set_max() with a match_table_t and match_token()
pattern, following the convention used by user_proactive_reclaim()
and ioc_cost_model_write().
The old strncmp(value, RDMACG_MAX_STR, strlen(value)) also had two
bugs that are fixed by this refactor:
- It matched "ma" as "max" because strncmp only compared the
shorter strlen(value) bytes.
- It silently accepted "hca_handle=" (empty value) as "max"
because strncmp with n=0 always returns 0.
The match_token() approach also robustly handles extra whitespace in
the input by splitting on " \t\n" and skipping empty tokens.
Suggested-by: "Michal Koutný" <mkoutny@suse.com>
Signed-off-by: Tao Cui <cuitao@kylinos.cn>
Signed-off-by: Tejun Heo <tj@kernel.org>
local_dsq_post_enq() calls call_task_dequeue() with scx_root instead of
the scheduler instance actually managing the task. When
CONFIG_EXT_SUB_SCHED is enabled, tasks may be managed by a sub-scheduler
whose ops.dequeue() callback differs from root's. Using scx_root causes
the wrong scheduler's ops.dequeue() to be consulted: sub-sched tasks
dispatched to a local DSQ via scx_bpf_dsq_move_to_local() will have
SCX_TASK_IN_CUSTODY cleared but the sub-scheduler's ops.dequeue() is
never invoked, violating the custody exit semantics.
Fix by adding a 'struct scx_sched *sch' parameter to local_dsq_post_enq()
and move_local_task_to_local_dsq(), and propagating the correct scheduler
from their callers dispatch_enqueue(), move_task_between_dsqs(), and
consume_dispatch_q().
This is consistent with dispatch_enqueue()'s non-local path which already
passes 'sch' directly to call_task_dequeue() for global/bypass DSQs.
Fixes: ebf1ccff79 ("sched_ext: Fix ops.dequeue() semantics")
Signed-off-by: zhidao su <suzhidao@xiaomi.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Introduce BPF_REG_PARAMS as a dedicated BPF register for stack
argument accesses. It occupies the BPF register number 11 (R11),
which is used as the base pointer for the stack argument area,
keeping it separate from the R10-based (BPF_REG_FP) program stack.
The kernel-internal hidden register BPF_REG_AX previously occupied
slot 11 (MAX_BPF_REG). With BPF_REG_PARAMS taking that slot,
BPF_REG_AX moves to slot 12 and MAX_BPF_EXT_REG increases
accordingly.
Acked-by: Puranjay Mohan <puranjay@kernel.org>
Acked-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20260423033506.2542005-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This change prepares verifier log reporting for upcoming kfunc stack
argument support.
Currently verifier log code mostly assumes that an argument can be
described directly by a register number. That works for arguments
passed in `R1` to `R5`, but it does not work once kfunc arguments
can also be passed on the stack.
Introduce an opaque `argno_t` type that encodes both register-based
and arg-based references. Four helpers form the interface:
- argno_from_reg(regno): create from a register number
- argno_from_arg(arg): create from a 1-based arg number
- reg_from_argno(a): extract register number, or -1
- arg_from_argno(a): extract arg number, or -1
reg_arg_name() converts an argno_t to a human-readable string for
verifier logs: "R%d" for register arguments, or "*(R11-off)" for
stack arguments beyond R5.
Update selftests accordingly.
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20260423033501.2539667-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
To support stack arguments, in later patches, argno will represent
both registers and stack arguments. To avoid confusion, rename
existing argno to arg.
Acked-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20260423033456.2539340-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Similar to the previous patch, try to pass bpf_reg_state from caller
to callee. Both mem_reg and size_reg are passed to helper functions.
This is important for stack arguments as they may be beyond registers 1-5.
Acked-by: Puranjay Mohan <puranjay@kernel.org>
Acked-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20260423033451.2539065-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
In many cases, once a bpf_reg_state is defined, it can pass to
callee's. Otherwise, callee will need to get bpf_reg_state again
based on regno. More importantly, this is needed for later stack
arguments for kfuncs since the register state for stack arguments does
not have a corresponding regno. So it makes sense to pass reg state
for callee's.
The following is the only change to avoid compilation warning:
static int sanitize_check_bounds(struct bpf_verifier_env *env,
const struct bpf_insn *insn,
- const struct bpf_reg_state *dst_reg)
+ struct bpf_reg_state *dst_reg)
Acked-by: Puranjay Mohan <puranjay@kernel.org>
Acked-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Reviewed-by: Amery Hung <ameryhung@gmail.com>
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20260423033446.2538321-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
In check_max_stack_depth_subprog(), the local variable
tail_call_reachable is set when entering a callee that has a tail
call, but never reset when popping back to the parent. This causes
the flag to leak across sibling subprogs in the DFS traversal.
This results in unnecessary JIT overhead: the JIT emits tail call
counter preservation code for subprogs that can never be reached
via a tail call path.
Fix this by resetting tail_call_reachable to the parent's actual
per-subprog flag when popping a frame. If the parent was already
marked tail_call_reachable by a previous sibling's traversal, the
local variable stays true. Otherwise it resets to false, so
subsequent siblings start with a clean state.
Acked-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20260423033435.2538013-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Chaitanya, John and Mikhail reported commit 25500ba7e7 ("locking/mutex:
Remove the list_head from struct mutex") wrecked ww_mutex.
Specifically there were 2 issues:
- __ww_waiter_prev() had the termination condition wrong; it would terminate
when the previous entry was the first, which results in a truncated
iteration: W3, W2, (no W1).
- __mutex_add_waiter(@pos != NULL), as used by __ww_waiter_add() /
__ww_mutex_add_waiter(); this inserts @waiter before @pos (which is what
list_add_tail() does). But this should then also update lock->first_waiter.
Much thanks to Prateek for spotting the __mutex_add_waiter() issue!
Fixes: 25500ba7e7 ("locking/mutex: Remove the list_head from struct mutex")
Reported-by: "Borah, Chaitanya Kumar" <chaitanya.kumar.borah@intel.com>
Closes: https://lore.kernel.org/r/af005996-05e9-4336-8450-d14ca652ba5d%40intel.com
Reported-by: John Stultz <jstultz@google.com>
Closes: https://lore.kernel.org/r/CANDhNCq%3Doizzud3hH3oqGzTrcjB8OwGeineJ3mwZuGdDWG8fRQ%40mail.gmail.com
Reported-by: Mikhail Gavrilov <mikhail.v.gavrilov@gmail.com>
Closes: https://lore.kernel.org/r/CABXGCsO5fKq2nD9nO8yO1z50ZzgCPWqueNXHANjntaswoOh2Dg@mail.gmail.com
Debugged-by: K Prateek Nayak <kprateek.nayak@amd.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: K Prateek Nayak <kprateek.nayak@amd.com>
Tested-by: Mikhail Gavrilov <mikhail.v.gavrilov@gmail.com>
Link: https://patch.msgid.link/20260422092335.GH3102924%40noisy.programming.kicks-ass.net
- Make undefsyms_base.c into a real file
The file undefsyms_base.c is used to catch any symbols used by a remote
ring buffer that is made for use of a pKVM hypervisor. As it doesn't share
the same text as the rest of the kernel, referencing any symbols within
the kernel will make it fail to be built for the standalone hypervisor.
A file was created by the Makefile that checked for any symbols that could
cause issues. There's no reason to have this file created by the Makefile,
just create it as a normal file instead.
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Merge tag 'trace-ring-buffer-v7.1-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace
Pull ring-buffer fix from Steven Rostedt:
- Make undefsyms_base.c into a real file
The file undefsyms_base.c is used to catch any symbols used by a
remote ring buffer that is made for use of a pKVM hypervisor. As it
doesn't share the same text as the rest of the kernel, referencing
any symbols within the kernel will make it fail to be built for the
standalone hypervisor.
A file was created by the Makefile that checked for any symbols that
could cause issues. There's no reason to have this file created by
the Makefile, just create it as a normal file instead.
* tag 'trace-ring-buffer-v7.1-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
tracing: Make undefsyms_base.c a first-class citizen
Only a very small update for kgdb this cycle: a single patch from Kexin Sun
that fixes some outdated comments.
Signed-off-by: Daniel Thompson (RISCstar) <danielt@kernel.org>
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Merge tag 'kgdb-7.1-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/danielt/linux
Pull kgdb update from Daniel Thompson:
"Only a very small update for kgdb this cycle: a single patch from
Kexin Sun that fixes some outdated comments"
* tag 'kgdb-7.1-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/danielt/linux:
kgdb: update outdated references to kgdb_wait()
Allow BPF_PROG_TYPE_RAW_TRACEPOINT, BPF_PROG_TYPE_TRACEPOINT, and
BPF_TRACE_RAW_TP (tp_btf) programs to be sleepable by adding them
to can_be_sleepable().
For BTF-based raw tracepoints (tp_btf), add a load-time check in
bpf_check_attach_target() that rejects sleepable programs attaching
to non-faultable tracepoints with a descriptive error message.
For raw tracepoints (raw_tp), add an attach-time check in
bpf_raw_tp_link_attach() that rejects sleepable programs on
non-faultable tracepoints. The attach-time check is needed because
the tracepoint name is not known at load time for raw_tp.
The attach-time check for classic tracepoints (tp) in
__perf_event_set_bpf_prog() was added in the previous patch.
Replace the verbose error message that enumerates allowed program
types with a generic "Program of this type cannot be sleepable"
message, since the list of sleepable-capable types keeps growing.
Signed-off-by: Mykyta Yatsenko <yatsenko@meta.com>
Acked-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/bpf/20260422-sleepable_tracepoints-v13-4-99005dff21ef@meta.com
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Add trace_call_bpf_faultable(), a variant of trace_call_bpf() for
faultable tracepoints that supports sleepable BPF programs. It uses
rcu_tasks_trace for lifetime protection and
bpf_prog_run_array_sleepable() for per-program RCU flavor selection,
following the uprobe_prog_run() pattern.
Restructure perf_syscall_enter() and perf_syscall_exit() to run BPF
programs before perf event processing. Previously, BPF ran after the
per-cpu perf trace buffer was allocated under preempt_disable,
requiring cleanup via perf_swevent_put_recursion_context() on filter.
Now BPF runs in faultable context before preempt_disable, reading
syscall arguments from local variables instead of the per-cpu trace
record, removing the dependency on buffer allocation. This allows
sleepable BPF programs to execute and avoids unnecessary buffer
allocation when BPF filters the event. The perf event submission
path (buffer allocation, fill, submit) remains under preempt_disable
as before. Since BPF no longer runs within the buffer allocation
context, the fake_regs output parameter to perf_trace_buf_alloc()
is no longer needed and is replaced with NULL.
Add an attach-time check in __perf_event_set_bpf_prog() to reject
sleepable BPF_PROG_TYPE_TRACEPOINT programs on non-syscall
tracepoints, since only syscall tracepoints run in faultable context.
This prepares the classic tracepoint runtime and attach paths for
sleepable programs. The verifier changes to allow loading sleepable
BPF_PROG_TYPE_TRACEPOINT programs are in a subsequent patch.
To: Peter Zijlstra <peterz@infradead.org>
To: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Mykyta Yatsenko <yatsenko@meta.com>
Acked-by: Kumar Kartikeya Dwivedi <memxor@gmail.com> # for BPF bits
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Link: https://lore.kernel.org/bpf/20260422-sleepable_tracepoints-v13-3-99005dff21ef@meta.com
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Rework __bpf_trace_run() to support sleepable BPF programs by using
explicit RCU flavor selection, following the uprobe_prog_run() pattern.
For sleepable programs, use rcu_read_lock_tasks_trace() for lifetime
protection with migrate_disable(). For non-sleepable programs, use the
regular rcu_read_lock_dont_migrate().
Remove the preempt_disable_notrace/preempt_enable_notrace pair from
the faultable tracepoint BPF probe wrapper in bpf_probe.h, since
migration protection and RCU locking are now handled per-program
inside __bpf_trace_run().
Adapt bpf_prog_test_run_raw_tp() for sleepable programs: reject
BPF_F_TEST_RUN_ON_CPU since sleepable programs cannot run in hardirq
or preempt-disabled context, and call __bpf_prog_test_run_raw_tp()
directly instead of via smp_call_function_single(). Rework
__bpf_prog_test_run_raw_tp() to select RCU flavor per-program and
add per-program recursion context guard for private stack safety.
Signed-off-by: Mykyta Yatsenko <yatsenko@meta.com>
Acked-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/bpf/20260422-sleepable_tracepoints-v13-1-99005dff21ef@meta.com
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Fix fprobe to unregister ftrace_ops if corresponding type of fprobe
does not exist on the fprobe_ip_table and it is expected to be empty
when unloading modules.
Since ftrace thinks that the empty hash means everything to be traced,
if we set fprobes only on the unloaded module, all functions are traced
unexpectedly after unloading module.
e.g.
# modprobe xt_LOG.ko
# echo 'f:test log_tg*' > dynamic_events
# echo 1 > events/fprobes/test/enable
# cat enabled_functions
log_tg [xt_LOG] (1) tramp: 0xffffffffa0004000 (fprobe_ftrace_entry+0x0/0x490) ->fprobe_ftrace_entry+0x0/0x490
log_tg_check [xt_LOG] (1) tramp: 0xffffffffa0004000 (fprobe_ftrace_entry+0x0/0x490) ->fprobe_ftrace_entry+0x0/0x490
log_tg_destroy [xt_LOG] (1) tramp: 0xffffffffa0004000 (fprobe_ftrace_entry+0x0/0x490) ->fprobe_ftrace_entry+0x0/0x490
# rmmod xt_LOG
# wc -l enabled_functions
34085 enabled_functions
Link: https://lore.kernel.org/all/177669368776.132053.10042301916765771279.stgit@mhiramat.tok.corp.google.com/
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
The function kgdb_wait() was folded into the static function
kgdb_cpu_enter() by commit 62fae31219 ("kgdb: eliminate
kgdb_wait(), all cpus enter the same way"). Update the four stale
references accordingly:
- include/linux/kgdb.h and arch/x86/kernel/kgdb.c: the
kgdb_roundup_cpus() kdoc describes what other CPUs are rounded up
to call. Because kgdb_cpu_enter() is static, the correct public
entry point is kgdb_handle_exception(); also fix a pre-existing
grammar error ("get them be" -> "get them into") and reflow the
text.
- kernel/debug/debug_core.c: replace with the generic description
"the debug trap handler", since the actual entry path is
architecture-specific.
- kernel/debug/gdbstub.c: kgdb_cpu_enter() is correct here (it
describes internal state, not a call target); add the missing
parentheses.
Suggested-by: Daniel Thompson <daniel@riscstar.com>
Assisted-by: unnamed:deepseek-v3.2 coccinelle
Signed-off-by: Kexin Sun <kexinsun@smail.nju.edu.cn>
Commit 2c67dc457b ("tracing: fprobe: optimization for entry only case")
introduced a different ftrace_ops for entry-only fprobes.
However, when unregistering an fprobe, the kernel only checks if another
fprobe exists at the same address, without checking which type of fprobe
it is.
If different fprobes are registered at the same address, the same address
will be registered in both fgraph_ops and ftrace_ops, but only one of
them will be deleted when unregistering. (the one removed first will not
be deleted from the ops).
This results in junk entries remaining in either fgraph_ops or ftrace_ops.
For example:
=======
cd /sys/kernel/tracing
# 'Add entry and exit events on the same place'
echo 'f:event1 vfs_read' >> dynamic_events
echo 'f:event2 vfs_read%return' >> dynamic_events
# 'Enable both of them'
echo 1 > events/fprobes/enable
cat enabled_functions
vfs_read (2) ->arch_ftrace_ops_list_func+0x0/0x210
# 'Disable and remove exit event'
echo 0 > events/fprobes/event2/enable
echo -:event2 >> dynamic_events
# 'Disable and remove all events'
echo 0 > events/fprobes/enable
echo > dynamic_events
# 'Add another event'
echo 'f:event3 vfs_open%return' > dynamic_events
cat dynamic_events
f:fprobes/event3 vfs_open%return
echo 1 > events/fprobes/enable
cat enabled_functions
vfs_open (1) tramp: 0xffffffffa0001000 (ftrace_graph_func+0x0/0x60) ->ftrace_graph_func+0x0/0x60 subops: {ent:fprobe_fgraph_entry+0x0/0x620 ret:fprobe_return+0x0/0x150}
vfs_read (1) tramp: 0xffffffffa0001000 (ftrace_graph_func+0x0/0x60) ->ftrace_graph_func+0x0/0x60 subops: {ent:fprobe_fgraph_entry+0x0/0x620 ret:fprobe_return+0x0/0x150}
=======
As you can see, an entry for the vfs_read remains.
To fix this issue, when unregistering, the kernel should also check if
there is the same type of fprobes still exist at the same address, and
if not, delete its entry from either fgraph_ops or ftrace_ops.
Link: https://lore.kernel.org/all/177669367993.132053.10553046138528674802.stgit@mhiramat.tok.corp.google.com/
Fixes: 2c67dc457b ("tracing: fprobe: optimization for entry only case")
Cc: stable@vger.kernel.org
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
When register_fprobe_ips() fails, it tries to remove a list of
fprobe_hash_node from fprobe_ip_table, but it missed to remove
fprobe itself from fprobe_table. Moreover, when removing
the fprobe_hash_node which is added to rhltable once, it must
use kfree_rcu() after removing from rhltable.
To fix these issues, this reuses unregister_fprobe() internal
code to rollback the half-way registered fprobe.
Link: https://lore.kernel.org/all/177669366417.132053.17874946321744910456.stgit@mhiramat.tok.corp.google.com/
Fixes: 4346ba1604 ("fprobe: Rewrite fprobe on function-graph tracer")
Cc: stable@vger.kernel.org
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
unregister_fprobe() can fail under memory pressure because of memory
allocation failure, but this maybe called from module unloading, and
usually there is no way to retry it. Moreover. trace_fprobe does not
check the return value.
To fix this problem, unregister fprobe and fprobe_hash_node even if
working memory allocation fails.
Anyway, if the last fprobe is removed, the filter will be freed.
Link: https://lore.kernel.org/all/177669365629.132053.8433032896213721288.stgit@mhiramat.tok.corp.google.com/
Fixes: 4346ba1604 ("fprobe: Rewrite fprobe on function-graph tracer")
Cc: stable@vger.kernel.org
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Reject registration of a registered fprobe which is on the fprobe
hash table before initializing fprobe.
The add_fprobe_hash() checks this re-register fprobe, but since
fprobe_init() clears hlist_array field, it is too late to check it.
It has to check the re-registration before touncing fprobe.
Link: https://lore.kernel.org/all/177669364845.132053.18375367916162315835.stgit@mhiramat.tok.corp.google.com/
Fixes: 4346ba1604 ("fprobe: Rewrite fprobe on function-graph tracer")
Cc: stable@vger.kernel.org
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
BTF maximum vlen is encoded using 16 bits with a maximum vlen
of 65535. This has sufficed for structs, function parameters
and enumerated type values. However, with upcoming BTF location
information - in particular information about inline sites -
this limit is surpassed. Use bits 16-23 - currently unused in
BTF info - to extend to 24 bits, giving a max vlen of (2^24 - 1),
or 16 million.
Also extend BTF kind encoding from 5 to 7 bits, giving a maximum
available number of kinds of 128. Since with the BTF location work
we use another 3 kinds, we are fast approaching the current limit
of 32.
Convert BTF_MAX_* values to enums to allow them to be encoded in
kernel BTF; this will allow us to detect if the running kernel
supports a 24-bit vlen or not. Add one for max _possible_
(not used) kind.
Fix up a few places in the kernel where a 16-bit vlen is assumed;
remove BTF_INFO_MASK as now all bits are used.
The vlen expansion was suggested by Andrii in [1]; the kind expansion
is tackled here too as it may be needed also to support new kinds
in BTF.
[1] https://lore.kernel.org/bpf/CAEf4BzZx=X6vGqcA8SPU6D+v6k+TR=ZewebXMuXtpmML058piw@mail.gmail.com/
Suggested-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alan Maguire <alan.maguire@oracle.com>
Acked-by: Mykyta Yatsenko <yatsenko@meta.com>
Link: https://lore.kernel.org/r/20260417143023.1551481-2-alan.maguire@oracle.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This odd file was added to automatically figure out tool-generated
symbols.
Honestly, it *should* have been just a real honest-to-goodness regular
file in git, instead of having strange code to generate it in the
Makefile, but that is not how that silly thing works. So now we need to
ignore it explicitly.
Fixes: 1211907ac0 ("tracing: Generate undef symbols allowlist for simple_ring_buffer")
Cc: Vincent Donnefort <vdonnefort@google.com>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Steven Rostedt (Google) <rostedt@goodmis.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Marc Zyngier <maz@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Merge tag 'printk-for-7.1' of git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux
Pull printk updates from Petr Mladek:
- Fix printk ring buffer initialization and sanity checks
- Workaround printf kunit test compilation with gcc < 12.1
- Add IPv6 address printf format tests
- Misc code and documentation cleanup
* tag 'printk-for-7.1' of git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux:
printf: Compile the kunit test with DISABLE_BRANCH_PROFILING DISABLE_BRANCH_PROFILING
lib/vsprintf: use bool for local decode variable
lib/hexdump: print_hex_dump_bytes() calls print_hex_dump_debug()
printk: ringbuffer: fix errors in comments
printk_ringbuffer: Add sanity check for 0-size data
printk_ringbuffer: Fix get_data() size sanity check
printf: add IPv6 address format tests
printk: Fix _DESCS_COUNT type for 64-bit systems
remove_waiter() is used by the slowlock paths, but it is also used for
proxy-lock rollback in rt_mutex_start_proxy_lock() when invoked from
futex_requeue().
In the latter case waiter::task is not current, but remove_waiter()
operates on current for the dequeue operation. That results in several
problems:
1) the rbtree dequeue happens without waiter::task::pi_lock being held
2) the waiter task's pi_blocked_on state is not cleared, which leaves a
dangling pointer primed for UAF around.
3) rt_mutex_adjust_prio_chain() operates on the wrong top priority waiter
task
Use waiter::task instead of current in all related operations in
remove_waiter() to cure those problems.
[ tglx: Fixup rt_mutex_adjust_prio_chain(), add a comment and amend the
changelog ]
Fixes: 8161239a8b ("rtmutex: Simplify PI algorithm and make highest prio task get lock")
Reported-by: Yuan Tan <yuantan098@gmail.com>
Reported-by: Yifan Wu <yifanwucs@gmail.com>
Reported-by: Juefei Pu <tomapufckgml@gmail.com>
Reported-by: Xin Liu <bird@lzu.edu.cn>
Signed-off-by: Keenan Dong <keenanat2000@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Cc: stable@vger.kernel.org
Pull to receive:
2d2b026c3e ("sched_ext: Deny SCX kfuncs to non-SCX struct_ops programs")
which modifies scx_kfunc_context_filter() to avoid conflicts with planned
changes in for-7.2.
Signed-off-by: Tejun Heo <tj@kernel.org>
scx_kfunc_context_filter() currently allows non-SCX struct_ops programs
(e.g. tcp_congestion_ops) to call SCX unlocked kfuncs. This is wrong
for two reasons:
- It is semantically incorrect: a TCP congestion control program has no
business calling SCX kfuncs such as scx_bpf_kick_cpu().
- With CONFIG_EXT_SUB_SCHED=y, kfuncs like scx_bpf_kick_cpu() call
scx_prog_sched(aux), which invokes bpf_prog_get_assoc_struct_ops(aux)
and casts the result to struct sched_ext_ops * before reading ops->priv.
For a non-SCX struct_ops program the returned pointer is the kdata of
that struct_ops type, which is far smaller than sched_ext_ops, making
the read an out-of-bounds access (confirmed with KASAN).
Extend the filter to cover scx_kfunc_set_any and scx_kfunc_set_idle as
well, and deny all SCX kfuncs for any struct_ops program that is not the
SCX struct_ops. This addresses both issues: the semantic contract is
enforced at the verifier level, and the runtime out-of-bounds access
becomes unreachable.
Fixes: d1d3c1c6ae ("sched_ext: Add verifier-time kfunc context filter")
Suggested-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Cheng-Yang Chou <yphbchou0911@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
BPF schedulers that can't hold task_struct pointers (arena-backed ones in
particular) key tasks by pid. During exit, pid is released before the
task finishes passing through scheduler callbacks, so a dying task
becomes invisible to the BPF side mid-schedule. scx_qmap hits this: an
exiting task's dispatch callback can't recover its queue entry, stalling
dispatch until SCX_EXIT_ERROR_STALL.
Add a unique non-zero u64 p->scx.tid assigned at fork that survives the
full task lifetime including exit. scx_bpf_tid_to_task() looks up the
task; unlike bpf_task_from_pid(), it handles exiting tasks.
The lookup costs an rhashtable insert/remove under scx_tasks_lock, so
root schedulers opt in via SCX_OPS_TID_TO_TASK. Sub-schedulers that set
the flag to declare a dependency are rejected at attach if root didn't
opt in.
scx_qmap converted: keys tasks by tid and enables SCX_OPS_ENQ_EXITING.
Pre-patch it stalls within seconds under a non-leader-exec workload;
with the patch it runs cleanly.
v3: Warn on rhashtable_lookup_insert_fast() failure via new
scx_tid_hash_insert() helper (Cheng-Yang Chou).
v2: Guard scx_root deref in scx_bpf_tid_to_task() error path. The kfunc
is registered via scx_kfunc_set_any and reachable from tracing and
syscall programs when no scheduler is attached (Cheng-Yang Chou).
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Cheng-Yang Chou <yphbchou0911@gmail.com>
Reviewed-by: Andrea Righi <arighi@nvidia.com>
Pull to receive 73bd122778 ("rhashtable: Restore insecure_elasticity
toggle") as a dependency for upcoming patches that use
.insecure_elasticity = true on their rhashtables.
Signed-off-by: Tejun Heo <tj@kernel.org>
scx_sched_hash is inserted into under scx_sched_lock (raw_spinlock_irq)
in scx_link_sched(). rhashtable's sync grow path calls get_random_u32()
and does a GFP_ATOMIC allocation; both acquire regular spinlocks, which
is unsafe under raw_spinlock_t. Set insecure_elasticity to skip the
sync grow.
v2:
- Dropped dsq_hash changes. Insertion is not under raw_spin_lock.
- Switched from no_sync_grow flag to insecure_elasticity.
Fixes: 25037af712 ("sched_ext: Add rhashtable lookup for sub-schedulers")
Signed-off-by: Tejun Heo <tj@kernel.org>
Everything:
Total patches: 121
Reviews/patch: 2.11
Reviewed rate: 90%
Excluding DAMON:
Total patches: 113
Reviews/patch: 2.25
Reviewed rate: 96%
- The 33 patch series "Eliminate Dying Memory Cgroup" from Qi Zheng and
Muchun Song addresses the longstanding "dying memcg problem". A
situation wherein a no-longer-used memory control group will hang around
for an extended period pointlessly consuming memory. The [0/N]
changelog has a good overview of this work.
- The 3 patch series "fix unexpected type conversions and potential
overflows" from Qi Zheng fixes a couple of potential 32-bit/64-bit
issues which were identified during review of the "Eliminate Dying
Memory Cgroup" series.
- The 6 patch series "kho: history: track previous kernel version and
kexec boot count" from Breno Leitao uses Kexec Handover (KHO) to pass
the previous kernel's version string and the number of kexec reboots
since the last cold boot to the next kernel, and prints it at boot time.
- The 4 patch series "liveupdate: prevent double preservation" from
Pasha Tatashin teaches LUO to avoid managing the same file across
different active sessions.
- The 10 patch series "liveupdate: Fix module unloading and unregister
API" from Pasha Tatashin addresses an issue with how LUO handles module
reference counting and unregistration during module unloading.
- The 2 patch series "zswap pool per-CPU acomp_ctx simplifications" from
Kanchana Sridhar simplifies and cleans up the zswap crypto compression
handling and improves the lifecycle management of zswap pool's per-CPU
acomp_ctx resources.
- The 2 patch series "mm/damon/core: fix damon_call()/damos_walk() vs
kdmond exit race" from SeongJae Park addresses unlikely but possible
leaks and deadlocks in damon_call() and damon_walk().
- The 2 patch series "mm/damon/core: validate damos_quota_goal->nid"
from SeongJae Park fixes a couple of root-only wild pointer
dereferences.
- The 2 patch series "Docs/admin-guide/mm/damon: warn commit_inputs vs
other params race" from SeongJae Park updates the DAMON documentation to
warn operators about potential races which can occur if the
commit_inputs parameter is altered at the wrong time.
- The 3 patch series "Minor hmm_test fixes and cleanups" from Alistair
Popple implements two bugfixes a cleanup for the HMM kernel selftests.
- The 6 patch series "Modify memfd_luo code" from Chenghao Duan provides
cleanups, simplifications and speedups in the memfd_lou code.
- The 4 patch series "mm, kvm: allow uffd support in guest_memfd" from
Mike Rapoport enables support for userfaultfd in guest_memfd.
- The 6 patch series "selftests/mm: skip several tests when thp is not
available" from Chunyu Hu fixes several issues in the selftests code
which were causing breakage when the tests were run on CONFIG_THP=n
kernels.
- The 2 patch series "mm/mprotect: micro-optimization work" from Pedro
Falcato implements a couple of nice speedups for mprotect().
- The 3 patch series "MAINTAINERS: update KHO and LIVE UPDATE entries"
from Pratyush Yadav reflects upcoming changes in the maintenance of KHO,
LUO, memfd_luo, kexec, crash, kdump and probably other kexec-based
things - they are being moved out of mm.git and into a new git tree.
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Merge tag 'mm-stable-2026-04-18-02-14' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Pull more MM updates from Andrew Morton:
- "Eliminate Dying Memory Cgroup" (Qi Zheng and Muchun Song)
Address the longstanding "dying memcg problem". A situation wherein a
no-longer-used memory control group will hang around for an extended
period pointlessly consuming memory
- "fix unexpected type conversions and potential overflows" (Qi Zheng)
Fix a couple of potential 32-bit/64-bit issues which were identified
during review of the "Eliminate Dying Memory Cgroup" series
- "kho: history: track previous kernel version and kexec boot count"
(Breno Leitao)
Use Kexec Handover (KHO) to pass the previous kernel's version string
and the number of kexec reboots since the last cold boot to the next
kernel, and print it at boot time
- "liveupdate: prevent double preservation" (Pasha Tatashin)
Teach LUO to avoid managing the same file across different active
sessions
- "liveupdate: Fix module unloading and unregister API" (Pasha
Tatashin)
Address an issue with how LUO handles module reference counting and
unregistration during module unloading
- "zswap pool per-CPU acomp_ctx simplifications" (Kanchana Sridhar)
Simplify and clean up the zswap crypto compression handling and
improve the lifecycle management of zswap pool's per-CPU acomp_ctx
resources
- "mm/damon/core: fix damon_call()/damos_walk() vs kdmond exit race"
(SeongJae Park)
Address unlikely but possible leaks and deadlocks in damon_call() and
damon_walk()
- "mm/damon/core: validate damos_quota_goal->nid" (SeongJae Park)
Fix a couple of root-only wild pointer dereferences
- "Docs/admin-guide/mm/damon: warn commit_inputs vs other params race"
(SeongJae Park)
Update the DAMON documentation to warn operators about potential
races which can occur if the commit_inputs parameter is altered at
the wrong time
- "Minor hmm_test fixes and cleanups" (Alistair Popple)
Bugfixes and a cleanup for the HMM kernel selftests
- "Modify memfd_luo code" (Chenghao Duan)
Cleanups, simplifications and speedups to the memfd_lou code
- "mm, kvm: allow uffd support in guest_memfd" (Mike Rapoport)
Support for userfaultfd in guest_memfd
- "selftests/mm: skip several tests when thp is not available" (Chunyu
Hu)
Fix several issues in the selftests code which were causing breakage
when the tests were run on CONFIG_THP=n kernels
- "mm/mprotect: micro-optimization work" (Pedro Falcato)
A couple of nice speedups for mprotect()
- "MAINTAINERS: update KHO and LIVE UPDATE entries" (Pratyush Yadav)
Document upcoming changes in the maintenance of KHO, LUO, memfd_luo,
kexec, crash, kdump and probably other kexec-based things - they are
being moved out of mm.git and into a new git tree
* tag 'mm-stable-2026-04-18-02-14' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (121 commits)
MAINTAINERS: add page cache reviewer
mm/vmscan: avoid false-positive -Wuninitialized warning
MAINTAINERS: update Dave's kdump reviewer email address
MAINTAINERS: drop include/linux/liveupdate from LIVE UPDATE
MAINTAINERS: drop include/linux/kho/abi/ from KHO
MAINTAINERS: update KHO and LIVE UPDATE maintainers
MAINTAINERS: update kexec/kdump maintainers entries
mm/migrate_device: remove dead migration entry check in migrate_vma_collect_huge_pmd()
selftests: mm: skip charge_reserved_hugetlb without killall
userfaultfd: allow registration of ranges below mmap_min_addr
mm/vmstat: fix vmstat_shepherd double-scheduling vmstat_update
mm/hugetlb: fix early boot crash on parameters without '=' separator
zram: reject unrecognized type= values in recompress_store()
docs: proc: document ProtectionKey in smaps
mm/mprotect: special-case small folios when applying permissions
mm/mprotect: move softleaf code out of the main function
mm: remove '!root_reclaim' checking in should_abort_scan()
mm/sparse: fix comment for section map alignment
mm/page_io: use sio->len for PSWPIN accounting in sio_read_complete()
selftests/mm: transhuge_stress: skip the test when thp not available
...
Redefine dynptr mutability and fix inconsistency in the verifier and
kfunc signatures. Dynptr mutability is at two levels. The first is
the bpf_dynptr structure and the second is the memory the dynptr points
to. The verifer currently tracks the mutability of the bpf_dynptr struct
through helper and kfunc prototypes, where "const struct bpf_dynptr *"
means the structure itself is immutable. The second level is tracked
in upper bit of bpf_dynptr->size in runtime and is not changed in this
patch.
There are two type of inconsistency in the verfier regarding the
mutability of the bpf_dynptr struct. First, there are many existing
kfuncs whose prototypes are wrong. For example, bpf_dynptr_adjust()
mutates a dynptr's start and offset but marks the argument as a const
pointer. At the same time many other kfuncs that does not mutate the
dynptr but mark themselves as mutable. Second, the verifier currently
does not honor the const qualifier in kfunc prototypes as it determines
whether tagging the arg_type with MEM_RDONLY or not based on the register
state.
Since all the verifier care is to prevent CONST_PTR_TO_DYNPTR from
being destroyed in callback and global subprogram, redefine the
mutability at the bpf_dynptr level to just bpf_dynptr_kern->data. Then,
explicitly prohibit passing CONST_PTR_TO_DYNPTR to an argument tagged
with MEM_UNINIT or OBJ_RELEASE. The mutability of a dynptr's view is not
really interesting so drop MEM_RDONLY annotation for dynptr from the
helpers and kfuncs. Plus, if the mutability of the entire bpf_dynptr
were to be done correctly, it would kill the bpf_dynptr_adjust() usage
in callback and global subporgram.
Implementation wise
- First, make sure all kfunc arg are correctly tagged: Tag the dynptr
argument of bpf_dynptr_file_discard() with OBJ_RELEASE.
- Then, in process_dynptr_func(), make sure CONST_PTR_TO_DYNPTR cannot
be passed to argument tagged with MEM_UNINIT or OBJ_RELEASE. For
MEM_UNINIT, it is already checked by is_dynptr_reg_valid_uninit().
For OBJ_RELEASE, check against OBJ_RELEASE instead of MEM_RDONLY and
drop a now identical check in unmark_stack_slots_dynptr().
- Remove the mutual exclusive check between MEM_UNINIT and MEM_RDONLY,
but don't add a MEM_UNINIT and OBJ_RELEASE version as it is obviously
wrong.
Note that while this patch stops following the C semantic for the
mutability of bpf_dynptr, the prototype of kfuncs are still fixed to
maintain the correct C semantics in the implementation. Adding or
removing the const qualifier does not break backward compatibility.
In addition, fix kfuncs dropping the const qualifier when casting the
opaque bpf_dynptr to bpf_dynptr_kern.
In test_kfunc_dynptr_param.c, initialize dynptr to 0 to avoid
-Wuninitialized-const-pointer warning.
Signed-off-by: Amery Hung <ameryhung@gmail.com>
Acked-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/bpf/20260414191014.1218567-1-ameryhung@gmail.com
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
* improve debugability of reserve_mem kernel parameter handling with print
outs in case of a failure and debugfs info showing what was actually
reserved
* Make memblock_free_late() and free_reserved_area() use the same core
logic for freeing the memory to buddy and ensure it takes care of
updating memblock arrays when ARCH_KEEP_MEMBLOCK is enabled.
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Merge tag 'memblock-v7.1-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rppt/memblock
Pull memblock updates from Mike Rapoport:
- improve debuggability of reserve_mem kernel parameter handling with
print outs in case of a failure and debugfs info showing what was
actually reserved
- Make memblock_free_late() and free_reserved_area() use the same core
logic for freeing the memory to buddy and ensure it takes care of
updating memblock arrays when ARCH_KEEP_MEMBLOCK is enabled.
* tag 'memblock-v7.1-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rppt/memblock:
x86/alternative: delay freeing of smp_locks section
memblock: warn when freeing reserved memory before memory map is initialized
memblock, treewide: make memblock_free() handle late freeing
memblock: make free_reserved_area() update memblock if ARCH_KEEP_MEMBLOCK=y
memblock: extract page freeing from free_reserved_area() into a helper
memblock: make free_reserved_area() more robust
mm: move free_reserved_area() to mm/memblock.c
powerpc: opal-core: pair alloc_pages_exact() with free_pages_exact()
powerpc: fadump: pair alloc_pages_exact() with free_pages_exact()
memblock: reserve_mem: fix end caclulation in reserve_mem_release_by_name()
memblock: move reserve_bootmem_range() to memblock.c and make it static
memblock: Add reserve_mem debugfs info
memblock: Print out errors on reserve_mem parser
Stop pinning modules indefinitely upon file handler registration.
Instead, dynamically increment the module reference count only when a live
update session actively uses the file handler (e.g., during preservation
or deserialization), and release it when the session ends.
This allows modules providing live update handlers to be gracefully
unloaded when no live update is in progress.
Link: https://lore.kernel.org/20260327033335.696621-11-pasha.tatashin@soleen.com
Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Reviewed-by: Pratyush Yadav (Google) <pratyush@kernel.org>
Cc: David Matlack <dmatlack@google.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Samiullah Khawaja <skhawaja@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Change liveupdate_unregister_file_handler and liveupdate_unregister_flb to
return void instead of an error code. This follows the design principle
that unregistration during module unload should not fail, as the unload
cannot be stopped at that point.
Link: https://lore.kernel.org/20260327033335.696621-10-pasha.tatashin@soleen.com
Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Reviewed-by: Pratyush Yadav (Google) <pratyush@kernel.org>
Cc: David Matlack <dmatlack@google.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Samiullah Khawaja <skhawaja@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Now that file handler unregistration automatically unregisters all
associated file handlers (FLBs), the liveupdate_test_unregister() function
is no longer needed. Remove it along with its usages and declarations.
Link: https://lore.kernel.org/20260327033335.696621-9-pasha.tatashin@soleen.com
Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Reviewed-by: Pratyush Yadav (Google) <pratyush@kernel.org>
Cc: David Matlack <dmatlack@google.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Samiullah Khawaja <skhawaja@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
To ensure that unregistration is always successful and doesn't leave
dangling resources, introduce auto-unregistration of FLBs: when a file
handler is unregistered, all FLBs associated with it are automatically
unregistered.
Introduce a new helper luo_flb_unregister_all() which unregisters all FLBs
linked to the given file handler.
Link: https://lore.kernel.org/20260327033335.696621-8-pasha.tatashin@soleen.com
Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Reviewed-by: Pratyush Yadav (Google) <pratyush@kernel.org>
Cc: David Matlack <dmatlack@google.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Samiullah Khawaja <skhawaja@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Now that FLB module references are handled dynamically during active
sessions, we can safely remove the luo_session_quiesce() and
luo_session_resume() mechanism.
Link: https://lore.kernel.org/20260327033335.696621-7-pasha.tatashin@soleen.com
Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Reviewed-by: Pratyush Yadav (Google) <pratyush@kernel.org>
Cc: David Matlack <dmatlack@google.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Samiullah Khawaja <skhawaja@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Stop pinning modules indefinitely upon FLB registration. Instead,
dynamically take a module reference when the FLB is actively used in a
session (e.g., during preserve and retrieve) and release it when the
session concludes.
This allows modules providing FLB operations to be cleanly unloaded when
not in active use by the live update orchestrator.
Link: https://lore.kernel.org/20260327033335.696621-6-pasha.tatashin@soleen.com
Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Reviewed-by: Samiullah Khawaja <skhawaja@google.com>
Reviewed-by: Pratyush Yadav (Google) <pratyush@kernel.org>
Cc: David Matlack <dmatlack@google.com>
Cc: Mike Rapoport <rppt@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Because liveupdate FLB objects will soon drop their persistent module
references when registered, list traversals must be protected against
concurrent module unloading.
To provide this protection, utilize the global luo_register_rwlock. It
protects the global registry of FLBs and the handler's specific list of
FLB dependencies.
Read locks are used during concurrent list traversals (e.g., during
preservation and serialization). Write locks are taken during
registration and unregistration.
Link: https://lore.kernel.org/20260327033335.696621-5-pasha.tatashin@soleen.com
Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Reviewed-by: Pratyush Yadav (Google) <pratyush@kernel.org>
Cc: David Matlack <dmatlack@google.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Samiullah Khawaja <skhawaja@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Because liveupdate file handlers will no longer hold a module reference
when registered, we must ensure that the access to the handler list is
protected against concurrent module unloading.
Utilize the global luo_register_rwlock to protect the global registry of
file handlers. Read locks are taken during list traversals in
luo_preserve_file() and luo_file_deserialize(). Write locks are taken
during registration and unregistration.
Link: https://lore.kernel.org/20260327033335.696621-4-pasha.tatashin@soleen.com
Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Reviewed-by: Pratyush Yadav (Google) <pratyush@kernel.org>
Cc: David Matlack <dmatlack@google.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Samiullah Khawaja <skhawaja@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
The luo_flb_get_private() function, which is responsible for lazily
initializing the private state of FLB objects, can be called concurrently
from multiple threads. This creates a data race on the 'initialized' flag
and can lead to multiple executions of mutex_init() and INIT_LIST_HEAD()
on the same memory.
Introduce a static spinlock (luo_flb_init_lock) local to the function to
synchronize the initialization path. Use smp_load_acquire() and
smp_store_release() for memory ordering between the fast path and the slow
path.
Link: https://lore.kernel.org/20260327033335.696621-3-pasha.tatashin@soleen.com
Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Reviewed-by: Pratyush Yadav <pratyush@kernel.org>
Cc: David Matlack <dmatlack@google.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Samiullah Khawaja <skhawaja@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Patch series "liveupdate: Fix module unloading and unregister API", v3.
This patch series addresses an issue with how LUO handles module reference
counting and unregistration during a module unload (e.g., via rmmod).
Currently, modules that register live update file handlers are pinned for
the entire duration they are registered. This prevents the modules from
being unloaded gracefully, even when no live update session is in
progress.
Furthermore, if a module is forcefully unloaded, the unregistration
functions return an error (e.g. -EBUSY) if a session is active, which is
ignored by the kernel's module unload path, leaving dangling pointers in
the LUO global lists.
To resolve these issues, this series introduces the following changes:
1. Adds a global read-write semaphore (luo_register_rwlock) to protect
the registration lists for both file handlers and FLBs.
2. Reduces the scope of module reference counting for file handlers and
FLBs. Instead of pinning modules indefinitely upon registration,
references are now taken only when they are actively used in a live
update session (e.g., during preservation, retrieval, or
deserialization).
3. Removes the global luo_session_quiesce() mechanism since module
unload behavior now handles active sessions implicitly.
4. Introduces auto-unregistration of FLBs during file handler
unregistration to prevent leaving dangling resources.
5. Changes the unregistration functions to return void instead of
an error code.
6. Fixes a data race in luo_flb_get_private() by introducing a spinlock
for thread-safe lazy initialization.
7. Strengthens security by using %.*s when printing untrusted deserialized
compatible strings and session names to prevent out-of-bounds reads.
This patch (of 10):
Deserialized strings from KHO data (such as file handler compatible
strings and session names) are provided by the previous kernel and might
not be null-terminated if the data is corrupted or maliciously crafted.
When printing these strings in error messages, use the %.*s format
specifier with the maximum buffer size to prevent out-of-bounds reads into
adjacent kernel memory.
Link: https://lore.kernel.org/20260327033335.696621-1-pasha.tatashin@soleen.com
Link: https://lore.kernel.org/20260327033335.696621-2-pasha.tatashin@soleen.com
Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Reviewed-by: Pratyush Yadav (Google) <pratyush@kernel.org>
Cc: David Matlack <dmatlack@google.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Samiullah Khawaja <skhawaja@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Patch series "liveupdate: prevent double preservation", v4.
Currently, LUO does not prevent the same file from being managed twice
across different active sessions.
Because LUO preserves files of absolutely different types: memfd, and
upcoming vfiofd [1], iommufd [2], guestmefd (and possible kvmfd/cpufd).
There is no common private data or guarantee on how to prevent that the
same file is not preserved twice beside using inode or some slower and
expensive method like hashtables.
This patch (of 4)
Currently, LUO does not prevent the same file from being managed twice
across different active sessions.
Use a global xarray luo_preserved_files to keep track of file identifiers
being preserved by LUO. Update luo_preserve_file() to check and insert
the file identifier into this xarray when it is preserved, and erase it in
luo_file_unpreserve_files() when it is released.
To allow handlers to define what constitutes a "unique" file (e.g.,
different struct file objects pointing to the same hardware resource), add
a get_id() callback to struct liveupdate_file_ops. If not provided, the
default identifier is the struct file pointer itself.
This ensures that the same file (or resource) cannot be managed by
multiple sessions. If another session attempts to preserve an already
managed file, it will now fail with -EBUSY.
Link: https://lore.kernel.org/20260326163943.574070-1-pasha.tatashin@soleen.com
Link: https://lore.kernel.org/20260326163943.574070-2-pasha.tatashin@soleen.com
Link: https://lore.kernel.org/all/20260129212510.967611-1-dmatlack@google.com [1]
Link: https://lore.kernel.org/all/20260203220948.2176157-1-skhawaja@google.com [2]
Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Reviewed-by: Samiullah Khawaja <skhawaja@google.com>
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Cc: David Matlack <dmatlack@google.com>
Cc: Pratyush Yadav <pratyush@kernel.org>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Christian Brauner <brauner@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Use Kexec Handover (KHO) to pass the previous kernel's version string and
the number of kexec reboots since the last cold boot to the next kernel,
and print it at boot time.
Example output:
[ 0.000000] KHO: exec from: 6.19.0-rc4-next-20260107 (count 1)
Motivation
==========
Bugs that only reproduce when kexecing from specific kernel versions are
difficult to diagnose. These issues occur when a buggy kernel kexecs into
a new kernel, with the bug manifesting only in the second kernel.
Recent examples include the following commits:
* commit eb22663125 ("x86/boot: Fix page table access in
5-level to 4-level paging transition")
* commit 77d48d39e9 ("efistub/tpm: Use ACPI reclaim memory
for event log to avoid corruption")
* commit 64b45dd46e ("x86/efi: skip memattr table on kexec
boot")
As kexec-based reboots become more common, these version-dependent bugs
are appearing more frequently. At scale, correlating crashes to the
previous kernel version is challenging, especially when issues only occur
in specific transition scenarios.
Implementation
==============
The kexec metadata is stored as a plain C struct (struct
kho_kexec_metadata) rather than FDT format, for simplicity and direct
field access. It is registered via kho_add_subtree() as a separate
subtree, keeping it independent from the core KHO ABI. This design
choice:
- Keeps the core KHO ABI minimal and stable
- Allows the metadata format to evolve independently
- Avoids requiring version bumps for all KHO consumers (LUO, etc.)
when the metadata format changes
The struct kho_kexec_metadata contains two fields:
- previous_release: The kernel version that initiated the kexec
- kexec_count: Number of kexec boots since last cold boot
On cold boot, kexec_count starts at 0 and increments with each kexec. The
count helps identify issues that only manifest after multiple consecutive
kexec reboots.
[leitao@debian.org: call kho_kexec_metadata_init() for both boot paths]
Link: https://lore.kernel.org/all/20260309-kho-v8-5-c3abcf4ac750@debian.org/ [1]
Link: https://lore.kernel.org/20260409-kho_fix_merge_issue-v1-1-710c84ceaa85@debian.org
Link: https://lore.kernel.org/20260316-kho-v9-5-ed6dcd951988@debian.org
Signed-off-by: Breno Leitao <leitao@debian.org>
Acked-by: SeongJae Park <sj@kernel.org>
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Reviewed-by: Pratyush Yadav <pratyush@kernel.org>
Cc: Alexander Graf <graf@amazon.com>
Cc: David Hildenbrand <david@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: "Liam R. Howlett" <Liam.Howlett@oracle.com>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: Shuah Khan <skhan@linuxfoundation.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
kho_in_debugfs_init() calls fdt_totalsize() to determine blob sizes, which
assumes all blobs are FDTs. This breaks for non-FDT blobs like struct
kho_kexec_metadata.
Fix this by reading the "blob-size" property from the FDT (persisted by
kho_add_subtree()) instead of calling fdt_totalsize(). Also rename local
variables from fdt_phys/sub_fdt to blob_phys/blob for consistency with the
non-FDT-specific naming.
Link: https://lore.kernel.org/20260316-kho-v9-4-ed6dcd951988@debian.org
Signed-off-by: Breno Leitao <leitao@debian.org>
Reviewed-by: Pratyush Yadav <pratyush@kernel.org>
Cc: Alexander Graf <graf@amazon.com>
Cc: David Hildenbrand <david@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: "Liam R. Howlett" <Liam.Howlett@oracle.com>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport (Microsoft) <rppt@kernel.org>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: SeongJae Park <sj@kernel.org>
Cc: Shuah Khan <skhan@linuxfoundation.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
kho_add_subtree() accepts a size parameter but only forwards it to
debugfs. The size is not persisted in the KHO FDT, so it is lost across
kexec. This makes it impossible for the incoming kernel to determine the
blob size without understanding the blob format.
Store the blob size as a "blob-size" property in the KHO FDT alongside the
"preserved-data" physical address. This allows the receiving kernel to
recover the size for any blob regardless of format.
Also extend kho_retrieve_subtree() with an optional size output parameter
so callers can learn the blob size without needing to understand the blob
format. Update all callers to pass NULL for the new parameter.
Link: https://lore.kernel.org/20260316-kho-v9-3-ed6dcd951988@debian.org
Signed-off-by: Breno Leitao <leitao@debian.org>
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Reviewed-by: Pratyush Yadav <pratyush@kernel.org>
Cc: Alexander Graf <graf@amazon.com>
Cc: David Hildenbrand <david@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: "Liam R. Howlett" <Liam.Howlett@oracle.com>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: SeongJae Park <sj@kernel.org>
Cc: Shuah Khan <skhan@linuxfoundation.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Since kho_add_subtree() now accepts arbitrary data blobs (not just FDTs),
rename the parameter from 'fdt' to 'blob' to better reflect its purpose.
Apply the same rename to kho_remove_subtree() for consistency.
Also rename kho_debugfs_fdt_add() and kho_debugfs_fdt_remove() to
kho_debugfs_blob_add() and kho_debugfs_blob_remove() respectively, with
the same parameter rename from 'fdt' to 'blob'.
Link: https://lore.kernel.org/20260316-kho-v9-2-ed6dcd951988@debian.org
Signed-off-by: Breno Leitao <leitao@debian.org>
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Reviewed-by: Pratyush Yadav <pratyush@kernel.org>
Cc: Alexander Graf <graf@amazon.com>
Cc: David Hildenbrand <david@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: "Liam R. Howlett" <Liam.Howlett@oracle.com>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: SeongJae Park <sj@kernel.org>
Cc: Shuah Khan <skhan@linuxfoundation.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Patch series "kho: history: track previous kernel version and kexec boot
count", v9.
Use Kexec Handover (KHO) to pass the previous kernel's version string and
the number of kexec reboots since the last cold boot to the next kernel,
and print it at boot time.
Example
=======
[ 0.000000] Linux version 6.19.0-rc3-upstream-00047-ge5d992347849
...
[ 0.000000] KHO: exec from: 6.19.0-rc4-next-20260107upstream-00004-g3071b0dc4498 (count 1)
Motivation
==========
Bugs that only reproduce when kexecing from specific kernel versions are
difficult to diagnose. These issues occur when a buggy kernel kexecs into
a new kernel, with the bug manifesting only in the second kernel.
Recent examples include:
* eb22663125 ("x86/boot: Fix page table access in 5-level to 4-level paging transition")
* 77d48d39e9 ("efistub/tpm: Use ACPI reclaim memory for event log to avoid corruption")
* 64b45dd46e ("x86/efi: skip memattr table on kexec boot")
As kexec-based reboots become more common, these version-dependent bugs
are appearing more frequently. At scale, correlating crashes to the
previous kernel version is challenging, especially when issues only occur
in specific transition scenarios.
Some bugs manifest only after multiple consecutive kexec reboots.
Tracking the kexec count helps identify these cases (this metric is
already used by live update sub-system).
KHO provides a reliable mechanism to pass information between kernels. By
carrying the previous kernel's release string and kexec count forward, we
can print this context at boot time to aid debugging.
The goal of this feature is to have this information being printed in
early boot, so, users can trace back kernel releases in kexec. Systemd is
not helpful because we cannot assume that the previous kernel has systemd
or even write access to the disk (common when using Linux as bootloaders)
This patch (of 6):
kho_add_subtree() assumes the fdt argument is always an FDT and calls
fdt_totalsize() on it in the debugfs code path. This assumption will
break if a caller passes arbitrary data instead of an FDT.
When CONFIG_KEXEC_HANDOVER_DEBUGFS is enabled, kho_debugfs_fdt_add() calls
__kho_debugfs_fdt_add(), which executes:
f->wrapper.size = fdt_totalsize(fdt);
Fix this by adding an explicit size parameter to kho_add_subtree() so
callers specify the blob size. This allows subtrees to contain arbitrary
data formats, not just FDTs. Update all callers:
- memblock.c: use fdt_totalsize(fdt)
- luo_core.c: use fdt_totalsize(fdt_out)
- test_kho.c: use fdt_totalsize()
- kexec_handover.c (root fdt): use fdt_totalsize(kho_out.fdt)
Also update __kho_debugfs_fdt_add() to receive the size explicitly instead
of computing it internally via fdt_totalsize(). In kho_in_debugfs_init(),
pass fdt_totalsize() for the root FDT and sub-blobs since all current
users are FDTs. A subsequent patch will persist the size in the KHO FDT
so the incoming side can handle non-FDT blobs correctly.
Link: https://lore.kernel.org/20260323110747.193569-1-duanchenghao@kylinos.cn
Link: https://lore.kernel.org/20260316-kho-v9-1-ed6dcd951988@debian.org
Signed-off-by: Breno Leitao <leitao@debian.org>
Suggested-by: Pratyush Yadav <pratyush@kernel.org>
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Reviewed-by: Pratyush Yadav <pratyush@kernel.org>
Cc: Alexander Graf <graf@amazon.com>
Cc: David Hildenbrand <david@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: "Liam R. Howlett" <Liam.Howlett@oracle.com>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: SeongJae Park <sj@kernel.org>
Cc: Shuah Khan <skhan@linuxfoundation.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
To resolve the dying memcg issue, we need to reparent LRU folios of child
memcg to its parent memcg. This could cause problems for non-hierarchical
stats.
As Yosry Ahmed pointed out:
In short, if memory is charged to a dying cgroup at the time of
reparenting, when the memory gets uncharged the stats updates will occur
at the parent. This will update both hierarchical and non-hierarchical
stats of the parent, which would corrupt the parent's non-hierarchical
stats (because those counters were never incremented when the memory was
charged).
Now we have the following two types of non-hierarchical stats, and they
are only used in CONFIG_MEMCG_V1:
a. memcg->vmstats->state_local[i]
b. pn->lruvec_stats->state_local[i]
To ensure that these non-hierarchical stats work properly, we need to
reparent these non-hierarchical stats after reparenting LRU folios. To
this end, this commit makes the following preparations:
1. implement reparent_state_local() to reparent non-hierarchical stats
2. make css_killed_work_fn() to be called in rcu work, and implement
get_non_dying_memcg_start() and get_non_dying_memcg_end() to avoid race
between mod_memcg_state()/mod_memcg_lruvec_state()
and reparent_state_local()
Link: https://lore.kernel.org/e862995c45a7101a541284b6ebee5e5c32c89066.1772711148.git.zhengqi.arch@bytedance.com
Co-developed-by: Yosry Ahmed <yosry@kernel.org>
Signed-off-by: Yosry Ahmed <yosry@kernel.org>
Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com>
Acked-by: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Allen Pais <apais@linux.microsoft.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Chengming Zhou <chengming.zhou@linux.dev>
Cc: Chen Ridong <chenridong@huawei.com>
Cc: David Hildenbrand <david@kernel.org>
Cc: Hamza Mahfooz <hamzamahfooz@linux.microsoft.com>
Cc: Harry Yoo <harry.yoo@oracle.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Imran Khan <imran.f.khan@oracle.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kamalesh Babulal <kamalesh.babulal@oracle.com>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: Liam Howlett <Liam.Howlett@oracle.com>
Cc: Lorenzo Stoakes (Oracle) <ljs@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Michal Koutný <mkoutny@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Usama Arif <usamaarif642@gmail.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: Wei Xu <weixugc@google.com>
Cc: Yuanchu Xie <yuanchu@google.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Merge tag 'bpf-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf
Pull bpf fixes from Alexei Starovoitov:
"Most of the diff stat comes from Xu Kuohai's fix to emit ENDBR/BTI,
since all JITs had to be touched to move constant blinding out and
pass bpf_verifier_env in.
- Fix use-after-free in arena_vm_close on fork (Alexei Starovoitov)
- Dissociate struct_ops program with map if map_update fails (Amery
Hung)
- Fix out-of-range and off-by-one bugs in arm64 JIT (Daniel Borkmann)
- Fix precedence bug in convert_bpf_ld_abs alignment check (Daniel
Borkmann)
- Fix arg tracking for imprecise/multi-offset in BPF_ST/STX insns
(Eduard Zingerman)
- Copy token from main to subprogs to fix missing kallsyms (Eduard
Zingerman)
- Prevent double close and leak of btf objects in libbpf (Jiri Olsa)
- Fix af_unix null-ptr-deref in sockmap (Michal Luczaj)
- Fix NULL deref in map_kptr_match_type for scalar regs (Mykyta
Yatsenko)
- Avoid unnecessary IPIs. Remove redundant bpf_flush_icache() in
arm64 and riscv JITs (Puranjay Mohan)
- Fix out of bounds access. Validate node_id in arena_alloc_pages()
(Puranjay Mohan)
- Reject BPF-to-BPF calls and callbacks in arm32 JIT (Puranjay Mohan)
- Refactor all JITs to pass bpf_verifier_env to emit ENDBR/BTI for
indirect jump targets on x86-64, arm64 JITs (Xu Kuohai)
- Allow UTF-8 literals in bpf_bprintf_prepare() (Yihan Ding)"
* tag 'bpf-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf: (32 commits)
bpf, arm32: Reject BPF-to-BPF calls and callbacks in the JIT
bpf: Dissociate struct_ops program with map if map_update fails
bpf: Validate node_id in arena_alloc_pages()
libbpf: Prevent double close and leak of btf objects
selftests/bpf: cover UTF-8 trace_printk output
bpf: allow UTF-8 literals in bpf_bprintf_prepare()
selftests/bpf: Reject scalar store into kptr slot
bpf: Fix NULL deref in map_kptr_match_type for scalar regs
bpf: Fix precedence bug in convert_bpf_ld_abs alignment check
bpf, arm64: Emit BTI for indirect jump target
bpf, x86: Emit ENDBR for indirect jump targets
bpf: Add helper to detect indirect jump targets
bpf: Pass bpf_verifier_env to JIT
bpf: Move constants blinding out of arch-specific JITs
bpf, sockmap: Take state lock for af_unix iter
bpf, sockmap: Fix af_unix null-ptr-deref in proto update
selftests/bpf: Extend bpf_iter_unix to attempt deadlocking
bpf, sockmap: Fix af_unix iter deadlock
bpf, sockmap: Annotate af_unix sock:: Sk_state data-races
selftests/bpf: verify kallsyms entries for token-loaded subprograms
...
Currently, when bpf_struct_ops_map_update_elem() fails, the programs'
st_ops_assoc will remain set. They may become dangling pointers if the
map is freed later, but they will never be dereferenced since the
struct_ops attachment did not succeed. However, if one of the programs
is subsequently attached as part of another struct_ops map, its
st_ops_assoc will be poisoned even though its old st_ops_assoc was stale
from a failed attachment.
Fix the spurious poisoned st_ops_assoc by dissociating struct_ops
programs with a map if the attachment fails. Move
bpf_prog_assoc_struct_ops() to after *plink++ to make sure
bpf_prog_disassoc_struct_ops() will not miss a program when iterating
st_map->links.
Note that, dissociating a program from a map requires some attention as
it must not reset a poisoned st_ops_assoc or a st_ops_assoc pointing to
another map. The former is already guarded in
bpf_prog_disassoc_struct_ops(). The latter also will not happen since
st_ops_assoc of programs in st_map->links are set by
bpf_prog_assoc_struct_ops(), which can only be poisoned or pointing to
the current map.
Signed-off-by: Amery Hung <ameryhung@gmail.com>
Link: https://lore.kernel.org/r/20260417174900.2895486-1-ameryhung@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
cpuset_can_attach() allocates DL bandwidth only when migrating
deadline tasks to a disjoint CPU mask, but cpuset_cancel_attach()
rolls back based only on nr_migrate_dl_tasks. This makes the DL
bandwidth alloc/free paths asymmetric: rollback can call dl_bw_free()
even when no dl_bw_alloc() was done.
Rollback also needs to undo the reservation against the same CPU/root
domain that was charged. Record the CPU used by dl_bw_alloc() and use
that state in cpuset_cancel_attach(). If no allocation happened,
dl_bw_cpu stays at -1 and rollback skips dl_bw_free(). If allocation
did happen, bandwidth is returned to the same CPU/root domain.
Successful attach paths are unchanged. This only fixes failed attach
rollback accounting.
Fixes: 2ef269ef1a ("cgroup/cpuset: Free DL BW in case can_attach() fails")
Signed-off-by: Guopeng Zhang <zhangguopeng@kylinos.cn>
Reviewed-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Take scx_qmap for example, when sub scheduler is attached, there is
'BPF sub-scheduler "qmap" enabled' message, but when detached, the log
is missing. Add a new function to do the log thing, it can be used by
both root scheduler and sub scheduler.
Signed-off-by: Zhao Mengmeng <zhaomengmeng@kylinos.cn>
Reviewed-by: Cheng-Yang Chou <yphbchou0911@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
- added support for batched cache sync, what improves performance of
dma_map/unmap_sg() operations on ARM64 architecture (Barry Song)
- introduced DMA_ATTR_CC_SHARED attribute for explicitly shared memory
used in confidential computing (Jiri Pirko)
- refactored spaghetti-like code in drivers/of/of_reserved_mem.c and its
clients (Marek Szyprowski, shared branch with device-tree updates to
avoid merge conflicts)
- prepared Contiguous Memory Allocator related code for making dma-buf
drivers modularized (Maxime Ripard)
- added support for benchmarking dma_map_sg() calls to tools/dma utility
(Qinxin Xia)
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Merge tag 'dma-mapping-7.1-2026-04-16' of git://git.kernel.org/pub/scm/linux/kernel/git/mszyprowski/linux
Pull dma-mapping updates from Marek Szyprowski:
- added support for batched cache sync, what improves performance of
dma_map/unmap_sg() operations on ARM64 architecture (Barry Song)
- introduced DMA_ATTR_CC_SHARED attribute for explicitly shared memory
used in confidential computing (Jiri Pirko)
- refactored spaghetti-like code in drivers/of/of_reserved_mem.c and
its clients (Marek Szyprowski, shared branch with device-tree updates
to avoid merge conflicts)
- prepared Contiguous Memory Allocator related code for making dma-buf
drivers modularized (Maxime Ripard)
- added support for benchmarking dma_map_sg() calls to tools/dma
utility (Qinxin Xia)
* tag 'dma-mapping-7.1-2026-04-16' of git://git.kernel.org/pub/scm/linux/kernel/git/mszyprowski/linux: (24 commits)
dma-buf: heaps: system: document system_cc_shared heap
dma-buf: heaps: system: add system_cc_shared heap for explicitly shared memory
dma-mapping: introduce DMA_ATTR_CC_SHARED for shared memory
mm: cma: Export cma_alloc(), cma_release() and cma_get_name()
dma: contiguous: Export dev_get_cma_area()
dma: contiguous: Make dma_contiguous_default_area static
dma: contiguous: Make dev_get_cma_area() a proper function
dma: contiguous: Turn heap registration logic around
of: reserved_mem: rework fdt_init_reserved_mem_node()
of: reserved_mem: clarify fdt_scan_reserved_mem*() functions
of: reserved_mem: rearrange code a bit
of: reserved_mem: replace CMA quirks by generic methods
of: reserved_mem: switch to ops based OF_DECLARE()
of: reserved_mem: use -ENODEV instead of -ENOENT
of: reserved_mem: remove fdt node from the structure
dma-mapping: fix false kernel-doc comment marker
dma-mapping: Support batch mode for dma_direct_{map,unmap}_sg
dma-mapping: Separate DMA sync issuing and completion waiting
arm64: Provide dcache_inval_poc_nosync helper
arm64: Provide dcache_clean_poc_nosync helper
...
The expression `rpool->resources[index].usage + 1` is computed in int
arithmetic before being assigned to s64 variable `new`. When usage equals
INT_MAX (the default "max" value), the addition overflows to INT_MIN.
This negative value then passes the `new > max` check incorrectly,
allowing a charge that should be rejected and corrupting usage to
negative.
Fix by casting usage to s64 before the addition so the arithmetic is
done in 64-bit.
Fixes: 39d3e7584a ("rdmacg: Added rdma cgroup controller")
Signed-off-by: cuitao <cuitao@kylinos.cn>
Reviewed-by: Michal Koutný <mkoutny@suse.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
A potential race condition exists between pressure write and cgroup file
release regarding the priv member of struct kernfs_open_file, which
triggers the uaf reported in [1].
Consider the following scenario involving execution on two separate CPUs:
CPU0 CPU1
==== ====
vfs_rmdir()
kernfs_iop_rmdir()
cgroup_rmdir()
cgroup_kn_lock_live()
cgroup_destroy_locked()
cgroup_addrm_files()
cgroup_rm_file()
kernfs_remove_by_name()
kernfs_remove_by_name_ns()
vfs_write() __kernfs_remove()
new_sync_write() kernfs_drain()
kernfs_fop_write_iter() kernfs_drain_open_files()
cgroup_file_write() kernfs_release_file()
pressure_write() cgroup_file_release()
ctx = of->priv;
kfree(ctx);
of->priv = NULL;
cgroup_kn_unlock()
cgroup_kn_lock_live()
cgroup_get(cgrp)
cgroup_kn_unlock()
if (ctx->psi.trigger) // here, trigger uaf for ctx, that is of->priv
The cgroup_rmdir() is protected by the cgroup_mutex, it also safeguards
the memory deallocation of of->priv performed within cgroup_file_release().
However, the operations involving of->priv executed within pressure_write()
are not entirely covered by the protection of cgroup_mutex. Consequently,
if the code in pressure_write(), specifically the section handling the
ctx variable executes after cgroup_file_release() has completed, a uaf
vulnerability involving of->priv is triggered.
Therefore, the issue can be resolved by extending the scope of the
cgroup_mutex lock within pressure_write() to encompass all code paths
involving of->priv, thereby properly synchronizing the race condition
occurring between cgroup_file_release() and pressure_write().
And, if an live kn lock can be successfully acquired while executing
the pressure write operation, it indicates that the cgroup deletion
process has not yet reached its final stage; consequently, the priv
pointer within open_file cannot be NULL. Therefore, the operation to
retrieve the ctx value must be moved to a point *after* the live kn
lock has been successfully acquired.
In another situation, specifically after entering cgroup_kn_lock_live()
but before acquiring cgroup_mutex, there exists a different class of
race condition:
CPU0: write memory.pressure CPU1: write cgroup.pressure=0
=========================== =============================
kernfs_fop_write_iter()
kernfs_get_active_of(of)
pressure_write()
cgroup_kn_lock_live(memory.pressure)
cgroup_tryget(cgrp)
kernfs_break_active_protection(kn)
... blocks on cgroup_mutex
cgroup_pressure_write()
cgroup_kn_lock_live(cgroup.pressure)
cgroup_file_show(memory.pressure, false)
kernfs_show(false)
kernfs_drain_open_files()
cgroup_file_release(of)
kfree(ctx)
of->priv = NULL
cgroup_kn_unlock()
... acquires cgroup_mutex
ctx = of->priv; // may now be NULL
if (ctx->psi.trigger) // NULL dereference
Consequently, there is a possibility that of->priv is NULL, the pressure
write needs to check for this.
Now that the scope of the cgroup_mutex has been expanded, the original
explicit cgroup_get/put operations are no longer necessary, this is
because acquiring/releasing the live kn lock inherently executes a
cgroup get/put operation.
[1]
BUG: KASAN: slab-use-after-free in pressure_write+0xa4/0x210 kernel/cgroup/cgroup.c:4011
Call Trace:
pressure_write+0xa4/0x210 kernel/cgroup/cgroup.c:4011
cgroup_file_write+0x36f/0x790 kernel/cgroup/cgroup.c:4311
kernfs_fop_write_iter+0x3b0/0x540 fs/kernfs/file.c:352
Allocated by task 9352:
cgroup_file_open+0x90/0x3a0 kernel/cgroup/cgroup.c:4256
kernfs_fop_open+0x9eb/0xcb0 fs/kernfs/file.c:724
do_dentry_open+0x83d/0x13e0 fs/open.c:949
Freed by task 9353:
cgroup_file_release+0xd6/0x100 kernel/cgroup/cgroup.c:4283
kernfs_release_file fs/kernfs/file.c:764 [inline]
kernfs_drain_open_files+0x392/0x720 fs/kernfs/file.c:834
kernfs_drain+0x470/0x600 fs/kernfs/dir.c:525
Fixes: 0e94682b73 ("psi: introduce psi monitor")
Reported-by: syzbot+33e571025d88efd1312c@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=33e571025d88efd1312c
Tested-by: syzbot+33e571025d88efd1312c@syzkaller.appspotmail.com
Signed-off-by: Edward Adam Davis <eadavis@qq.com>
Reviewed-by: Chen Ridong <chenridong@huaweicloud.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
arena_alloc_pages() accepts a plain int node_id and forwards it through
the entire allocation chain without any bounds checking.
Validate node_id before passing it down the allocation chain in
arena_alloc_pages().
Fixes: 317460317a ("bpf: Introduce bpf_arena.")
Signed-off-by: Puranjay Mohan <puranjay@kernel.org>
Reviewed-by: Emil Tsalapatis <emil@etsalapatis.com>
Link: https://lore.kernel.org/r/20260417152135.1383754-1-puranjay@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
- Add TIMERLAT_ALIGN osnoise option
Add a timer alignment option for timerlat that makes it work like the
cyclictest -A option. timelat creates threads to test the latency of the
kernel. The alignment option will have these threads trigger at the
alignment offsets from each other. Instead of having each thread wake up
at the exact same time, if the alignment is set to "20" each thread will
wake up at 20 microseconds from the previous one.
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Merge tag 'trace-latency-v7.1' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace
Pull tracing latency update from Steven Rostedt:
- Add TIMERLAT_ALIGN osnoise option
Add a timer alignment option for timerlat that makes it work like the
cyclictest -A option. timelat creates threads to test the latency of
the kernel. The alignment option will have these threads trigger at
the alignment offsets from each other. Instead of having each thread
wake up at the exact same time, if the alignment is set to "20" each
thread will wake up at 20 microseconds from the previous one.
* tag 'trace-latency-v7.1' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
tracing/osnoise: Add option to align tlat threads
- Fix printf format warning for bprintf
sunrpc uses a trace_printk() that triggers a printf warning during the
compile. Move the __printf() attribute around for when debugging is not
enabled the warning will go away.
- Remove redundant check for EVENT_FILE_FL_FREED in event_filter_write()
The FREED flag is checked in the call to event_file_file() and then
checked again right afterward, which is unneeded.
- Clean up event_file_file() and event_file_data() helpers
These helper functions played a different role in the past, but now with
eventfs, the READ_ONCE() isn't needed. Simplify the code a bit and also
add a warning to event_file_data() if the file or its data is not present.
- Remove updating file->private_data in tracing open
All access to the file private data is handled by the helper functions,
which do not use file->private_data. Stop updating it on open.
- Show ENUM names in function arguments via BTF in function tracing
When showing the function arguments when func-args option is set for
function tracing, if one of the arguments is found to be an enum, show the
name of the enum instead of its number.
- Add new trace_call__##name() API for tracepoints
Tracepoints are enabled via static_branch() blocks, where when not
enabled, there's only a nop that is in the code where the execution will
just skip over it. When tracing is enabled, the nop is converted to a
direct jump to the tracepoint code. Sometimes more calculations are
required to be performed to update the parameters of the tracepoint. In
this case, trace_##name##_enabled() is called which is a static_branch()
that gets enabled only when the tracepoint is enabled. This allows the
extra calculations to also be skipped by the nop:
if (trace_foo_enabled()) {
x = bar();
trace_foo(x);
}
Where the x=bar() is only performed when foo is enabled. The problem with
this approach is that there's now two static_branch() calls. One for
checking if the tracepoint is enabled, and then again to know if the
tracepoint should be called. The second one is redundant.
Introduce trace_call__foo() that will call the foo() tracepoint directly
without doing a static_branch():
if (trace_foo_enabled()) {
x = bar();
trace_call__foo();
}
- Update various locations to use the new trace_call__##name() API
- Move snapshot code out of trace.c
Cleaning up trace.c to not be a "dump all", move the snapshot code out of
it and into a new trace_snapshot.c file.
- Clean up some "%*.s" to "%*s"
- Allow boot kernel command line options to be called multiple times
Have options like:
ftrace_filter=foo ftrace_filter=bar ftrace_filter=zoo
Equal to:
ftrace_filter=foo,bar,zoo
- Fix ipi_raise event CPU field to be a CPU field
The ipi_raise target_cpus field is defined as a __bitmask(). There is now a
__cpumask() field definition. Update the field to use that.
- Have hist_field_name() use a snprintf() and not a series of strcat()
It's safer to use snprintf() that a series of strcat().
- Fix tracepoint regfunc balancing
A tracepoint can define a "reg" and "unreg" function that gets called
before the tracepoint is enabled, and after it is disabled respectively.
But on error, after the "reg" func is called and the tracepoint is not
enabled, the "unreg" function is not called to tear down what the "reg"
function performed.
- Fix output that shows what histograms are enabled
Event variables are displayed incorrectly in the histogram output.
Instead of "sched.sched_wakeup.$var", it is showing
"$sched.sched_wakeup.var" where the '$' is in the incorrect location.
- Some other simple cleanups.
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Merge tag 'trace-v7.1' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace
Pull tracing updates from Steven Rostedt:
- Fix printf format warning for bprintf
sunrpc uses a trace_printk() that triggers a printf warning during
the compile. Move the __printf() attribute around for when debugging
is not enabled the warning will go away
- Remove redundant check for EVENT_FILE_FL_FREED in
event_filter_write()
The FREED flag is checked in the call to event_file_file() and then
checked again right afterward, which is unneeded
- Clean up event_file_file() and event_file_data() helpers
These helper functions played a different role in the past, but now
with eventfs, the READ_ONCE() isn't needed. Simplify the code a bit
and also add a warning to event_file_data() if the file or its data
is not present
- Remove updating file->private_data in tracing open
All access to the file private data is handled by the helper
functions, which do not use file->private_data. Stop updating it on
open
- Show ENUM names in function arguments via BTF in function tracing
When showing the function arguments when func-args option is set for
function tracing, if one of the arguments is found to be an enum,
show the name of the enum instead of its number
- Add new trace_call__##name() API for tracepoints
Tracepoints are enabled via static_branch() blocks, where when not
enabled, there's only a nop that is in the code where the execution
will just skip over it. When tracing is enabled, the nop is converted
to a direct jump to the tracepoint code. Sometimes more calculations
are required to be performed to update the parameters of the
tracepoint. In this case, trace_##name##_enabled() is called which is
a static_branch() that gets enabled only when the tracepoint is
enabled. This allows the extra calculations to also be skipped by the
nop:
if (trace_foo_enabled()) {
x = bar();
trace_foo(x);
}
Where the x=bar() is only performed when foo is enabled. The problem
with this approach is that there's now two static_branch() calls. One
for checking if the tracepoint is enabled, and then again to know if
the tracepoint should be called. The second one is redundant
Introduce trace_call__foo() that will call the foo() tracepoint
directly without doing a static_branch():
if (trace_foo_enabled()) {
x = bar();
trace_call__foo();
}
- Update various locations to use the new trace_call__##name() API
- Move snapshot code out of trace.c
Cleaning up trace.c to not be a "dump all", move the snapshot code
out of it and into a new trace_snapshot.c file
- Clean up some "%*.s" to "%*s"
- Allow boot kernel command line options to be called multiple times
Have options like:
ftrace_filter=foo ftrace_filter=bar ftrace_filter=zoo
Equal to:
ftrace_filter=foo,bar,zoo
- Fix ipi_raise event CPU field to be a CPU field
The ipi_raise target_cpus field is defined as a __bitmask(). There is
now a __cpumask() field definition. Update the field to use that
- Have hist_field_name() use a snprintf() and not a series of strcat()
It's safer to use snprintf() that a series of strcat()
- Fix tracepoint regfunc balancing
A tracepoint can define a "reg" and "unreg" function that gets called
before the tracepoint is enabled, and after it is disabled
respectively. But on error, after the "reg" func is called and the
tracepoint is not enabled, the "unreg" function is not called to tear
down what the "reg" function performed
- Fix output that shows what histograms are enabled
Event variables are displayed incorrectly in the histogram output
Instead of "sched.sched_wakeup.$var", it is showing
"$sched.sched_wakeup.var" where the '$' is in the incorrect location
- Some other simple cleanups
* tag 'trace-v7.1' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: (24 commits)
selftests/ftrace: Add test case for fully-qualified variable references
tracing: Fix fully-qualified variable reference printing in histograms
tracepoint: balance regfunc() on func_add() failure in tracepoint_add_func()
tracing: Rebuild full_name on each hist_field_name() call
tracing: Report ipi_raise target CPUs as cpumask
tracing: Remove duplicate latency_fsnotify() stub
tracing: Preserve repeated trace_trigger boot parameters
tracing: Append repeated boot-time tracing parameters
tracing: Remove spurious default precision from show_event_trigger/filter formats
cpufreq: Use trace_call__##name() at guarded tracepoint call sites
tracing: Remove tracing_alloc_snapshot() when snapshot isn't defined
tracing: Move snapshot code out of trace.c and into trace_snapshot.c
mm: damon: Use trace_call__##name() at guarded tracepoint call sites
btrfs: Use trace_call__##name() at guarded tracepoint call sites
spi: Use trace_call__##name() at guarded tracepoint call sites
i2c: Use trace_call__##name() at guarded tracepoint call sites
kernel: Use trace_call__##name() at guarded tracepoint call sites
tracepoint: Add trace_call__##name() API
tracing: trace_mmap.h: fix a kernel-doc warning
tracing: Pretty-print enum parameters in function arguments
...
- fprobe: do not zero out unused fgraph_data. This removes unneeded
memset of fgraph_data in fprobe entry handler.
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Merge tag 'probes-v7.1' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace
Pull fprobe update from Masami Hiramatsu:
- do not zero out unused fgraph_data. This removes unneeded memset of
fgraph_data in fprobe entry handler.
* tag 'probes-v7.1' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
tracing: fprobe: do not zero out unused fgraph_data
- Add support for tracing in the standalone EL2 hypervisor code, which
should help both debugging and performance analysis. This uses the
new infrastructure for 'remote' trace buffers that can be exposed
by non-kernel entities such as firmware, and which came through the
tracing tree.
- Add support for GICv5 Per Processor Interrupts (PPIs), as the starting
point for supporting the new GIC architecture in KVM.
- Finally add support for pKVM protected guests, where pages are unmapped
from the host as they are faulted into the guest and can be shared back
from the guest using pKVM hypercalls. Protected guests are created
using a new machine type identifier. As the elusive guestmem has not
yet delivered on its promises, anonymous memory is also supported.
This is only a first step towards full isolation from the host; for
example, the CPU register state and DMA accesses are not yet isolated.
Because this does not really yet bring fully what it promises, it is
hidden behind CONFIG_ARM_PKVM_GUEST + 'kvm-arm.mode=protected', and
also triggers TAINT_USER when a VM is created. Caveat emptor.
- Rework the dreaded user_mem_abort() function to make it more
maintainable, reducing the amount of state being exposed to the
various helpers and rendering a substantial amount of state immutable.
- Expand the Stage-2 page table dumper to support NV shadow page tables
on a per-VM basis.
- Tidy up the pKVM PSCI proxy code to be slightly less hard to follow.
- Fix both SPE and TRBE in non-VHE configurations so that they do not
generate spurious, out of context table walks that ultimately lead
to very bad HW lockups.
- A small set of patches fixing the Stage-2 MMU freeing in error cases.
- Tighten-up accepted SMC immediate value to be only #0 for host
SMCCC calls.
- The usual cleanups and other selftest churn.
LoongArch:
- Use CSR_CRMD_PLV for kvm_arch_vcpu_in_kernel().
- Add DMSINTC irqchip in kernel support.
RISC-V:
- Fix steal time shared memory alignment checks
- Fix vector context allocation leak
- Fix array out-of-bounds in pmu_ctr_read() and pmu_fw_ctr_read_hi()
- Fix double-free of sdata in kvm_pmu_clear_snapshot_area()
- Fix integer overflow in kvm_pmu_validate_counter_mask()
- Fix shift-out-of-bounds in make_xfence_request()
- Fix lost write protection on huge pages during dirty logging
- Split huge pages during fault handling for dirty logging
- Skip CSR restore if VCPU is reloaded on the same core
- Implement kvm_arch_has_default_irqchip() for KVM selftests
- Factored-out ISA checks into separate sources
- Added hideleg to struct kvm_vcpu_config
- Factored-out VCPU config into separate sources
- Support configuration of per-VM HGATP mode from KVM user space
s390:
- Support for ESA (31-bit) guests inside nested hypervisors.
- Remove restriction on memslot alignment, which is not needed anymore with
the new gmap code.
- Fix LPSW/E to update the bear (which of course is the breaking event
address register).
x86:
- Shut up various UBSAN warnings on reading module parameter before they
were initialized.
- Don't zero-allocate page tables that are used for splitting hugepages in
the TDP MMU, as KVM is guaranteed to set all SPTEs in the page table and
thus write all bytes.
- As an optimization, bail early when trying to unsync 4KiB mappings if the
target gfn can just be mapped with a 2MiB hugepage.
x86 generic:
- Copy single-chunk MMIO write values into struct kvm_vcpu (more precisely
struct kvm_mmio_fragment) to fix use-after-free stack bugs where KVM
would dereference stack pointer after an exit to userspace.
- Clean up and comment the emulated MMIO code to try to make it easier to
maintain (not necessarily "easy", but "easier").
- Move VMXON+VMXOFF and EFER.SVME toggling out of KVM (not *all* of VMX
and SVM enabling) as it is needed for trusted I/O.
- Advertise support for AVX512 Bit Matrix Multiply (BMM) instructions
- Immediately fail the build if a required #define is missing in one of
KVM's headers that is included multiple times.
- Reject SET_GUEST_DEBUG with -EBUSY if there's an already injected
exception, mostly to prevent syzkaller from abusing the uAPI to
trigger WARNs, but also because it can help prevent userspace from
unintentionally crashing the VM.
- Exempt SMM from CPUID faulting on Intel, as per the spec.
- Misc hardening and cleanup changes.
x86 (AMD):
- Fix and optimize IRQ window inhibit handling for AVIC; make it per-vCPU
so that KVM doesn't prematurely re-enable AVIC if multiple
vCPUs have to-be-injected IRQs.
- Clean up and optimize the OSVW handling, avoiding a bug in which KVM would
overwrite state when enabling virtualization on multiple CPUs in parallel.
This should not be a problem because OSVW should usually be the same for
all CPUs.
- Drop a WARN in KVM_MEMORY_ENCRYPT_REG_REGION where KVM complains about a
"too large" size based purely on user input.
- Clean up and harden the pinning code for KVM_MEMORY_ENCRYPT_REG_REGION.
- Disallow synchronizing a VMSA of an already-launched/encrypted vCPU, as
doing so for an SNP guest will crash the host due to an RMP violation
page fault.
- Overhaul KVM's APIs for detecting SEV+ guests so that VM-scoped queries
are required to hold kvm->lock, and enforce it by lockdep. Fix various
bugs where sev_guest() was not ensured to be stable for the whole
duration of a function or ioctl.
- Convert a pile of kvm->lock SEV code to guard().
- Play nicer with userspace that does not enable KVM_CAP_EXCEPTION_PAYLOAD,
for which KVM needs to set CR2 and DR6 as a response to ioctls such as
KVM_GET_VCPU_EVENTS (even if the payload would end up in EXITINFO2
rather than CR2, for example). Only set CR2 and DR6 when consumption of
the payload is imminent, but on the other hand force delivery of the
payload in all paths where userspace retrieves CR2 or DR6.
- Use vcpu->arch.cr2 when updating vmcb12's CR2 on nested #VMEXIT instead
of vmcb02->save.cr2. The value is out of sync after a save/restore
or after a #PF is injected into L2.
- Fix a class of nSVM bugs where some fields written by the CPU are not
synchronized from vmcb02 to cached vmcb12 after VMRUN, and so are not
up-to-date when saved by KVM_GET_NESTED_STATE.
- Fix a class of bugs where the ordering between KVM_SET_NESTED_STATE and
KVM_SET_{S}REGS could cause vmcb02 to be incorrectly initialized after
save+restore.
- Add a variety of missing nSVM consistency checks.
- Fix several bugs where KVM failed to correctly update VMCB fields on
nested #VMEXIT.
- Fix several bugs where KVM failed to correctly synthesize #UD or #GP for
SVM-related instructions.
- Add support for save+restore of virtualized LBRs (on SVM).
- Refactor various helpers and macros to improve clarity and (hopefully)
make the code easier to maintain.
- Aggressively sanitize fields when copying from vmcb12, to guard against
unintentionally allowing L1 to utilize yet-to-be-defined features.
- Fix several bugs where KVM botched rAX legality checks when emulating SVM
instructions. There are remaining issues in that KVM doesn't handle size
prefix overrides for 64-bit guests.
- Fail emulation of VMRUN/VMLOAD/VMSAVE if mapping vmcb12 fails instead of
somewhat arbitrarily synthesizing #GP (i.e. don't double down on AMD's
architectural but sketchy behavior of generating #GP for "unsupported"
addresses).
- Cache all used vmcb12 fields to further harden against TOCTOU bugs.
x86 (Intel):
- Drop obsolete branch hint prefixes from the VMX instruction macros.
- Use ASM_INPUT_RM() in __vmcs_writel() to coerce clang into using a
register input when appropriate.
- Code cleanups.
guest_memfd:
- Don't mark guest_memfd folios as accessed, as guest_memfd doesn't support
reclaim, the memory is unevictable, and there is no storage to write
back to.
LoongArch selftests:
- Add KVM PMU test cases
s390 selftests:
- Enable more memory selftests.
x86 selftests:
- Add support for Hygon CPUs in KVM selftests.
- Fix a bug in the MSR test where it would get false failures on AMD/Hygon
CPUs with exactly one of RDPID or RDTSCP.
- Add an MADV_COLLAPSE testcase for guest_memfd as a regression test for a
bug where the kernel would attempt to collapse guest_memfd folios against
KVM's will.
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Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm
Pull kvm updates from Paolo Bonzini:
"Arm:
- Add support for tracing in the standalone EL2 hypervisor code,
which should help both debugging and performance analysis. This
uses the new infrastructure for 'remote' trace buffers that can be
exposed by non-kernel entities such as firmware, and which came
through the tracing tree
- Add support for GICv5 Per Processor Interrupts (PPIs), as the
starting point for supporting the new GIC architecture in KVM
- Finally add support for pKVM protected guests, where pages are
unmapped from the host as they are faulted into the guest and can
be shared back from the guest using pKVM hypercalls. Protected
guests are created using a new machine type identifier. As the
elusive guestmem has not yet delivered on its promises, anonymous
memory is also supported
This is only a first step towards full isolation from the host; for
example, the CPU register state and DMA accesses are not yet
isolated. Because this does not really yet bring fully what it
promises, it is hidden behind CONFIG_ARM_PKVM_GUEST +
'kvm-arm.mode=protected', and also triggers TAINT_USER when a VM is
created. Caveat emptor
- Rework the dreaded user_mem_abort() function to make it more
maintainable, reducing the amount of state being exposed to the
various helpers and rendering a substantial amount of state
immutable
- Expand the Stage-2 page table dumper to support NV shadow page
tables on a per-VM basis
- Tidy up the pKVM PSCI proxy code to be slightly less hard to
follow
- Fix both SPE and TRBE in non-VHE configurations so that they do not
generate spurious, out of context table walks that ultimately lead
to very bad HW lockups
- A small set of patches fixing the Stage-2 MMU freeing in error
cases
- Tighten-up accepted SMC immediate value to be only #0 for host
SMCCC calls
- The usual cleanups and other selftest churn
LoongArch:
- Use CSR_CRMD_PLV for kvm_arch_vcpu_in_kernel()
- Add DMSINTC irqchip in kernel support
RISC-V:
- Fix steal time shared memory alignment checks
- Fix vector context allocation leak
- Fix array out-of-bounds in pmu_ctr_read() and pmu_fw_ctr_read_hi()
- Fix double-free of sdata in kvm_pmu_clear_snapshot_area()
- Fix integer overflow in kvm_pmu_validate_counter_mask()
- Fix shift-out-of-bounds in make_xfence_request()
- Fix lost write protection on huge pages during dirty logging
- Split huge pages during fault handling for dirty logging
- Skip CSR restore if VCPU is reloaded on the same core
- Implement kvm_arch_has_default_irqchip() for KVM selftests
- Factored-out ISA checks into separate sources
- Added hideleg to struct kvm_vcpu_config
- Factored-out VCPU config into separate sources
- Support configuration of per-VM HGATP mode from KVM user space
s390:
- Support for ESA (31-bit) guests inside nested hypervisors
- Remove restriction on memslot alignment, which is not needed
anymore with the new gmap code
- Fix LPSW/E to update the bear (which of course is the breaking
event address register)
x86:
- Shut up various UBSAN warnings on reading module parameter before
they were initialized
- Don't zero-allocate page tables that are used for splitting
hugepages in the TDP MMU, as KVM is guaranteed to set all SPTEs in
the page table and thus write all bytes
- As an optimization, bail early when trying to unsync 4KiB mappings
if the target gfn can just be mapped with a 2MiB hugepage
x86 generic:
- Copy single-chunk MMIO write values into struct kvm_vcpu (more
precisely struct kvm_mmio_fragment) to fix use-after-free stack
bugs where KVM would dereference stack pointer after an exit to
userspace
- Clean up and comment the emulated MMIO code to try to make it
easier to maintain (not necessarily "easy", but "easier")
- Move VMXON+VMXOFF and EFER.SVME toggling out of KVM (not *all* of
VMX and SVM enabling) as it is needed for trusted I/O
- Advertise support for AVX512 Bit Matrix Multiply (BMM) instructions
- Immediately fail the build if a required #define is missing in one
of KVM's headers that is included multiple times
- Reject SET_GUEST_DEBUG with -EBUSY if there's an already injected
exception, mostly to prevent syzkaller from abusing the uAPI to
trigger WARNs, but also because it can help prevent userspace from
unintentionally crashing the VM
- Exempt SMM from CPUID faulting on Intel, as per the spec
- Misc hardening and cleanup changes
x86 (AMD):
- Fix and optimize IRQ window inhibit handling for AVIC; make it
per-vCPU so that KVM doesn't prematurely re-enable AVIC if multiple
vCPUs have to-be-injected IRQs
- Clean up and optimize the OSVW handling, avoiding a bug in which
KVM would overwrite state when enabling virtualization on multiple
CPUs in parallel. This should not be a problem because OSVW should
usually be the same for all CPUs
- Drop a WARN in KVM_MEMORY_ENCRYPT_REG_REGION where KVM complains
about a "too large" size based purely on user input
- Clean up and harden the pinning code for KVM_MEMORY_ENCRYPT_REG_REGION
- Disallow synchronizing a VMSA of an already-launched/encrypted
vCPU, as doing so for an SNP guest will crash the host due to an
RMP violation page fault
- Overhaul KVM's APIs for detecting SEV+ guests so that VM-scoped
queries are required to hold kvm->lock, and enforce it by lockdep.
Fix various bugs where sev_guest() was not ensured to be stable for
the whole duration of a function or ioctl
- Convert a pile of kvm->lock SEV code to guard()
- Play nicer with userspace that does not enable
KVM_CAP_EXCEPTION_PAYLOAD, for which KVM needs to set CR2 and DR6
as a response to ioctls such as KVM_GET_VCPU_EVENTS (even if the
payload would end up in EXITINFO2 rather than CR2, for example).
Only set CR2 and DR6 when consumption of the payload is imminent,
but on the other hand force delivery of the payload in all paths
where userspace retrieves CR2 or DR6
- Use vcpu->arch.cr2 when updating vmcb12's CR2 on nested #VMEXIT
instead of vmcb02->save.cr2. The value is out of sync after a
save/restore or after a #PF is injected into L2
- Fix a class of nSVM bugs where some fields written by the CPU are
not synchronized from vmcb02 to cached vmcb12 after VMRUN, and so
are not up-to-date when saved by KVM_GET_NESTED_STATE
- Fix a class of bugs where the ordering between KVM_SET_NESTED_STATE
and KVM_SET_{S}REGS could cause vmcb02 to be incorrectly
initialized after save+restore
- Add a variety of missing nSVM consistency checks
- Fix several bugs where KVM failed to correctly update VMCB fields
on nested #VMEXIT
- Fix several bugs where KVM failed to correctly synthesize #UD or
#GP for SVM-related instructions
- Add support for save+restore of virtualized LBRs (on SVM)
- Refactor various helpers and macros to improve clarity and
(hopefully) make the code easier to maintain
- Aggressively sanitize fields when copying from vmcb12, to guard
against unintentionally allowing L1 to utilize yet-to-be-defined
features
- Fix several bugs where KVM botched rAX legality checks when
emulating SVM instructions. There are remaining issues in that KVM
doesn't handle size prefix overrides for 64-bit guests
- Fail emulation of VMRUN/VMLOAD/VMSAVE if mapping vmcb12 fails
instead of somewhat arbitrarily synthesizing #GP (i.e. don't double
down on AMD's architectural but sketchy behavior of generating #GP
for "unsupported" addresses)
- Cache all used vmcb12 fields to further harden against TOCTOU bugs
x86 (Intel):
- Drop obsolete branch hint prefixes from the VMX instruction macros
- Use ASM_INPUT_RM() in __vmcs_writel() to coerce clang into using a
register input when appropriate
- Code cleanups
guest_memfd:
- Don't mark guest_memfd folios as accessed, as guest_memfd doesn't
support reclaim, the memory is unevictable, and there is no storage
to write back to
LoongArch selftests:
- Add KVM PMU test cases
s390 selftests:
- Enable more memory selftests
x86 selftests:
- Add support for Hygon CPUs in KVM selftests
- Fix a bug in the MSR test where it would get false failures on
AMD/Hygon CPUs with exactly one of RDPID or RDTSCP
- Add an MADV_COLLAPSE testcase for guest_memfd as a regression test
for a bug where the kernel would attempt to collapse guest_memfd
folios against KVM's will"
* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (373 commits)
KVM: x86: use inlines instead of macros for is_sev_*guest
x86/virt: Treat SVM as unsupported when running as an SEV+ guest
KVM: SEV: Goto an existing error label if charging misc_cg for an ASID fails
KVM: SVM: Move lock-protected allocation of SEV ASID into a separate helper
KVM: SEV: use mutex guard in snp_handle_guest_req()
KVM: SEV: use mutex guard in sev_mem_enc_unregister_region()
KVM: SEV: use mutex guard in sev_mem_enc_ioctl()
KVM: SEV: use mutex guard in snp_launch_update()
KVM: SEV: Assert that kvm->lock is held when querying SEV+ support
KVM: SEV: Document that checking for SEV+ guests when reclaiming memory is "safe"
KVM: SEV: Hide "struct kvm_sev_info" behind CONFIG_KVM_AMD_SEV=y
KVM: SEV: WARN on unhandled VM type when initializing VM
KVM: LoongArch: selftests: Add PMU overflow interrupt test
KVM: LoongArch: selftests: Add basic PMU event counting test
KVM: LoongArch: selftests: Add cpucfg read/write helpers
LoongArch: KVM: Add DMSINTC inject msi to vCPU
LoongArch: KVM: Add DMSINTC device support
LoongArch: KVM: Make vcpu_is_preempted() as a macro rather than function
LoongArch: KVM: Move host CSR_GSTAT save and restore in context switch
LoongArch: KVM: Move host CSR_EENTRY save and restore in context switch
...
Total patches: 126
Reviews/patch: 0.92
Reviewed rate: 76%
- The 2 patch series "pid: make sub-init creation retryable" from Oleg
Nesterov increases the robustness of our creation of init in a new
namespace. By clearing away some historical cruft which is no longer
needed. Also some documentation fixups are provided.
- The 2 patch series "selftests/fchmodat2: Error handling and general"
from Mark Brown has a fixup and a cleanup for the fchmodat2() syscall
selftest.
- The 3 patch series "lib: polynomial: Move to math/ and clean up" from
Andy Shevchenko does as advertised.
- The 3 patch series "hung_task: Provide runtime reset interface for
hung task detector" from Aaron Tomlin gives administrators the ability
to zero out /proc/sys/kernel/hung_task_detect_count.
- The 2 patch series "tools/getdelays: use the static UAPI headers from
tools/include/uapi" from Thomas Weißschuh teaches getdelays to use the
in-kernel UAPI headers rather than the system-provided ones.
- The 5 patch series "watchdog/hardlockup: Improvements to hardlockup"
from Mayank Rungta provides several cleanups and fixups to the
hardlockup detector code and its documentation.
- The 2 patch series "lib/bch: fix undefined behavior from signed
left-shifts" from Josh Law provides a couple of small/theoretical fixes
in the bch code.
- The 2 patch series "ocfs2/dlm: fix two bugs in dlm_match_regions()"
from Junrui Luo does what is claims.
- The 27 patch series "cleanup the RAID5 XOR library" from Christoph
Hellwig is a quite far-reaching cleanup to this code. I can't do better
than to quote Christoph:
The XOR library used for the RAID5 parity is a bit of a mess right
now. The main file sits in crypto/ despite not being cryptography and
not using the crypto API, with the generic implementations sitting in
include/asm-generic and the arch implementations sitting in an asm/
header in theory. The latter doesn't work for many cases, so
architectures often build the code directly into the core kernel, or
create another module for the architecture code.
Change this to a single module in lib/ that also contains the
architecture optimizations, similar to the library work Eric Biggers
has done for the CRC and crypto libraries later. After that it
changes to better calling conventions that allow for smarter
architecture implementations (although none is contained here yet),
and uses static_call to avoid indirection function call overhead.
- The 2 patch series "lib/list_sort: Clean up list_sort() scheduling
workarounds" from Kuan-Wei Chiu cleans up this library code by removing
a hacky thing which was added for UBIFS, which UBIFS doesn't actually
need.
- The 5 patch series "Fix bugs in extract_iter_to_sg()" from Christian
Ehrhardt fixes a few bugs in the scatterlist code, adds in-kernel tests
for the now-fixed bugs and fixes a leak in the test itself.
- The 3 patch series "kdump: Enable LUKS-encrypted dump target support
in ARM64 and PowerPC" from Coiby Xu eenables support of the
LUKS-encrypted device dump target on arm64 and powerpc.
- The 4 patch series "ocfs2: consolidate extent list validation into
block read callbacks" from Joseph Qi addresses ocfs2's validation of
extent list fields - cleanup, simplification, robustness. (Kernel test
robot loves mounting corrupted fs images!)
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Merge tag 'mm-nonmm-stable-2026-04-15-04-20' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Pull non-MM updates from Andrew Morton:
- "pid: make sub-init creation retryable" (Oleg Nesterov)
Make creation of init in a new namespace more robust by clearing away
some historical cruft which is no longer needed. Also some
documentation fixups
- "selftests/fchmodat2: Error handling and general" (Mark Brown)
Fix and a cleanup for the fchmodat2() syscall selftest
- "lib: polynomial: Move to math/ and clean up" (Andy Shevchenko)
- "hung_task: Provide runtime reset interface for hung task detector"
(Aaron Tomlin)
Give administrators the ability to zero out
/proc/sys/kernel/hung_task_detect_count
- "tools/getdelays: use the static UAPI headers from
tools/include/uapi" (Thomas Weißschuh)
Teach getdelays to use the in-kernel UAPI headers rather than the
system-provided ones
- "watchdog/hardlockup: Improvements to hardlockup" (Mayank Rungta)
Several cleanups and fixups to the hardlockup detector code and its
documentation
- "lib/bch: fix undefined behavior from signed left-shifts" (Josh Law)
A couple of small/theoretical fixes in the bch code
- "ocfs2/dlm: fix two bugs in dlm_match_regions()" (Junrui Luo)
- "cleanup the RAID5 XOR library" (Christoph Hellwig)
A quite far-reaching cleanup to this code. I can't do better than to
quote Christoph:
"The XOR library used for the RAID5 parity is a bit of a mess right
now. The main file sits in crypto/ despite not being cryptography
and not using the crypto API, with the generic implementations
sitting in include/asm-generic and the arch implementations
sitting in an asm/ header in theory. The latter doesn't work for
many cases, so architectures often build the code directly into
the core kernel, or create another module for the architecture
code.
Change this to a single module in lib/ that also contains the
architecture optimizations, similar to the library work Eric
Biggers has done for the CRC and crypto libraries later. After
that it changes to better calling conventions that allow for
smarter architecture implementations (although none is contained
here yet), and uses static_call to avoid indirection function call
overhead"
- "lib/list_sort: Clean up list_sort() scheduling workarounds"
(Kuan-Wei Chiu)
Clean up this library code by removing a hacky thing which was added
for UBIFS, which UBIFS doesn't actually need
- "Fix bugs in extract_iter_to_sg()" (Christian Ehrhardt)
Fix a few bugs in the scatterlist code, add in-kernel tests for the
now-fixed bugs and fix a leak in the test itself
- "kdump: Enable LUKS-encrypted dump target support in ARM64 and
PowerPC" (Coiby Xu)
Enable support of the LUKS-encrypted device dump target on arm64 and
powerpc
- "ocfs2: consolidate extent list validation into block read callbacks"
(Joseph Qi)
Cleanup, simplify, and make more robust ocfs2's validation of extent
list fields (Kernel test robot loves mounting corrupted fs images!)
* tag 'mm-nonmm-stable-2026-04-15-04-20' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (127 commits)
ocfs2: validate group add input before caching
ocfs2: validate bg_bits during freefrag scan
ocfs2: fix listxattr handling when the buffer is full
doc: watchdog: fix typos etc
update Sean's email address
ocfs2: use get_random_u32() where appropriate
ocfs2: split transactions in dio completion to avoid credit exhaustion
ocfs2: remove redundant l_next_free_rec check in __ocfs2_find_path()
ocfs2: validate extent block list fields during block read
ocfs2: remove empty extent list check in ocfs2_dx_dir_lookup_rec()
ocfs2: validate dx_root extent list fields during block read
ocfs2: fix use-after-free in ocfs2_fault() when VM_FAULT_RETRY
ocfs2: handle invalid dinode in ocfs2_group_extend
.get_maintainer.ignore: add Askar
ocfs2: validate bg_list extent bounds in discontig groups
checkpatch: exclude forward declarations of const structs
tools/accounting: handle truncated taskstats netlink messages
taskstats: set version in TGID exit notifications
ocfs2/heartbeat: fix slot mapping rollback leaks on error paths
arm64,ppc64le/kdump: pass dm-crypt keys to kdump kernel
...
bpf_bprintf_prepare() only needs ASCII parsing for conversion
specifiers. Plain text can safely carry bytes >= 0x80, so allow
UTF-8 literals outside '%' sequences while keeping ASCII control
bytes rejected and format specifiers ASCII-only.
This keeps existing parsing rules for format directives unchanged,
while allowing helpers such as bpf_trace_printk() to emit UTF-8
literal text.
Update test_snprintf_negative() in the same commit so selftests keep
matching the new plain-text vs format-specifier split during bisection.
Fixes: 48cac3f4a9 ("bpf: Implement formatted output helpers with bstr_printf")
Signed-off-by: Yihan Ding <dingyihan@uniontech.com>
Acked-by: Paul Chaignon <paul.chaignon@gmail.com>
Link: https://lore.kernel.org/r/20260416120142.1420646-2-dingyihan@uniontech.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Commit ab6c637ad0 ("bpf: Fix a bpf_kptr_xchg() issue with local
kptr") refactored map_kptr_match_type() to branch on btf_is_kernel()
before checking base_type(). A scalar register stored into a kptr
slot has no btf, so the btf_is_kernel(reg->btf) call dereferences
NULL.
Move the base_type() != PTR_TO_BTF_ID guard before any reg->btf
access.
Fixes: ab6c637ad0 ("bpf: Fix a bpf_kptr_xchg() issue with local kptr")
Reported-by: Hiker Cl <clhiker365@gmail.com>
Closes: https://bugzilla.kernel.org/show_bug.cgi?id=221372
Signed-off-by: Mykyta Yatsenko <yatsenko@meta.com>
Acked-by: Paul Chaignon <paul.chaignon@gmail.com>
Link: https://lore.kernel.org/r/20260416-kptr_crash-v1-1-5589356584b4@meta.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
The prevention mechanism against timer interrupt starvation missed to reset
the next_event_forced flag in a couple of places:
- When the clock event state changes. That can cause the flag to be
stale over a shutdown/startup sequence
- When a non-forced event is armed, which then prevents rearming before
that event. If that event is far out in the future this will cause
missed timer interrupts.
- In the suspend wakeup handler.
That led to stalls which have been reported by several people.
Add the missing resets, which fixes the problems for the reporters.
Fixes: d6e152d905 ("clockevents: Prevent timer interrupt starvation")
Reported-by: Hanabishi <i.r.e.c.c.a.k.u.n+kernel.org@gmail.com>
Reported-by: Eric Naim <dnaim@cachyos.org>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Tested-by: Hanabishi <i.r.e.c.c.a.k.u.n+kernel.org@gmail.com>
Tested-by: Eric Naim <dnaim@cachyos.org>
Cc: stable@vger.kernel.org
Closes: https://lore.kernel.org/68d1e9ac-2780-4be3-8ee3-0788062dd3a4@gmail.com
Link: https://patch.msgid.link/87340xfeje.ffs@tglx
Add an option called TIMERLAT_ALIGN to osnoise/options, together with a
corresponding setting osnoise/timerlat_align_us.
This option sets the alignment of wakeup times between different
timerlat threads, similarly to cyclictest's -A/--aligned option. If
TIMERLAT_ALIGN is set, the first thread that reaches the first cycle
records its first wake-up time. Each following thread sets its first
wake-up time to a fixed offset from the recorded time, and increments
it by the same offset.
Example:
osnoise/timerlat_period is set to 1000, osnoise/timerlat_align_us is
set to 20. There are four threads, on CPUs 1 to 4.
- CPU 4 enters first cycle first. The current time is 20000us, so
the wake-up of the first cycle is set to 21000us. This time is recorded.
- CPU 2 enter first cycle next. It reads the recorded time, increments
it to 21020us, and uses this value as its own wake-up time for the first
cycle.
- CPU 3 enters first cycle next. It reads the recorded time, increments
it to 21040 us, and uses the value as its own wake-up time.
- CPU 1 proceeds analogically.
In each next cycle, the wake-up time (called "absolute period" in
timerlat code) is incremented by the (relative) period of 1000us. Thus,
the wake-ups in the following cycles (provided the times are reached and
not in the past) will be as follows:
CPU 1 CPU 2 CPU 3 CPU 4
21080us 21020us 21040us 21000us
22080us 22020us 22040us 22000us
... ... ... ...
Even if any cycle is skipped due to e.g. the first cycle calculation
happening later, the alignment stays in place.
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: John Kacur <jkacur@redhat.com>
Cc: Luis Goncalves <lgoncalv@redhat.com>
Cc: Costa Shulyupin <costa.shul@redhat.com>
Link: https://patch.msgid.link/20260416115942.544032-1-tglozar@redhat.com
Signed-off-by: Tomas Glozar <tglozar@redhat.com>
Reviewed-by: Wander Lairson Costa <wander@redhat.com>
Reviewed-by: Crystal Wood <crwood@redhat.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Introduce helper bpf_insn_is_indirect_target to check whether a BPF
instruction is an indirect jump target.
Since the verifier knows which instructions are indirect jump targets,
add a new flag indirect_target to struct bpf_insn_aux_data to mark
them. The verifier sets this flag when verifying an indirect jump target
instruction, and the helper checks the flag to determine whether an
instruction is an indirect jump target.
Reviewed-by: Anton Protopopov <a.s.protopopov@gmail.com> #v8
Reviewed-by: Emil Tsalapatis <emil@etsalapatis.com> #v12
Signed-off-by: Xu Kuohai <xukuohai@huawei.com>
Link: https://lore.kernel.org/r/20260416064341.151802-4-xukuohai@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Pass bpf_verifier_env to bpf_int_jit_compile(). The follow-up patch will
use env->insn_aux_data in the JIT stage to detect indirect jump targets.
Since bpf_prog_select_runtime() can be called by cbpf and lib/test_bpf.c
code without verifier, introduce helper __bpf_prog_select_runtime()
to accept the env parameter.
Remove the call to bpf_prog_select_runtime() in bpf_prog_load(), and
switch to call __bpf_prog_select_runtime() in the verifier, with env
variable passed. The original bpf_prog_select_runtime() is preserved for
cbpf and lib/test_bpf.c, where env is NULL.
Now all constants blinding calls are moved into the verifier, except
the cbpf and lib/test_bpf.c cases. The instructions arrays are adjusted
by bpf_patch_insn_data() function for normal cases, so there is no need
to call adjust_insn_arrays() in bpf_jit_blind_constants(). Remove it.
Reviewed-by: Anton Protopopov <a.s.protopopov@gmail.com> # v8
Reviewed-by: Emil Tsalapatis <emil@etsalapatis.com> # v12
Acked-by: Hengqi Chen <hengqi.chen@gmail.com> # v14
Signed-off-by: Xu Kuohai <xukuohai@huawei.com>
Link: https://lore.kernel.org/r/20260416064341.151802-3-xukuohai@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
During the JIT stage, constants blinding rewrites instructions but only
rewrites the private instruction copy of the JITed subprog, leaving the
global env->prog->insnsi and env->insn_aux_data untouched. This causes a
mismatch between subprog instructions and the global state, making it
difficult to use the global data in the JIT.
To avoid this mismatch, and given that all arch-specific JITs already
support constants blinding, move it to the generic verifier code, and
switch to rewrite the global env->prog->insnsi with the global states
adjusted, as other rewrites in the verifier do.
This removes the constants blinding calls in each JIT, which are largely
duplicated code across architectures.
Since constants blinding is only required for JIT, and there are two
JIT entry functions, jit_subprogs() for BPF programs with multiple
subprogs and bpf_prog_select_runtime() for programs with no subprogs,
move the constants blinding invocation into these two functions.
In the verifier path, bpf_patch_insn_data() is used to keep global
verifier auxiliary data in sync with patched instructions. A key
question is whether this global auxiliary data should be restored
on the failure path.
Besides instructions, bpf_patch_insn_data() adjusts:
- prog->aux->poke_tab
- env->insn_array_maps
- env->subprog_info
- env->insn_aux_data
For prog->aux->poke_tab, it is only used by JIT or only meaningful after
JIT succeeds, so it does not need to be restored on the failure path.
For env->insn_array_maps, when JIT fails, programs using insn arrays
are rejected by bpf_insn_array_ready() due to missing JIT addresses.
Hence, env->insn_array_maps is only meaningful for JIT and does not need
to be restored.
For subprog_info, if jit_subprogs fails and CONFIG_BPF_JIT_ALWAYS_ON
is not enabled, kernel falls back to interpreter. In this case,
env->subprog_info is used to determine subprogram stack depth. So it
must be restored on failure.
For env->insn_aux_data, it is freed by clear_insn_aux_data() at the
end of bpf_check(). Before freeing, clear_insn_aux_data() loops over
env->insn_aux_data to release jump targets recorded in it. The loop
uses env->prog->len as the array length, but this length no longer
matches the actual size of the adjusted env->insn_aux_data array after
constants blinding.
To address it, a simple approach is to keep insn_aux_data as adjusted
after failure, since it will be freed shortly, and record its actual size
for the loop in clear_insn_aux_data(). But since clear_insn_aux_data()
uses the same index to loop over both env->prog->insnsi and env->insn_aux_data,
this approach results in incorrect index for the insnsi array. So an
alternative approach is adopted: clone the original env->insn_aux_data
before blinding and restore it after failure, similar to env->prog.
For classic BPF programs, constants blinding works as before since it
is still invoked from bpf_prog_select_runtime().
Reviewed-by: Anton Protopopov <a.s.protopopov@gmail.com> # v8
Reviewed-by: Hari Bathini <hbathini@linux.ibm.com> # powerpc jit
Reviewed-by: Pu Lehui <pulehui@huawei.com> # riscv jit
Acked-by: Hengqi Chen <hengqi.chen@gmail.com> # loongarch jit
Signed-off-by: Xu Kuohai <xukuohai@huawei.com>
Link: https://lore.kernel.org/r/20260416064341.151802-2-xukuohai@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
- Refactor da_monitor header to share handlers across monitor types
No functional changes, only less code duplication.
- Add Hybrid Automata model class
Add a new model class that extends deterministic automata by adding
constraints on transitions and states. Those constraints can take into
account wall-clock time and as such allow RV monitor to make
assertions on real time. Add documentation and code generation
scripts.
- Add stall monitor as hybrid automaton example
Add a monitor that triggers a violation when a task is stalling as an
example of automaton working with real time variables.
- Convert the opid monitor to a hybrid automaton
The opid monitor can be heavily simplified if written as a hybrid
automaton: instead of tracking preempt and interrupt enable/disable
events, it can just run constraints on the preemption/interrupt
states when events like wakeup and need_resched verify.
- Add support for per-object monitors in DA/HA
Allow writing deterministic and hybrid automata monitors for generic
objects (e.g. any struct), by exploiting a hash table where objects
are saved. This allows to track more than just tasks in RV. For
instance it will be used to track deadline entities in deadline
monitors.
- Add deadline tracepoints and move some deadline utilities
Prepare the ground for deadline monitors by defining events and
exporting helpers.
- Add nomiss deadline monitor
Add first example of deadline monitor asserting all entities complete
before their deadline.
- Improve rvgen error handling
Introduce AutomataError exception class and better handle expected
exceptions while showing a backtrace for unexpected ones.
- Improve python code quality in rvgen
Refactor the rvgen generation scripts to align with python best
practices: use f-strings instead of %, use len() instead of __len__(),
remove semicolons, use context managers for file operations, fix
whitespace violations, extract magic strings into constants, remove
unused imports and methods.
- Fix small bugs in rvgen
The generator scripts presented some corner case bugs: logical error in
validating what a correct dot file looks like, fix an isinstance()
check, enforce a dot file has an initial state, fix type annotations
and typos in comments.
- rvgen refactoring
Refactor automata.py to use iterator-based parsing and handle required
arguments directly in argparse.
- Allow epoll in rtapp-sleep monitor
The epoll_wait call is now rt-friendly so it should be allowed in the
sleep monitor as a valid sleep method.
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Merge tag 'trace-rv-v7.1' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace
Pull runtime verification updates from Steven Rostedt:
- Refactor da_monitor header to share handlers across monitor types
No functional changes, only less code duplication.
- Add Hybrid Automata model class
Add a new model class that extends deterministic automata by adding
constraints on transitions and states. Those constraints can take
into account wall-clock time and as such allow RV monitor to make
assertions on real time. Add documentation and code generation
scripts.
- Add stall monitor as hybrid automaton example
Add a monitor that triggers a violation when a task is stalling as an
example of automaton working with real time variables.
- Convert the opid monitor to a hybrid automaton
The opid monitor can be heavily simplified if written as a hybrid
automaton: instead of tracking preempt and interrupt enable/disable
events, it can just run constraints on the preemption/interrupt
states when events like wakeup and need_resched verify.
- Add support for per-object monitors in DA/HA
Allow writing deterministic and hybrid automata monitors for generic
objects (e.g. any struct), by exploiting a hash table where objects
are saved. This allows to track more than just tasks in RV. For
instance it will be used to track deadline entities in deadline
monitors.
- Add deadline tracepoints and move some deadline utilities
Prepare the ground for deadline monitors by defining events and
exporting helpers.
- Add nomiss deadline monitor
Add first example of deadline monitor asserting all entities complete
before their deadline.
- Improve rvgen error handling
Introduce AutomataError exception class and better handle expected
exceptions while showing a backtrace for unexpected ones.
- Improve python code quality in rvgen
Refactor the rvgen generation scripts to align with python best
practices: use f-strings instead of %, use len() instead of
__len__(), remove semicolons, use context managers for file
operations, fix whitespace violations, extract magic strings into
constants, remove unused imports and methods.
- Fix small bugs in rvgen
The generator scripts presented some corner case bugs: logical error
in validating what a correct dot file looks like, fix an isinstance()
check, enforce a dot file has an initial state, fix type annotations
and typos in comments.
- rvgen refactoring
Refactor automata.py to use iterator-based parsing and handle
required arguments directly in argparse.
- Allow epoll in rtapp-sleep monitor
The epoll_wait call is now rt-friendly so it should be allowed in the
sleep monitor as a valid sleep method.
* tag 'trace-rv-v7.1' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: (32 commits)
rv: Allow epoll in rtapp-sleep monitor
rv/rvgen: fix _fill_states() return type annotation
rv/rvgen: fix unbound loop variable warning
rv/rvgen: enforce presence of initial state
rv/rvgen: extract node marker string to class constant
rv/rvgen: fix isinstance check in Variable.expand()
rv/rvgen: make monitor arguments required in rvgen
rv/rvgen: remove unused __get_main_name method
rv/rvgen: remove unused sys import from dot2c
rv/rvgen: refactor automata.py to use iterator-based parsing
rv/rvgen: use class constant for init marker
rv/rvgen: fix DOT file validation logic error
rv/rvgen: fix PEP 8 whitespace violations
rv/rvgen: fix typos in automata and generator docstring and comments
rv/rvgen: use context managers for file operations
rv/rvgen: remove unnecessary semicolons
rv/rvgen: replace __len__() calls with len()
rv/rvgen: replace % string formatting with f-strings
rv/rvgen: remove bare except clauses in generator
rv/rvgen: introduce AutomataError exception class
...
bpf_jit_subprogs() copies various fields from the main program's aux to
each subprogram's aux, but omits the BPF token. This causes
bpf_prog_kallsyms_add() to fail for subprograms loaded via BPF token,
as bpf_token_capable() falls back to capable() in init_user_ns when
token is NULL.
Copy prog->aux->token to func[i]->aux->token so that subprograms
inherit the same capability delegation as the main program.
Fixes: d79a354975 ("bpf: Consistently use BPF token throughout BPF verifier logic")
Signed-off-by: Tao Chen <ctao@meta.com>
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20260415-subprog-token-fix-v4-1-9bd000e8b068@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
- Add remote buffers for pKVM
pKVM has a hypervisor component that is used to protect the guest from the
host kernel. This hypervisor is a black box to the kernel as the kernel is
to user space. The remote buffers are used to have a memory mapping
between the hypervisor and the kernel where kernel may send commands to
enable tracing within the hypervisor. Then the kernel will read this
memory mapping just like user space can read the memory mapped ring buffer
of the kernel tracing system.
Since the hypervisor only has a single context, it doesn't need to worry
about races between normal context, interrupt context and NMIs like the
kernel does. The ring buffer it uses doesn't need to be as complex. The
remote buffers are a simple version of the ring buffer that works in a
single context. They are still per-CPU and use sub buffers. The data
layout is the same as the kernel's ring buffer to share the same parsing.
Currently, only ARM64 implements pKVM, but there's work to implement it
also in x86. The remote buffer code is separated out from the ARM
implementation so that it can be used in the future by x86.
The ARM64 updates for pKVM is in the ARM/KVM tree and it merged in the
remote buffers of this tree.
- Merge commit f35dbac694 ("ring-buffer: Fix to update per-subbuf entries of persistent ring buffer")`
A fix was merged upstream that some new changes depended on. The upstream
commit was merged into the ring buffer branch to fulfil the dependency.
- Make the backup instance non reusable
The backup instance is a copy of the persistent ring buffer so that the
persistent ring buffer could start recording again without using the data
from the previous boot. The backup isn't for normal tracing. It is made
read-only, and after it is consumed, it is automatically removed.
- Have backup copy persistent instance before it starts recording
To allow the persistent ring buffer to start recording from the kernel
command line commands, move the copy of the backup instance to before the
the command line options start recording.
- Report header_page overwrite field as "char" and not "int'
The rust parser of the header_page file was triggering a warning when it
defined the overwrite variable as "int" but it was only a single byte in
size.
- Fix memory barriers for the trace_buffer CPU mask
When a CPU comes online, the bit is set to allow readers to know that the
CPU buffer is allocated. The bit is set after the allocation is done, and
a smp_wmb() is performed after the allocation and before the setting of
the bit. But instead of adding a smp_rmb() to all readers, since once a
buffer is created for a CPU it is not deleted if that CPU goes offline, so
this allocation is almost always done at boot up before any readers exist.
If for the unlikely case where a CPU comes online for the first time after
the system boot has finished, send an IPI to all CPUs to force the
smp_rmb() for each CPU.
- Show clock function being used in debugging ring buffer data
When the ring buffer checks are enabled and the ring buffer detects an
inconsistency in the times of the invents, print out the clock being used
when the error occurred. There was a very hard to hit bug that would
happen every so often and it ended up being only triggered when the jiffies
clock was being used. If the bug showed the clock being used, it would
have been much easier to find the problem (which was an internal function
was being traced which caused the clock accounting to go off).
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Merge tag 'trace-ringbuffer-v7.1' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace
Pull ring-buffer updates from Steven Rostedt:
- Add remote buffers for pKVM
pKVM has a hypervisor component that is used to protect the guest
from the host kernel. This hypervisor is a black box to the kernel as
the kernel is to user space. The remote buffers are used to have a
memory mapping between the hypervisor and the kernel where kernel may
send commands to enable tracing within the hypervisor. Then the
kernel will read this memory mapping just like user space can read
the memory mapped ring buffer of the kernel tracing system.
Since the hypervisor only has a single context, it doesn't need to
worry about races between normal context, interrupt context and NMIs
like the kernel does. The ring buffer it uses doesn't need to be as
complex. The remote buffers are a simple version of the ring buffer
that works in a single context. They are still per-CPU and use sub
buffers. The data layout is the same as the kernel's ring buffer to
share the same parsing.
Currently, only ARM64 implements pKVM, but there's work to implement
it also in x86. The remote buffer code is separated out from the ARM
implementation so that it can be used in the future by x86.
The ARM64 updates for pKVM is in the ARM/KVM tree and it merged in
the remote buffers of this tree.
- Make the backup instance non reusable
The backup instance is a copy of the persistent ring buffer so that
the persistent ring buffer could start recording again without using
the data from the previous boot. The backup isn't for normal tracing.
It is made read-only, and after it is consumed, it is automatically
removed.
- Have backup copy persistent instance before it starts recording
To allow the persistent ring buffer to start recording from the
kernel command line commands, move the copy of the backup instance to
before the the command line options start recording.
- Report header_page overwrite field as "char" and not "int'
The rust parser of the header_page file was triggering a warning when
it defined the overwrite variable as "int" but it was only a single
byte in size.
- Fix memory barriers for the trace_buffer CPU mask
When a CPU comes online, the bit is set to allow readers to know that
the CPU buffer is allocated. The bit is set after the allocation is
done, and a smp_wmb() is performed after the allocation and before
the setting of the bit. But instead of adding a smp_rmb() to all
readers, since once a buffer is created for a CPU it is not deleted
if that CPU goes offline, so this allocation is almost always done at
boot up before any readers exist.
If for the unlikely case where a CPU comes online for the first time
after the system boot has finished, send an IPI to all CPUs to force
the smp_rmb() for each CPU.
- Show clock function being used in debugging ring buffer data
When the ring buffer checks are enabled and the ring buffer detects
an inconsistency in the times of the invents, print out the clock
being used when the error occurred. There was a very hard to hit bug
that would happen every so often and it ended up being only triggered
when the jiffies clock was being used. If the bug showed the clock
being used, it would have been much easier to find the problem (which
was an internal function was being traced which caused the clock
accounting to go off).
* tag 'trace-ringbuffer-v7.1' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: (26 commits)
ring-buffer: Prevent off-by-one array access in ring_buffer_desc_page()
ring-buffer: Report header_page overwrite as char
tracing: Allow backup to save persistent ring buffer before it starts
tracing/Documentation: Add a section about backup instance
tracing: Remove the backup instance automatically after read
tracing: Make the backup instance non-reusable
ring-buffer: Enforce read ordering of trace_buffer cpumask and buffers
ring-buffer: Show what clock function is used on timestamp errors
tracing: Check for undefined symbols in simple_ring_buffer
tracing: load/unload page callbacks for simple_ring_buffer
Documentation: tracing: Add tracing remotes
tracing: selftests: Add trace remote tests
tracing: Add a trace remote module for testing
tracing: Introduce simple_ring_buffer
ring-buffer: Export buffer_data_page and macros
tracing: Add helpers to create trace remote events
tracing: Add events/ root files to trace remotes
tracing: Add events to trace remotes
tracing: Add init callback to trace remotes
tracing: Add non-consuming read to trace remotes
...
- Speed up ftrace_lookup_symbols() for single lookups
The kallsyms lookup in ftrace_lookup_symbols() does a linear search over
each symbol. This is fine when it must match multiple strings, but when
there's only a single string being searched for, using a binary search is
much more efficient. When a single string is passed in to search, use the
binary search method.
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Merge tag 'ftrace-v7.1' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace
Pull ftrace update from Steven Rostedt:
- Speed up ftrace_lookup_symbols() for single lookups
The kallsyms lookup in ftrace_lookup_symbols() does a linear search
over each symbol. This is fine when it must match multiple strings,
but when there's only a single string being searched for, using a
binary search is much more efficient. When a single string is passed
in to search, use the binary search method.
* tag 'ftrace-v7.1' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
ftrace: Use kallsyms binary search for single-symbol lookup
API:
- Replace crypto_get_default_rng with crypto_stdrng_get_bytes.
- Remove simd skcipher support.
- Allow algorithm types to be disabled when CRYPTO_SELFTESTS is off.
Algorithms:
- Remove CPU-based des/3des acceleration.
- Add test vectors for authenc(hmac(md5),cbc(aes)).
- Add test vectors for authenc(hmac(md5),cbc(des)).
- Add test vectors for authenc(hmac(md5),rfc3686(ctr(aes))).
- Add test vectors for authenc(hmac(sha1),rfc3686(ctr(aes))).
- Add test vectors for authenc(hmac(sha224),rfc3686(ctr(aes))).
- Add test vectors for authenc(hmac(sha256),rfc3686(ctr(aes))).
- Add test vectors for authenc(hmac(sha384),rfc3686(ctr(aes))).
- Add test vectors for authenc(hmac(sha512),rfc3686(ctr(aes))).
- Replace spin lock with mutex in jitterentropy.
Drivers:
- Add authenc algorithms to safexcel.
- Add support for zstd in qat.
- Add wireless mode support for QAT GEN6.
- Add anti-rollback support for QAT GEN6.
- Add support for ctr(aes), gcm(aes), and ccm(aes) in dthev2.
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Merge tag 'v7.1-p1' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6
Pull crypto update from Herbert Xu:
"API:
- Replace crypto_get_default_rng with crypto_stdrng_get_bytes
- Remove simd skcipher support
- Allow algorithm types to be disabled when CRYPTO_SELFTESTS is off
Algorithms:
- Remove CPU-based des/3des acceleration
- Add test vectors for authenc(hmac(md5),cbc({aes,des})) and
authenc(hmac({md5,sha1,sha224,sha256,sha384,sha512}),rfc3686(ctr(aes)))
- Replace spin lock with mutex in jitterentropy
Drivers:
- Add authenc algorithms to safexcel
- Add support for zstd in qat
- Add wireless mode support for QAT GEN6
- Add anti-rollback support for QAT GEN6
- Add support for ctr(aes), gcm(aes), and ccm(aes) in dthev2"
* tag 'v7.1-p1' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6: (129 commits)
crypto: af_alg - use sock_kmemdup in alg_setkey_by_key_serial
crypto: vmx - remove CRYPTO_DEV_VMX from Kconfig
crypto: omap - convert reqctx buffer to fixed-size array
crypto: atmel-sha204a - add Thorsten Blum as maintainer
crypto: atmel-ecc - add Thorsten Blum as maintainer
crypto: qat - fix IRQ cleanup on 6xxx probe failure
crypto: geniv - Remove unused spinlock from struct aead_geniv_ctx
crypto: qce - simplify qce_xts_swapiv()
crypto: hisilicon - Fix dma_unmap_single() direction
crypto: talitos - rename first/last to first_desc/last_desc
crypto: talitos - fix SEC1 32k ahash request limitation
crypto: jitterentropy - replace long-held spinlock with mutex
crypto: hisilicon - remove unused and non-public APIs for qm and sec
crypto: hisilicon/qm - drop redundant variable initialization
crypto: hisilicon/qm - remove else after return
crypto: hisilicon/qm - add const qualifier to info_name in struct qm_cmd_dump_item
crypto: hisilicon - fix the format string type error
crypto: ccree - fix a memory leak in cc_mac_digest()
crypto: qat - add support for zstd
crypto: qat - use swab32 macro
...
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Merge tag 'pci-v7.1-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/pci/pci
Pull pci updates from Bjorn Helgaas:
"Enumeration:
- Allow TLP Processing Hints to be enabled for RCiEPs (George Abraham
P)
- Enable AtomicOps only if we know the Root Port supports them (Gerd
Bayer)
- Don't enable AtomicOps for RCiEPs since none of them need Atomic
Ops and we can't tell whether the Root Complex would support them
(Gerd Bayer)
- Leave Precision Time Measurement disabled until a driver enables it
to avoid PCIe errors (Mika Westerberg)
- Make pci_set_vga_state() fail if bridge doesn't support VGA
routing, i.e., PCI_BRIDGE_CTL_VGA is not writable, and return
errors to vga_get() callers including userspace via
/dev/vga_arbiter (Simon Richter)
- Validate max-link-speed from DT in j721e, brcmstb, mediatek-gen3,
rzg3s drivers (where the actual controller constraints are known),
and remove validation from the generic OF DT accessor (Hans Zhang)
- Remove pc110pad driver (no longer useful after 486 CPU support
removed) and no_pci_devices() (pc110pad was the last user) (Dmitry
Torokhov, Heiner Kallweit)
Resource management:
- Prevent assigning space to unimplemented bridge windows; previously
we mistakenly assumed prefetchable window existed and assigned
space and put a BAR there (Ahmed Naseef)
- Avoid shrinking bridge windows to fit in the initial Root Port
window; fixes one problem with devices with large BARs connected
via switches, e.g., Thunderbolt (Ilpo Järvinen)
- Pass full extent of empty space, not just the aligned space, to
resource_alignf callback so free space before the requested
alignment can be used (Ilpo Järvinen)
- Place small resources before larger ones for better utilization of
address space (Ilpo Järvinen)
- Fix alignment calculation for resource size larger than align,
e.g., bridge windows larger than the 1MB required alignment (Ilpo
Järvinen)
Reset:
- Update slot handling so all ARI functions are treated as being in
the same slot. They're all reset by Secondary Bus Reset, but
previously drivers of ARI functions that appeared to be on a
non-zero device weren't notified and fatal hardware errors could
result (Keith Busch)
- Make sysfs reset_subordinate hotplug safe to avoid spurious hotplug
events (Keith Busch)
- Hide Secondary Bus Reset ('bus') from sysfs reset_methods if masked
by CXL because it has no effect (Vidya Sagar)
- Avoid FLR for AMD NPU device, where it causes the device to hang
(Lizhi Hou)
Error handling:
- Clear only error bits in PCIe Device Status to avoid accidentally
clearing Emergency Power Reduction Detected (Shuai Xue)
- Check for AER errors even in devices without drivers (Lukas Wunner)
- Initialize ratelimit info so DPC and EDR paths log AER error
information (Kuppuswamy Sathyanarayanan)
Power control:
- Add UPD720201/UPD720202 USB 3.0 xHCI Host Controller .compatible so
generic pwrctrl driver can control it (Neil Armstrong)
Hotplug:
- Set LED_HW_PLUGGABLE for NPEM hotplug-capable ports so LED core
doesn't complain when setting brightness fails because the endpoint
is gone (Richard Cheng)
Peer-to-peer DMA:
- Allow wildcards in list of host bridges that support peer-to-peer
DMA between hierarchy domains and add all Google SoCs (Jacob
Moroni)
Endpoint framework:
- Advertise dynamic inbound mapping support in pci-epf-test and
update host pci_endpoint_test to skip doorbell testing if not
advertised by endpoint (Koichiro Den)
- Return 0, not remaining timeout, when MHI eDMA ops complete so
mhi_ep_ring_add_element() doesn't interpret non-zero as failure
(Daniel Hodges)
- Remove vntb and ntb duplicate resource teardown that leads to oops
when .allow_link() fails or .drop_link() is called (Koichiro Den)
- Disable vntb delayed work before clearing BAR mappings and
doorbells to avoid oops caused by doing the work after resources
have been torn down (Koichiro Den)
- Add a way to describe reserved subregions within BARs, e.g.,
platform-owned fixed register windows, and use it for the RK3588
BAR4 DMA ctrl window (Koichiro Den)
- Add BAR_DISABLED for BARs that will never be available to an EPF
driver, and change some BAR_RESERVED annotations to BAR_DISABLED
(Niklas Cassel)
- Add NTB .get_dma_dev() callback for cases where DMA API requires a
different device, e.g., vNTB devices (Koichiro Den)
- Add reserved region types for MSI-X Table and PBA so Endpoint
controllers can them as describe hardware-owned regions in a
BAR_RESERVED BAR (Manikanta Maddireddy)
- Make Tegra194/234 BAR0 programmable and remove 1MB size limit
(Manikanta Maddireddy)
- Expose Tegra BAR2 (MSI-X) and BAR4 (DMA) as 64-bit BAR_RESERVED
(Manikanta Maddireddy)
- Add Tegra194 and Tegra234 device table entries to pci_endpoint_test
(Manikanta Maddireddy)
- Skip the BAR subrange selftest if there are not enough inbound
window resources to run the test (Christian Bruel)
New native PCIe controller drivers:
- Add DT binding and driver for Andes QiLai SoC PCIe host controller
(Randolph Lin)
- Add DT binding and driver for ESWIN PCIe Root Complex (Senchuan
Zhang)
Baikal T-1 PCIe controller driver:
- Remove driver since it never quite became usable (Andy Shevchenko)
Cadence PCIe controller driver:
- Implement byte/word config reads with dword (32-bit) reads because
some Cadence controllers don't support sub-dword accesses (Aksh
Garg)
CIX Sky1 PCIe controller driver:
- Add 'power-domains' to DT binding for SCMI power domain (Gary Yang)
Freescale i.MX6 PCIe controller driver:
- Add i.MX94 and i.MX943 to fsl,imx6q-pcie-ep DT binding (Richard
Zhu)
- Delay instead of polling for L2/L3 Ready after PME_Turn_off when
suspending i.MX6SX because LTSSM registers are inaccessible
(Richard Zhu)
- Separate PERST# assertion (for resetting endpoints) from core reset
(for resetting the RC itself) to prepare for new DTs with PERST#
GPIO in per-Root Port nodes (Sherry Sun)
- Retain Root Port MSI capability on i.MX7D, i.MX8MM, and i.MX8MQ so
MSI from downstream devices will work (Richard Zhu)
- Fix i.MX95 reference clock source selection when internal refclk is
used (Franz Schnyder)
Freescale Layerscape PCIe controller driver:
- Allow building as a removable module (Sascha Hauer)
MediaTek PCIe Gen3 controller driver:
- Use dev_err_probe() to simplify error paths and make deferred probe
messages visible in /sys/kernel/debug/devices_deferred (Chen-Yu
Tsai)
- Power off device if setup fails (Chen-Yu Tsai)
- Integrate new pwrctrl API to enable power control for WiFi/BT
adapters on mainboard or in PCIe or M.2 slots (Chen-Yu Tsai)
NVIDIA Tegra194 PCIe controller driver:
- Poll less aggressively and non-atomically for PME_TO_Ack during
transition to L2 (Vidya Sagar)
- Disable LTSSM after transition to Detect on surprise link down to
stop toggling between Polling and Detect (Manikanta Maddireddy)
- Don't force the device into the D0 state before L2 when suspending
or shutting down the controller (Vidya Sagar)
- Disable PERST# IRQ only in Endpoint mode because it's not
registered in Root Port mode (Manikanta Maddireddy)
- Handle 'nvidia,refclk-select' as optional (Vidya Sagar)
- Disable direct speed change in Endpoint mode so link speed change
is controlled by the host (Vidya Sagar)
- Set LTR values before link up to avoid bogus LTR messages with 0
latency (Vidya Sagar)
- Allow system suspend when the Endpoint link is down (Vidya Sagar)
- Use DWC IP core version, not Tegra custom values, to avoid DWC core
version check warnings (Manikanta Maddireddy)
- Apply ECRC workaround to devices based on DesignWare 5.00a as well
as 4.90a (Manikanta Maddireddy)
- Disable PM Substate L1.2 in Endpoint mode to work around Tegra234
erratum (Vidya Sagar)
- Delay post-PERST# cleanup until core is powered on to avoid CBB
timeout (Manikanta Maddireddy)
- Assert CLKREQ# so switches that forward it to their downstream side
can bring up those links successfully (Vidya Sagar)
- Calibrate pipe to UPHY for Endpoint mode to reset stale PLL state
from any previous bad link state (Vidya Sagar)
- Remove IRQF_ONESHOT flag from Endpoint interrupt registration so
DMA driver and Endpoint controller driver can share the interrupt
line (Vidya Sagar)
- Enable DMA interrupt to support DMA in both Root Port and Endpoint
modes (Vidya Sagar)
- Enable hardware link retraining after link goes down in Endpoint
mode (Vidya Sagar)
- Add DT binding and driver support for core clock monitoring (Vidya
Sagar)
Qualcomm PCIe controller driver:
- Advertise 'Hot-Plug Capable' and set 'No Command Completed Support'
since Qcom Root Ports support hotplug events like DL_Up/Down and
can accept writes to Slot Control without delays between writes
(Krishna Chaitanya Chundru)
Renesas R-Car PCIe controller driver:
- Mark Endpoint BAR0 and BAR2 as Resizable (Koichiro Den)
- Reduce EPC BAR alignment requirement to 4K (Koichiro Den)
Renesas RZ/G3S PCIe controller driver:
- Add RZ/G3E to DT binding and to driver (John Madieu)
- Assert (not deassert) resets in probe error path (John Madieu)
- Assert resets in suspend path in reverse order they were deasserted
during probe (John Madieu)
- Rework inbound window algorithm to prevent mapping more than
intended region and enforce alignment on size, to prepare for
RZ/G3E support (John Madieu)
Rockchip DesignWare PCIe controller driver:
- Add tracepoints for PCIe controller LTSSM transitions and link rate
changes (Shawn Lin)
- Trace LTSSM events collected by the dw-rockchip debug FIFO (Shawn
Lin)
SOPHGO PCIe controller driver:
- Disable ASPM L0s and L1 on Sophgo 2042 PCIe Root Ports that
advertise support for them (Yao Zi)
Synopsys DesignWare PCIe controller driver:
- Continue with system suspend even if an Endpoint doesn't respond
with PME_TO_Ack message (Manivannan Sadhasivam)
- Set Endpoint MSI-X Table Size in the correct function of a
multi-function device when configuring MSI-X, not in Function 0
(Aksh Garg)
- Set Max Link Width and Max Link Speed for all functions of a
multi-function device, not just Function 0 (Aksh Garg)
- Expose PCIe event counters in groups 5-7 in debugfs (Hans Zhang)
Miscellaneous:
- Warn only once about invalid ACS kernel parameter format (Richard
Cheng)
- Suppress FW_BUG warning when writing sysfs 'numa_node' with the
current value (Li RongQing)
- Drop redundant 'depends on PCI' from Kconfig (Julian Braha)"
* tag 'pci-v7.1-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/pci/pci: (165 commits)
PCI/P2PDMA: Add Google SoCs to the P2P DMA host bridge list
PCI/P2PDMA: Allow wildcard Device IDs in host bridge list
PCI: sg2042: Avoid L0s and L1 on Sophgo 2042 PCIe Root Ports
PCI: cadence: Add flags for disabling ASPM capability for broken Root Ports
PCI: tegra194: Add core monitor clock support
dt-bindings: PCI: tegra194: Add monitor clock support
PCI: tegra194: Enable hardware hot reset mode in Endpoint mode
PCI: tegra194: Enable DMA interrupt
PCI: tegra194: Remove IRQF_ONESHOT flag during Endpoint interrupt registration
PCI: tegra194: Calibrate pipe to UPHY for Endpoint mode
PCI: tegra194: Assert CLKREQ# explicitly by default
PCI: tegra194: Fix CBB timeout caused by DBI access before core power-on
PCI: tegra194: Disable L1.2 capability of Tegra234 EP
PCI: dwc: Apply ECRC workaround to DesignWare 5.00a as well
PCI: tegra194: Use DWC IP core version
PCI: tegra194: Free up Endpoint resources during remove()
PCI: tegra194: Allow system suspend when the Endpoint link is not up
PCI: tegra194: Set LTR message request before PCIe link up in Endpoint mode
PCI: tegra194: Disable direct speed change for Endpoint mode
PCI: tegra194: Use devm_gpiod_get_optional() to parse "nvidia,refclk-select"
...
Everything:
Total patches: 368
Reviews/patch: 1.56
Reviewed rate: 74%
Excluding DAMON:
Total patches: 316
Reviews/patch: 1.77
Reviewed rate: 81%
Excluding DAMON and zram:
Total patches: 306
Reviews/patch: 1.81
Reviewed rate: 82%
Excluding DAMON, zram and maple_tree:
Total patches: 276
Reviews/patch: 2.01
Reviewed rate: 91%
Significant patch series in this merge:
- The 30 patch series "maple_tree: Replace big node with maple copy"
from Liam Howlett is mainly prepararatory work for ongoing development
but it does reduce stack usage and is an improvement.
- The 12 patch series "mm, swap: swap table phase III: remove swap_map"
from Kairui Song offers memory savings by removing the static swap_map.
It also yields some CPU savings and implements several cleanups.
- The 2 patch series "mm: memfd_luo: preserve file seals" from Pratyush
Yadav adds file seal preservation to LUO's memfd code.
- The 2 patch series "mm: zswap: add per-memcg stat for incompressible
pages" from Jiayuan Chen adds additional userspace stats reportng to
zswap.
- The 4 patch series "arch, mm: consolidate empty_zero_page" from Mike
Rapoport implements some cleanups for our handling of ZERO_PAGE() and
zero_pfn.
- The 2 patch series "mm/kmemleak: Improve scan_should_stop()
implementation" from Zhongqiu Han provides an robustness improvement and
some cleanups in the kmemleak code.
- The 4 patch series "Improve khugepaged scan logic" from Vernon Yang
"improves the khugepaged scan logic and reduces CPU consumption by
prioritizing scanning tasks that access memory frequently".
- The 2 patch series "Make KHO Stateless" from Jason Miu simplifies
Kexec Handover by "transitioning KHO from an xarray-based metadata
tracking system with serialization to a radix tree data structure that
can be passed directly to the next kernel"
- The 3 patch series "mm: vmscan: add PID and cgroup ID to vmscan
tracepoints" from Thomas Ballasi and Steven Rostedt enhances vmscan's
tracepointing.
- The 5 patch series "mm: arch/shstk: Common shadow stack mapping helper
and VM_NOHUGEPAGE" from Catalin Marinas is a cleanup for the shadow
stack code: remove per-arch code in favour of a generic implementation.
- The 2 patch series "Fix KASAN support for KHO restored vmalloc
regions" from Pasha Tatashin fixes a WARN() which can be emitted the KHO
restores a vmalloc area.
- The 4 patch series "mm: Remove stray references to pagevec" from Tal
Zussman provides several cleanups, mainly udpating references to "struct
pagevec", which became folio_batch three years ago.
- The 17 patch series "mm: Eliminate fake head pages from vmemmap
optimization" from Kiryl Shutsemau simplifies the HugeTLB vmemmap
optimization (HVO) by changing how tail pages encode their relationship
to the head page.
- The 2 patch series "mm/damon/core: improve DAMOS quota efficiency for
core layer filters" from SeongJae Park improves two problematic
behaviors of DAMOS that makes it less efficient when core layer filters
are used.
- The 3 patch series "mm/damon: strictly respect min_nr_regions" from
SeongJae Park improves DAMON usability by extending the treatment of the
min_nr_regions user-settable parameter.
- The 3 patch series "mm/page_alloc: pcp locking cleanup" from Vlastimil
Babka is a proper fix for a previously hotfixed SMP=n issue. Code
simplifications and cleanups ennsed.
- The 16 patch series "mm: cleanups around unmapping / zapping" from
David Hildenbrand implements "a bunch of cleanups around unmapping and
zapping. Mostly simplifications, code movements, documentation and
renaming of zapping functions".
- The 6 patch series "support batched checking of the young flag for
MGLRU" from Baolin Wang supports batched checking of the young flag for
MGLRU. It's part cleanups; one benchmark shows large performance
benefits for arm64.
- The 5 patch series "memcg: obj stock and slab stat caching cleanups"
from Johannes Weiner provides memcg cleanup and robustness improvements.
- The 5 patch series "Allow order zero pages in page reporting" from
Yuvraj Sakshith enhances page_reporting's free page reporting - it is
presently and undesirably order-0 pages when reporting free memory.
- The 6 patch series "mm: vma flag tweaks" from Lorenzo Stoakes is
cleanup work following from the recent conversion of the VMA flags to a
bitmap.
- The 10 patch series "mm/damon: add optional debugging-purpose sanity
checks" from SeongJae Park adds some more developer-facing debug checks
into DAMON core.
- The 2 patch series "mm/damon: test and document power-of-2
min_region_sz requirement" from SeongJae Park adds an additional DAMON
kunit test and makes some adjustments to the addr_unit parameter
handling.
- The 3 patch series "mm/damon/core: make passed_sample_intervals
comparisons overflow-safe" from SeongJae Park fixes a hard-to-hit time
overflow issue in DAMON core.
- The 7 patch series "mm/damon: improve/fixup/update ratio calculation,
test and documentation" from SeongJae Park is a "batch of misc/minor
improvements and fixups" for DAMON.
- The 4 patch series "mm: move vma_(kernel|mmu)_pagesize() out of
hugetlb.c" from David Hildenbrand fixes a possible issue with dax-device
when CONFIG_HUGETLB=n. Some code movement was required.
- The 6 patch series "zram: recompression cleanups and tweaks" from
Sergey Senozhatsky provides "a somewhat random mix of fixups,
recompression cleanups and improvements" in the zram code.
- The 11 patch series "mm/damon: support multiple goal-based quota
tuning algorithms" from SeongJae Park extend DAMOS quotas goal
auto-tuning to support multiple tuning algorithms that users can select.
- The 4 patch series "mm: thp: reduce unnecessary
start_stop_khugepaged()" from Breno Leitao fixes the khugpaged sysfs
handling so we no longer spam the logs with reams of junk when
starting/stopping khugepaged.
- The 3 patch series "mm: improve map count checks" from Lorenzo Stoakes
provides some cleanups and slight fixes in the mremap, mmap and vma
code.
- The 5 patch series "mm/damon: support addr_unit on default monitoring
targets for modules" from SeongJae Park extends the use of DAMON core's
addr_unit tunable.
- The 5 patch series "mm: khugepaged cleanups and mTHP prerequisites"
from Nico Pache provides cleanups in the khugepaged and is a base for
Nico's planned khugepaged mTHP support.
- The 15 patch series "mm: memory hot(un)plug and SPARSEMEM cleanups"
from David Hildenbrand implements code movement and cleanups in the
memhotplug and sparsemem code.
- The 2 patch series "mm: remove CONFIG_ARCH_ENABLE_MEMORY_HOTREMOVE and
cleanup CONFIG_MIGRATION" from David Hildenbrand rationalizes some
memhotplug Kconfig support.
- The 6 patch series "change young flag check functions to return bool"
from Baolin Wang is "a cleanup patchset to change all young flag check
functions to return bool".
- The 3 patch series "mm/damon/sysfs: fix memory leak and NULL
dereference issues" from Josh Law and SeongJae Park fixes a few
potential DAMON bugs.
- The 25 patch series "mm/vma: convert vm_flags_t to vma_flags_t in vma
code" from "converts a lot of the existing use of the legacy vm_flags_t
data type to the new vma_flags_t type which replaces it". Mainly in the
vma code.
- The 21 patch series "mm: expand mmap_prepare functionality and usage"
from Lorenzo Stoakes "expands the mmap_prepare functionality, which is
intended to replace the deprecated f_op->mmap hook which has been the
source of bugs and security issues for some time". Cleanups,
documentation, extension of mmap_prepare into filesystem drivers.
- The 13 patch series "mm/huge_memory: refactor zap_huge_pmd()" from
Lorenzo Stoakes simplifies and cleans up zap_huge_pmd(). Additional
cleanups around vm_normal_folio_pmd() and the softleaf functionality are
performed.
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Merge tag 'mm-stable-2026-04-13-21-45' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Pull MM updates from Andrew Morton:
- "maple_tree: Replace big node with maple copy" (Liam Howlett)
Mainly prepararatory work for ongoing development but it does reduce
stack usage and is an improvement.
- "mm, swap: swap table phase III: remove swap_map" (Kairui Song)
Offers memory savings by removing the static swap_map. It also yields
some CPU savings and implements several cleanups.
- "mm: memfd_luo: preserve file seals" (Pratyush Yadav)
File seal preservation to LUO's memfd code
- "mm: zswap: add per-memcg stat for incompressible pages" (Jiayuan
Chen)
Additional userspace stats reportng to zswap
- "arch, mm: consolidate empty_zero_page" (Mike Rapoport)
Some cleanups for our handling of ZERO_PAGE() and zero_pfn
- "mm/kmemleak: Improve scan_should_stop() implementation" (Zhongqiu
Han)
A robustness improvement and some cleanups in the kmemleak code
- "Improve khugepaged scan logic" (Vernon Yang)
Improve khugepaged scan logic and reduce CPU consumption by
prioritizing scanning tasks that access memory frequently
- "Make KHO Stateless" (Jason Miu)
Simplify Kexec Handover by transitioning KHO from an xarray-based
metadata tracking system with serialization to a radix tree data
structure that can be passed directly to the next kernel
- "mm: vmscan: add PID and cgroup ID to vmscan tracepoints" (Thomas
Ballasi and Steven Rostedt)
Enhance vmscan's tracepointing
- "mm: arch/shstk: Common shadow stack mapping helper and
VM_NOHUGEPAGE" (Catalin Marinas)
Cleanup for the shadow stack code: remove per-arch code in favour of
a generic implementation
- "Fix KASAN support for KHO restored vmalloc regions" (Pasha Tatashin)
Fix a WARN() which can be emitted the KHO restores a vmalloc area
- "mm: Remove stray references to pagevec" (Tal Zussman)
Several cleanups, mainly udpating references to "struct pagevec",
which became folio_batch three years ago
- "mm: Eliminate fake head pages from vmemmap optimization" (Kiryl
Shutsemau)
Simplify the HugeTLB vmemmap optimization (HVO) by changing how tail
pages encode their relationship to the head page
- "mm/damon/core: improve DAMOS quota efficiency for core layer
filters" (SeongJae Park)
Improve two problematic behaviors of DAMOS that makes it less
efficient when core layer filters are used
- "mm/damon: strictly respect min_nr_regions" (SeongJae Park)
Improve DAMON usability by extending the treatment of the
min_nr_regions user-settable parameter
- "mm/page_alloc: pcp locking cleanup" (Vlastimil Babka)
The proper fix for a previously hotfixed SMP=n issue. Code
simplifications and cleanups ensued
- "mm: cleanups around unmapping / zapping" (David Hildenbrand)
A bunch of cleanups around unmapping and zapping. Mostly
simplifications, code movements, documentation and renaming of
zapping functions
- "support batched checking of the young flag for MGLRU" (Baolin Wang)
Batched checking of the young flag for MGLRU. It's part cleanups; one
benchmark shows large performance benefits for arm64
- "memcg: obj stock and slab stat caching cleanups" (Johannes Weiner)
memcg cleanup and robustness improvements
- "Allow order zero pages in page reporting" (Yuvraj Sakshith)
Enhance free page reporting - it is presently and undesirably order-0
pages when reporting free memory.
- "mm: vma flag tweaks" (Lorenzo Stoakes)
Cleanup work following from the recent conversion of the VMA flags to
a bitmap
- "mm/damon: add optional debugging-purpose sanity checks" (SeongJae
Park)
Add some more developer-facing debug checks into DAMON core
- "mm/damon: test and document power-of-2 min_region_sz requirement"
(SeongJae Park)
An additional DAMON kunit test and makes some adjustments to the
addr_unit parameter handling
- "mm/damon/core: make passed_sample_intervals comparisons
overflow-safe" (SeongJae Park)
Fix a hard-to-hit time overflow issue in DAMON core
- "mm/damon: improve/fixup/update ratio calculation, test and
documentation" (SeongJae Park)
A batch of misc/minor improvements and fixups for DAMON
- "mm: move vma_(kernel|mmu)_pagesize() out of hugetlb.c" (David
Hildenbrand)
Fix a possible issue with dax-device when CONFIG_HUGETLB=n. Some code
movement was required.
- "zram: recompression cleanups and tweaks" (Sergey Senozhatsky)
A somewhat random mix of fixups, recompression cleanups and
improvements in the zram code
- "mm/damon: support multiple goal-based quota tuning algorithms"
(SeongJae Park)
Extend DAMOS quotas goal auto-tuning to support multiple tuning
algorithms that users can select
- "mm: thp: reduce unnecessary start_stop_khugepaged()" (Breno Leitao)
Fix the khugpaged sysfs handling so we no longer spam the logs with
reams of junk when starting/stopping khugepaged
- "mm: improve map count checks" (Lorenzo Stoakes)
Provide some cleanups and slight fixes in the mremap, mmap and vma
code
- "mm/damon: support addr_unit on default monitoring targets for
modules" (SeongJae Park)
Extend the use of DAMON core's addr_unit tunable
- "mm: khugepaged cleanups and mTHP prerequisites" (Nico Pache)
Cleanups to khugepaged and is a base for Nico's planned khugepaged
mTHP support
- "mm: memory hot(un)plug and SPARSEMEM cleanups" (David Hildenbrand)
Code movement and cleanups in the memhotplug and sparsemem code
- "mm: remove CONFIG_ARCH_ENABLE_MEMORY_HOTREMOVE and cleanup
CONFIG_MIGRATION" (David Hildenbrand)
Rationalize some memhotplug Kconfig support
- "change young flag check functions to return bool" (Baolin Wang)
Cleanups to change all young flag check functions to return bool
- "mm/damon/sysfs: fix memory leak and NULL dereference issues" (Josh
Law and SeongJae Park)
Fix a few potential DAMON bugs
- "mm/vma: convert vm_flags_t to vma_flags_t in vma code" (Lorenzo
Stoakes)
Convert a lot of the existing use of the legacy vm_flags_t data type
to the new vma_flags_t type which replaces it. Mainly in the vma
code.
- "mm: expand mmap_prepare functionality and usage" (Lorenzo Stoakes)
Expand the mmap_prepare functionality, which is intended to replace
the deprecated f_op->mmap hook which has been the source of bugs and
security issues for some time. Cleanups, documentation, extension of
mmap_prepare into filesystem drivers
- "mm/huge_memory: refactor zap_huge_pmd()" (Lorenzo Stoakes)
Simplify and clean up zap_huge_pmd(). Additional cleanups around
vm_normal_folio_pmd() and the softleaf functionality are performed.
* tag 'mm-stable-2026-04-13-21-45' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (369 commits)
mm: fix deferred split queue races during migration
mm/khugepaged: fix issue with tracking lock
mm/huge_memory: add and use has_deposited_pgtable()
mm/huge_memory: add and use normal_or_softleaf_folio_pmd()
mm: add softleaf_is_valid_pmd_entry(), pmd_to_softleaf_folio()
mm/huge_memory: separate out the folio part of zap_huge_pmd()
mm/huge_memory: use mm instead of tlb->mm
mm/huge_memory: remove unnecessary sanity checks
mm/huge_memory: deduplicate zap deposited table call
mm/huge_memory: remove unnecessary VM_BUG_ON_PAGE()
mm/huge_memory: add a common exit path to zap_huge_pmd()
mm/huge_memory: handle buggy PMD entry in zap_huge_pmd()
mm/huge_memory: have zap_huge_pmd return a boolean, add kdoc
mm/huge: avoid big else branch in zap_huge_pmd()
mm/huge_memory: simplify vma_is_specal_huge()
mm: on remap assert that input range within the proposed VMA
mm: add mmap_action_map_kernel_pages[_full]()
uio: replace deprecated mmap hook with mmap_prepare in uio_info
drivers: hv: vmbus: replace deprecated mmap hook with mmap_prepare
mm: allow handling of stacked mmap_prepare hooks in more drivers
...
arena_vm_open() only bumps vml->mmap_count but never registers the
child VMA in arena->vma_list. The vml->vma always points at the
parent VMA, so after parent munmap the pointer dangles. If the child
then calls bpf_arena_free_pages(), zap_pages() reads the stale
vml->vma triggering use-after-free.
Fix this by preventing the arena VMA from being inherited across
fork with VM_DONTCOPY, and preventing VMA splits via the may_split
callback.
Also reject mremap with a .mremap callback returning -EINVAL. A
same-size mremap(MREMAP_FIXED) on the full arena VMA reaches
copy_vma() through the following path:
check_prep_vma() - returns 0 early: new_len == old_len
skips VM_DONTEXPAND check
prep_move_vma() - vm_start == old_addr and
vm_end == old_addr + old_len
so may_split is never called
move_vma()
copy_vma_and_data()
copy_vma()
vm_area_dup() - copies vm_private_data (vml pointer)
vm_ops->open() - bumps vml->mmap_count
vm_ops->mremap() - returns -EINVAL, rollback unmaps new VMA
The refcount ensures the rollback's arena_vm_close does not free
the vml shared with the original VMA.
Reported-by: Weiming Shi <bestswngs@gmail.com>
Reported-by: Xiang Mei <xmei5@asu.edu>
Fixes: 317460317a ("bpf: Introduce bpf_arena.")
Reviewed-by: Emil Tsalapatis <emil@etsalapatis.com>
Link: https://lore.kernel.org/r/20260413194245.21449-1-alexei.starovoitov@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
- Cgroup sub-scheduler groundwork. Multiple BPF schedulers can be
attached to cgroups and the dispatch path is made hierarchical. This
involves substantial restructuring of the core dispatch, bypass,
watchdog, and dump paths to be per-scheduler, along with new
infrastructure for scheduler ownership enforcement, lifecycle
management, and cgroup subtree iteration. The enqueue path is not yet
updated and will follow in a later cycle.
- scx_bpf_dsq_reenq() generalized to support any DSQ including remote
local DSQs and user DSQs. Built on top of this, SCX_ENQ_IMMED
guarantees that tasks dispatched to local DSQs either run immediately
or get reenqueued back through ops.enqueue(), giving schedulers tighter
control over queueing latency. Also useful for opportunistic CPU
sharing across sub-schedulers.
- ops.dequeue() was only invoked when the core knew a task was in BPF
data structures, missing scheduling property change events and skipping
callbacks for non-local DSQ dispatches from ops.select_cpu(). Fixed to
guarantee exactly one ops.dequeue() call when a task leaves BPF
scheduler custody.
- Kfunc access validation moved from runtime to BPF verifier time,
removing runtime mask enforcement.
- Idle SMT sibling prioritization in the idle CPU selection path.
- Documentation, selftest, and tooling updates. Misc bug fixes and
cleanups.
- Merges from tip/sched-core, cgroup/for-7.1, and for-7.0-fixes to
resolve dependencies and conflicts for the above changes.
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Merge tag 'sched_ext-for-7.1' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/sched_ext
Pull sched_ext updates from Tejun Heo:
- cgroup sub-scheduler groundwork
Multiple BPF schedulers can be attached to cgroups and the dispatch
path is made hierarchical. This involves substantial restructuring of
the core dispatch, bypass, watchdog, and dump paths to be
per-scheduler, along with new infrastructure for scheduler ownership
enforcement, lifecycle management, and cgroup subtree iteration
The enqueue path is not yet updated and will follow in a later cycle
- scx_bpf_dsq_reenq() generalized to support any DSQ including remote
local DSQs and user DSQs
Built on top of this, SCX_ENQ_IMMED guarantees that tasks dispatched
to local DSQs either run immediately or get reenqueued back through
ops.enqueue(), giving schedulers tighter control over queueing
latency
Also useful for opportunistic CPU sharing across sub-schedulers
- ops.dequeue() was only invoked when the core knew a task was in BPF
data structures, missing scheduling property change events and
skipping callbacks for non-local DSQ dispatches from ops.select_cpu()
Fixed to guarantee exactly one ops.dequeue() call when a task leaves
BPF scheduler custody
- Kfunc access validation moved from runtime to BPF verifier time,
removing runtime mask enforcement
- Idle SMT sibling prioritization in the idle CPU selection path
- Documentation, selftest, and tooling updates. Misc bug fixes and
cleanups
* tag 'sched_ext-for-7.1' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/sched_ext: (134 commits)
tools/sched_ext: Add explicit cast from void* in RESIZE_ARRAY()
sched_ext: Make string params of __ENUM_set() const
tools/sched_ext: Kick home CPU for stranded tasks in scx_qmap
sched_ext: Drop spurious warning on kick during scheduler disable
sched_ext: Warn on task-based SCX op recursion
sched_ext: Rename scx_kf_allowed_on_arg_tasks() to scx_kf_arg_task_ok()
sched_ext: Remove runtime kfunc mask enforcement
sched_ext: Add verifier-time kfunc context filter
sched_ext: Drop redundant rq-locked check from scx_bpf_task_cgroup()
sched_ext: Decouple kfunc unlocked-context check from kf_mask
sched_ext: Fix ops.cgroup_move() invocation kf_mask and rq tracking
sched_ext: Track @p's rq lock across set_cpus_allowed_scx -> ops.set_cpumask
sched_ext: Add select_cpu kfuncs to scx_kfunc_ids_unlocked
sched_ext: Drop TRACING access to select_cpu kfuncs
selftests/sched_ext: Fix wrong DSQ ID in peek_dsq error message
sched_ext: Documentation: improve accuracy of task lifecycle pseudo-code
selftests/sched_ext: Improve runner error reporting for invalid arguments
sched_ext: Documentation: Fix scx_bpf_move_to_local kfunc name
sched_ext: Documentation: Add ops.dequeue() to task lifecycle
tools/sched_ext: Fix off-by-one in scx_sdt payload zeroing
...
- New default WQ_AFFN_CACHE_SHARD affinity scope subdivides LLCs into
smaller shards to improve scalability on machines with many CPUs per
LLC.
- Misc: system_dfl_long_wq for long unbound works, devm_alloc_workqueue()
for device-managed allocation, sysfs exposure for ordered workqueues and
the EFI workqueue, removal of HK_TYPE_WQ from wq_unbound_cpumask, and
various small fixes.
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Merge tag 'wq-for-7.1' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq
Pull workqueue updates from Tejun Heo:
- New default WQ_AFFN_CACHE_SHARD affinity scope subdivides LLCs into
smaller shards to improve scalability on machines with many CPUs per
LLC
- Misc:
- system_dfl_long_wq for long unbound works
- devm_alloc_workqueue() for device-managed allocation
- sysfs exposure for ordered workqueues and the EFI workqueue
- removal of HK_TYPE_WQ from wq_unbound_cpumask
- various small fixes
* tag 'wq-for-7.1' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq: (21 commits)
workqueue: validate cpumask_first() result in llc_populate_cpu_shard_id()
workqueue: use NR_STD_WORKER_POOLS instead of hardcoded value
workqueue: avoid unguarded 64-bit division
docs: workqueue: document WQ_AFFN_CACHE_SHARD affinity scope
workqueue: add test_workqueue benchmark module
tools/workqueue: add CACHE_SHARD support to wq_dump.py
workqueue: set WQ_AFFN_CACHE_SHARD as the default affinity scope
workqueue: add WQ_AFFN_CACHE_SHARD affinity scope
workqueue: fix typo in WQ_AFFN_SMT comment
workqueue: Remove HK_TYPE_WQ from affecting wq_unbound_cpumask
workqueue: unlink pwqs from wq->pwqs list in alloc_and_link_pwqs() error path
workqueue: Remove NULL wq WARN in __queue_delayed_work()
workqueue: fix parse_affn_scope() prefix matching bug
workqueue: devres: Add device-managed allocate workqueue
workqueue: Add system_dfl_long_wq for long unbound works
tools/workqueue/wq_dump.py: add NODE prefix to all node columns
tools/workqueue/wq_dump.py: fix column alignment in node_nr/max_active section
tools/workqueue/wq_dump.py: remove backslash separator from node_nr/max_active header
efi: Allow to expose the workqueue via sysfs
workqueue: Allow to expose ordered workqueues via sysfs
...
- cgroup_file_notify() locking converted from a global lock to
per-cgroup_file spinlock with a lockless fast-path when no notification
is needed.
- Misc changes including exposing cgroup helpers for sched_ext and minor
fixes.
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Merge tag 'cgroup-for-7.1' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup
Pull cgroup updates from Tejun Heo:
- cgroup_file_notify() locking converted from a global lock to
per-cgroup_file spinlock with a lockless fast-path when no
notification is needed
- Misc changes including exposing cgroup helpers for sched_ext and
minor fixes
* tag 'cgroup-for-7.1' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
cgroup/rdma: fix swapped arguments in pr_warn() format string
cgroup/dmem: remove region parameter from dmemcg_parse_limit
cgroup: replace global cgroup_file_kn_lock with per-cgroup_file lock
cgroup: add lockless fast-path checks to cgroup_file_notify()
cgroup: reduce cgroup_file_kn_lock hold time in cgroup_file_notify()
cgroup: Expose some cgroup helpers
BPF_STX through ARG_IMPRECISE dst should be recognized as a local
spill and join at_stack with the written value. For example,
consider the following situation:
// r1 = ARG_IMPRECISE{mask=BIT(0)|BIT(1)}
*(u64 *)(r1 + 0) = r8
Here the analysis should produce an equivalent of
at_stack[*] = join(old, r8)
BPF_ST through multi-offset or imprecise dst should join at_stack with
none instead of overwriting the slots. For example, consider the
following situation:
// r1 = ARG_IMPRECISE{mask=BIT(0)|BIT(1)}
*(u64 *)(r1 + 0) = 0
Here the analysis should produce an equivalent of
at_stack[*r1] = join(old, none).
Move the definition of the clear_overlapping_stack_slots() in order to
have __arg_track_join() visible. Remove the OFF_IMPRECISE constant to
avoid having two ways to express imprecise offset.
Only 'offset-imprecise {frame=N, cnt=0}' remains.
Fixes: bf0c571f7f ("bpf: introduce forward arg-tracking dataflow analysis")
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20260413-stacklive-fixes-v2-1-398e126e5cf3@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
delay accounting started populating taskstats records with a valid version
field via fill_pid() and fill_tgid().
Later, commit ad4ecbcba7 ("[PATCH] delay accounting taskstats interface
send tgid once") changed the TGID exit path to send the cached
signal->stats aggregate directly instead of building the outgoing record
through fill_tgid(). Unlike fill_tgid(), fill_tgid_exit() only
accumulates accounting data and never initializes stats->version.
As a result, TGID exit notifications can reach userspace with version == 0
even though PID exit notifications and TASKSTATS_CMD_GET replies carry a
valid taskstats version.
This is easy to reproduce with `tools/accounting/getdelays.c`.
I have a small follow-up patch for that tool which:
1. increases the receive buffer/message size so the pid+tgid
combined exit notification is not dropped/truncated
2. prints `stats->version`.
With that patch, the reproducer is:
Terminal 1:
./getdelays -d -v -l -m 0
Terminal 2:
taskset -c 0 python3 -c 'import threading,time; t=threading.Thread(target=time.sleep,args=(0.1,)); t.start(); t.join()'
That produces both PID and TGID exit notifications for the same
process. The PID exit record reports a valid taskstats version, while
the TGID exit record reports `version 0`.
This patch (of 2):
Set stats->version = TASKSTATS_VERSION after copying the cached TGID
aggregate into the outgoing netlink payload so all taskstats records are
self-describing again.
Link: https://lkml.kernel.org/r/ba83d934e59edd431b693607de573eb9ca059309.1774810498.git.cyyzero16@gmail.com
Fixes: ad4ecbcba7 ("[PATCH] delay accounting taskstats interface send tgid once")
Signed-off-by: Yiyang Chen <cyyzero16@gmail.com>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: Dr. Thomas Orgis <thomas.orgis@uni-hamburg.de>
Cc: Fan Yu <fan.yu9@zte.com.cn>
Cc: Wang Yaxin <wang.yaxin@zte.com.cn>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Please consider pulling these changes from the signed kernel-7.1-rc1.misc tag.
Thanks!
Christian
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Merge tag 'kernel-7.1-rc1.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs
Pull pid_namespace updates from Christian Brauner:
- pid_namespace: make init creation more flexible
Annotate ->child_reaper accesses with {READ,WRITE}_ONCE() to protect
the unlocked readers from cpu/compiler reordering, and enforce that
pid 1 in a pid namespace is always the first allocated pid (the
set_tid path already required this).
On top of that, allow opening pid_for_children before the pid
namespace init has been created. This lets one process create the pid
namespace and a different process create the init via setns(), which
makes clone3(set_tid) usable in all cases evenly and is particularly
useful to CRIU when restoring nested containers.
A new selftest covers both the basic create-pidns-then-init flow and
the cross-process variant, and a MAINTAINERS entry for the pid
namespace code is added.
- unrelated signal cleanup: update outdated comment for the removed
freezable_schedule()
* tag 'kernel-7.1-rc1.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
signal: update outdated comment for removed freezable_schedule()
MAINTAINERS: add a pid namespace entry
selftests: Add tests for creating pidns init via setns
pid_namespace: allow opening pid_for_children before init was created
pid: check init is created first after idr alloc
pid_namespace: avoid optimization of accesses to ->child_reaper
Please consider pulling these changes from the signed vfs-7.1-rc1.mount.v2 tag.
Thanks!
Christian
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Merge tag 'vfs-7.1-rc1.mount.v2' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs
Pull vfs mount updates from Christian Brauner:
- Add FSMOUNT_NAMESPACE flag to fsmount() that creates a new mount
namespace with the newly created filesystem attached to a copy of the
real rootfs. This returns a namespace file descriptor instead of an
O_PATH mount fd, similar to how OPEN_TREE_NAMESPACE works for
open_tree().
This allows creating a new filesystem and immediately placing it in a
new mount namespace in a single operation, which is useful for
container runtimes and other namespace-based isolation mechanisms.
This accompanies OPEN_TREE_NAMESPACE and avoids a needless detour via
OPEN_TREE_NAMESPACE to get the same effect. Will be especially useful
when you mount an actual filesystem to be used as the container
rootfs.
- Currently, creating a new mount namespace always copies the entire
mount tree from the caller's namespace. For containers and sandboxes
that intend to build their mount table from scratch this is wasteful:
they inherit a potentially large mount tree only to immediately tear
it down.
This series adds support for creating a mount namespace that contains
only a clone of the root mount, with none of the child mounts. Two
new flags are introduced:
- CLONE_EMPTY_MNTNS (0x400000000) for clone3(), using the 64-bit flag space
- UNSHARE_EMPTY_MNTNS (0x00100000) for unshare()
Both flags imply CLONE_NEWNS. The resulting namespace contains a
single nullfs root mount with an immutable empty directory. The
intended workflow is to then mount a real filesystem (e.g., tmpfs)
over the root and build the mount table from there.
- Allow MOVE_MOUNT_BENEATH to target the caller's rootfs, allowing to
switch out the rootfs without pivot_root(2).
The traditional approach to switching the rootfs involves
pivot_root(2) or a chroot_fs_refs()-based mechanism that atomically
updates fs->root for all tasks sharing the same fs_struct. This has
consequences for fork(), unshare(CLONE_FS), and setns().
This series instead decomposes root-switching into individually
atomic, locally-scoped steps:
fd_tree = open_tree(-EBADF, "/newroot", OPEN_TREE_CLONE | OPEN_TREE_CLOEXEC);
fchdir(fd_tree);
move_mount(fd_tree, "", AT_FDCWD, "/", MOVE_MOUNT_BENEATH | MOVE_MOUNT_F_EMPTY_PATH);
chroot(".");
umount2(".", MNT_DETACH);
Since each step only modifies the caller's own state, the
fork/unshare/setns races are eliminated by design.
A key step to making this possible is to remove the locked mount
restriction. Originally MOVE_MOUNT_BENEATH doesn't support mounting
beneath a mount that is locked. The locked mount protects the
underlying mount from being revealed. This is a core mechanism of
unshare(CLONE_NEWUSER | CLONE_NEWNS). The mounts in the new mount
namespace become locked. That effectively makes the new mount table
useless as the caller cannot ever get rid of any of the mounts no
matter how useless they are.
We can lift this restriction though. We simply transfer the locked
property from the top mount to the mount beneath. This works because
what we care about is to protect the underlying mount aka the parent.
The mount mounted between the parent and the top mount takes over the
job of protecting the parent mount from the top mount mount. This
leaves us free to remove the locked property from the top mount which
can consequently be unmounted:
unshare(CLONE_NEWUSER | CLONE_NEWNS)
and we inherit a clone of procfs on /proc then currently we cannot
unmount it as:
umount -l /proc
will fail with EINVAL because the procfs mount is locked.
After this series we can now do:
mount --beneath -t tmpfs tmpfs /proc
umount -l /proc
after which a tmpfs mount has been placed beneath the procfs mount.
The tmpfs mount has become locked and the procfs mount has become
unlocked.
This means you can safely modify an inherited mount table after
unprivileged namespace creation.
Afterwards we simply make it possible to move a mount beneath the
rootfs allowing to upgrade the rootfs.
Removing the locked restriction makes this very useful for containers
created with unshare(CLONE_NEWUSER | CLONE_NEWNS) to reshuffle an
inherited mount table safely and MOVE_MOUNT_BENEATH makes it possible
to switch out the rootfs instead of using the costly pivot_root(2).
* tag 'vfs-7.1-rc1.mount.v2' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
selftests/namespaces: remove unused utils.h include from listns_efault_test
selftests/fsmount_ns: add missing TARGETS and fix cap test
selftests/empty_mntns: fix wrong CLONE_EMPTY_MNTNS hex value in comment
selftests/empty_mntns: fix statmount_alloc() signature mismatch
selftests/statmount: remove duplicate wait_for_pid()
mount: always duplicate mount
selftests/filesystems: add MOVE_MOUNT_BENEATH rootfs tests
move_mount: allow MOVE_MOUNT_BENEATH on the rootfs
move_mount: transfer MNT_LOCKED
selftests/filesystems: add clone3 tests for empty mount namespaces
selftests/filesystems: add tests for empty mount namespaces
namespace: allow creating empty mount namespaces
selftests: add FSMOUNT_NAMESPACE tests
selftests/statmount: add statmount_alloc() helper
tools: update mount.h header
mount: add FSMOUNT_NAMESPACE
mount: simplify __do_loopback()
mount: start iterating from start of rbtree
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Merge tag 'bpf-next-7.1' of git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next
Pull bpf updates from Alexei Starovoitov:
- Welcome new BPF maintainers: Kumar Kartikeya Dwivedi, Eduard
Zingerman while Martin KaFai Lau reduced his load to Reviwer.
- Lots of fixes everywhere from many first time contributors. Thank you
All.
- Diff stat is dominated by mechanical split of verifier.c into
multiple components:
- backtrack.c: backtracking logic and jump history
- states.c: state equivalence
- cfg.c: control flow graph, postorder, strongly connected
components
- liveness.c: register and stack liveness
- fixups.c: post-verification passes: instruction patching, dead
code removal, bpf_loop inlining, finalize fastcall
8k line were moved. verifier.c still stands at 20k lines.
Further refactoring is planned for the next release.
- Replace dynamic stack liveness with static stack liveness based on
data flow analysis.
This improved the verification time by 2x for some programs and
equally reduced memory consumption. New logic is in liveness.c and
supported by constant folding in const_fold.c (Eduard Zingerman,
Alexei Starovoitov)
- Introduce BTF layout to ease addition of new BTF kinds (Alan Maguire)
- Use kmalloc_nolock() universally in BPF local storage (Amery Hung)
- Fix several bugs in linked registers delta tracking (Daniel Borkmann)
- Improve verifier support of arena pointers (Emil Tsalapatis)
- Improve verifier tracking of register bounds in min/max and tnum
domains (Harishankar Vishwanathan, Paul Chaignon, Hao Sun)
- Further extend support for implicit arguments in the verifier (Ihor
Solodrai)
- Add support for nop,nop5 instruction combo for USDT probes in libbpf
(Jiri Olsa)
- Support merging multiple module BTFs (Josef Bacik)
- Extend applicability of bpf_kptr_xchg (Kaitao Cheng)
- Retire rcu_trace_implies_rcu_gp() (Kumar Kartikeya Dwivedi)
- Support variable offset context access for 'syscall' programs (Kumar
Kartikeya Dwivedi)
- Migrate bpf_task_work and dynptr to kmalloc_nolock() (Mykyta
Yatsenko)
- Fix UAF in in open-coded task_vma iterator (Puranjay Mohan)
* tag 'bpf-next-7.1' of git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next: (241 commits)
selftests/bpf: cover short IPv4/IPv6 inputs with adjust_room
bpf: reject short IPv4/IPv6 inputs in bpf_prog_test_run_skb
selftests/bpf: Use memfd_create instead of shm_open in cgroup_iter_memcg
selftests/bpf: Add test for cgroup storage OOB read
bpf: Fix OOB in pcpu_init_value
selftests/bpf: Fix reg_bounds to match new tnum-based refinement
selftests/bpf: Add tests for non-arena/arena operations
bpf: Allow instructions with arena source and non-arena dest registers
bpftool: add missing fsession to the usage and docs of bpftool
docs/bpf: add missing fsession attach type to docs
bpf: add missing fsession to the verifier log
bpf: Move BTF checking logic into check_btf.c
bpf: Move backtracking logic to backtrack.c
bpf: Move state equivalence logic to states.c
bpf: Move check_cfg() into cfg.c
bpf: Move compute_insn_live_regs() into liveness.c
bpf: Move fixup/post-processing logic from verifier.c into fixups.c
bpf: Simplify do_check_insn()
bpf: Move checks for reserved fields out of the main pass
bpf: Delete unused variable
...
Kernel symbol flags:
- Replace the separate *_gpl symbol sections (__ksymtab_gpl and
__kcrctab_gpl) with a unified symbol table and a new
__kflagstab section. This section stores symbol flags, such as
the GPL-only flag, as an 8-bit bitset for each exported symbol.
This is a cleanup that simplifies symbol lookup in the module
loader by avoiding table fragmentation and will allow a cleaner
way to add more flags later if needed.
Module signature UAPI:
- Move struct module_signature to the UAPI headers to allow reuse
by tools outside the kernel proper, such as kmod and
scripts/sign-file. This also renames a few constants for clarity
and drops unused signature types as preparation for hash-based
module integrity checking work that's in progress.
Sysfs:
- Add a /sys/module/<module>/import_ns sysfs attribute to show
the symbol namespaces imported by loaded modules. This makes it
easier to verify driver API access at runtime on systems that
care about such things (e.g. Android).
Cleanups and fixes:
- Force sh_addr to 0 for all sections in module.lds. This prevents
non-zero section addresses when linking modules with ld.bfd -r,
which confused elfutils.
- Fix a memory leak of charp module parameters on module unload
when the kernel is configured with CONFIG_SYSFS=n.
- Override the -EEXIST error code returned by module_init() to
userspace. This prevents confusion with the errno reserved by
the module loader to indicate that a module is already loaded.
- Simplify the warning message and drop the stack dump on positive
returns from module_init().
- Drop unnecessary extern keywords from function declarations and
synchronize parse_args() arguments with their implementation.
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
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Merge tag 'modules-7.1-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/modules/linux
Pull module updates from Sami Tolvanen:
"Kernel symbol flags:
- Replace the separate *_gpl symbol sections (__ksymtab_gpl and
__kcrctab_gpl) with a unified symbol table and a new __kflagstab
section.
This section stores symbol flags, such as the GPL-only flag, as an
8-bit bitset for each exported symbol. This is a cleanup that
simplifies symbol lookup in the module loader by avoiding table
fragmentation and will allow a cleaner way to add more flags later
if needed.
Module signature UAPI:
- Move struct module_signature to the UAPI headers to allow reuse by
tools outside the kernel proper, such as kmod and
scripts/sign-file.
This also renames a few constants for clarity and drops unused
signature types as preparation for hash-based module integrity
checking work that's in progress.
Sysfs:
- Add a /sys/module/<module>/import_ns sysfs attribute to show the
symbol namespaces imported by loaded modules.
This makes it easier to verify driver API access at runtime on
systems that care about such things (e.g. Android).
Cleanups and fixes:
- Force sh_addr to 0 for all sections in module.lds. This prevents
non-zero section addresses when linking modules with 'ld.bfd -r',
which confused elfutils.
- Fix a memory leak of charp module parameters on module unload when
the kernel is configured with CONFIG_SYSFS=n.
- Override the -EEXIST error code returned by module_init() to
userspace. This prevents confusion with the errno reserved by the
module loader to indicate that a module is already loaded.
- Simplify the warning message and drop the stack dump on positive
returns from module_init().
- Drop unnecessary extern keywords from function declarations and
synchronize parse_args() arguments with their implementation"
* tag 'modules-7.1-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/modules/linux: (23 commits)
module: Simplify warning on positive returns from module_init()
module: Override -EEXIST module return
documentation: remove references to *_gpl sections
module: remove *_gpl sections from vmlinux and modules
module: deprecate usage of *_gpl sections in module loader
module: use kflagstab instead of *_gpl sections
module: populate kflagstab in modpost
module: add kflagstab section to vmlinux and modules
module: define ksym_flags enumeration to represent kernel symbol flags
selftests/bpf: verify_pkcs7_sig: Use 'struct module_signature' from the UAPI headers
sign-file: use 'struct module_signature' from the UAPI headers
tools uapi headers: add linux/module_signature.h
module: Move 'struct module_signature' to UAPI
module: Give MODULE_SIG_STRING a more descriptive name
module: Give 'enum pkey_id_type' a more specific name
module: Drop unused signature types
extract-cert: drop unused definition of PKEY_ID_PKCS7
docs: symbol-namespaces: mention sysfs attribute
module: expose imported namespaces via sysfs
module: Remove extern keyword from param prototypes
...
Core features:
- Add support for FEAT_LSUI, allowing futex atomic operations without
toggling Privileged Access Never (PAN)
- Further refactor the arm64 exception handling code towards the
generic entry infrastructure
- Optimise __READ_ONCE() with CONFIG_LTO=y and allow alias analysis
through it
Memory management:
- Refactor the arm64 TLB invalidation API and implementation for better
control over barrier placement and level-hinted invalidation
- Enable batched TLB flushes during memory hot-unplug
- Fix rodata=full block mapping support for realm guests (when
BBML2_NOABORT is available)
Perf and PMU:
- Add support for a whole bunch of system PMUs featured in NVIDIA's
Tegra410 SoC (cspmu extensions for the fabric and PCIe, new drivers
for CPU/C2C memory latency PMUs)
- Clean up iomem resource handling in the Arm CMN driver
- Fix signedness handling of AA64DFR0.{PMUVer,PerfMon}
MPAM (Memory Partitioning And Monitoring):
- Add architecture context-switch and hiding of the feature from KVM
- Add interface to allow MPAM to be exposed to user-space using resctrl
- Add errata workaround for some existing platforms
- Add documentation for using MPAM and what shape of platforms can use
resctrl
Miscellaneous:
- Check DAIF (and PMR, where relevant) at task-switch time
- Skip TFSR_EL1 checks and barriers in synchronous MTE tag check mode
(only relevant to asynchronous or asymmetric tag check modes)
- Remove a duplicate allocation in the kexec code
- Remove redundant save/restore of SCS SP on entry to/from EL0
- Generate the KERNEL_HWCAP_ definitions from the arm64 hwcap
descriptions
- Add kselftest coverage for cmpbr_sigill()
- Update sysreg definitions
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Merge tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux
Pull arm64 updates from Catalin Marinas:
"The biggest changes are MPAM enablement in drivers/resctrl and new PMU
support under drivers/perf.
On the core side, FEAT_LSUI lets futex atomic operations with EL0
permissions, avoiding PAN toggling.
The rest is mostly TLB invalidation refactoring, further generic entry
work, sysreg updates and a few fixes.
Core features:
- Add support for FEAT_LSUI, allowing futex atomic operations without
toggling Privileged Access Never (PAN)
- Further refactor the arm64 exception handling code towards the
generic entry infrastructure
- Optimise __READ_ONCE() with CONFIG_LTO=y and allow alias analysis
through it
Memory management:
- Refactor the arm64 TLB invalidation API and implementation for
better control over barrier placement and level-hinted invalidation
- Enable batched TLB flushes during memory hot-unplug
- Fix rodata=full block mapping support for realm guests (when
BBML2_NOABORT is available)
Perf and PMU:
- Add support for a whole bunch of system PMUs featured in NVIDIA's
Tegra410 SoC (cspmu extensions for the fabric and PCIe, new drivers
for CPU/C2C memory latency PMUs)
- Clean up iomem resource handling in the Arm CMN driver
- Fix signedness handling of AA64DFR0.{PMUVer,PerfMon}
MPAM (Memory Partitioning And Monitoring):
- Add architecture context-switch and hiding of the feature from KVM
- Add interface to allow MPAM to be exposed to user-space using
resctrl
- Add errata workaround for some existing platforms
- Add documentation for using MPAM and what shape of platforms can
use resctrl
Miscellaneous:
- Check DAIF (and PMR, where relevant) at task-switch time
- Skip TFSR_EL1 checks and barriers in synchronous MTE tag check mode
(only relevant to asynchronous or asymmetric tag check modes)
- Remove a duplicate allocation in the kexec code
- Remove redundant save/restore of SCS SP on entry to/from EL0
- Generate the KERNEL_HWCAP_ definitions from the arm64 hwcap
descriptions
- Add kselftest coverage for cmpbr_sigill()
- Update sysreg definitions"
* tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux: (109 commits)
arm64: rsi: use linear-map alias for realm config buffer
arm64: Kconfig: fix duplicate word in CMDLINE help text
arm64: mte: Skip TFSR_EL1 checks and barriers in synchronous tag check mode
arm64/sysreg: Update ID_AA64SMFR0_EL1 description to DDI0601 2025-12
arm64/sysreg: Update ID_AA64ZFR0_EL1 description to DDI0601 2025-12
arm64/sysreg: Update ID_AA64FPFR0_EL1 description to DDI0601 2025-12
arm64/sysreg: Update ID_AA64ISAR2_EL1 description to DDI0601 2025-12
arm64/sysreg: Update ID_AA64ISAR0_EL1 description to DDI0601 2025-12
arm64/hwcap: Generate the KERNEL_HWCAP_ definitions for the hwcaps
arm64: kexec: Remove duplicate allocation for trans_pgd
ACPI: AGDI: fix missing newline in error message
arm64: Check DAIF (and PMR) at task-switch time
arm64: entry: Use split preemption logic
arm64: entry: Use irqentry_{enter_from,exit_to}_kernel_mode()
arm64: entry: Consistently prefix arm64-specific wrappers
arm64: entry: Don't preempt with SError or Debug masked
entry: Split preemption from irqentry_exit_to_kernel_mode()
entry: Split kernel mode logic from irqentry_{enter,exit}()
entry: Move irqentry_enter() prototype later
entry: Remove local_irq_{enable,disable}_exit_to_user()
...
Fair scheduling updates:
- Skip SCHED_IDLE rq for SCHED_IDLE tasks (Christian Loehle)
- Remove superfluous rcu_read_lock() in the wakeup path (K Prateek Nayak)
- Simplify the entry condition for update_idle_cpu_scan() (K Prateek Nayak)
- Simplify SIS_UTIL handling in select_idle_cpu() (K Prateek Nayak)
- Avoid overflow in enqueue_entity() (K Prateek Nayak)
- Update overutilized detection (Vincent Guittot)
- Prevent negative lag increase during delayed dequeue (Vincent Guittot)
- Clear buddies for preempt_short (Vincent Guittot)
- Implement more complex proportional newidle balance (Peter Zijlstra)
- Increase weight bits for avg_vruntime (Peter Zijlstra)
- Use full weight to __calc_delta() (Peter Zijlstra)
RT and DL scheduling updates:
- Fix incorrect schedstats for rt and dl thread (Dengjun Su)
- Skip group schedulable check with rt_group_sched=0 (Michal Koutný)
- Move group schedulability check to sched_rt_global_validate()
(Michal Koutný)
- Add reporting of runtime left & abs deadline to sched_getattr()
for DEADLINE tasks (Tommaso Cucinotta)
Scheduling topology updates by K Prateek Nayak:
- Compute sd_weight considering cpuset partitions
- Extract "imb_numa_nr" calculation into a separate helper
- Allocate per-CPU sched_domain_shared in s_data
- Switch to assigning "sd->shared" from s_data
- Remove sched_domain_shared allocation with sd_data
Energy-aware scheduling updates:
- Filter false overloaded_group case for EAS (Vincent Guittot)
- PM: EM: Switch to rcu_dereference_all() in wakeup path
(Dietmar Eggemann)
Infrastructure updates:
- Replace use of system_unbound_wq with system_dfl_wq (Marco Crivellari)
Proxy scheduling updates by John Stultz:
- Make class_schedulers avoid pushing current, and get rid of proxy_tag_curr()
- Minimise repeated sched_proxy_exec() checking
- Fix potentially missing balancing with Proxy Exec
- Fix and improve task::blocked_on et al handling
- Add assert_balance_callbacks_empty() helper
- Add logic to zap balancing callbacks if we pick again
- Move attach_one_task() and attach_task() helpers to sched.h
- Handle blocked-waiter migration (and return migration)
- Add K Prateek Nayak to scheduler reviewers for proxy execution
Misc cleanups and fixes by John Stultz, Joseph Salisbury,
Peter Zijlstra, K Prateek Nayak, Michal Koutný, Randy Dunlap,
Shrikanth Hegde, Vincent Guittot, Zhan Xusheng, Xie Yuanbin
and Vincent Guittot.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'sched-core-2026-04-13' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler updates from Ingo Molnar:
"Fair scheduling updates:
- Skip SCHED_IDLE rq for SCHED_IDLE tasks (Christian Loehle)
- Remove superfluous rcu_read_lock() in the wakeup path (K Prateek Nayak)
- Simplify the entry condition for update_idle_cpu_scan() (K Prateek Nayak)
- Simplify SIS_UTIL handling in select_idle_cpu() (K Prateek Nayak)
- Avoid overflow in enqueue_entity() (K Prateek Nayak)
- Update overutilized detection (Vincent Guittot)
- Prevent negative lag increase during delayed dequeue (Vincent Guittot)
- Clear buddies for preempt_short (Vincent Guittot)
- Implement more complex proportional newidle balance (Peter Zijlstra)
- Increase weight bits for avg_vruntime (Peter Zijlstra)
- Use full weight to __calc_delta() (Peter Zijlstra)
RT and DL scheduling updates:
- Fix incorrect schedstats for rt and dl thread (Dengjun Su)
- Skip group schedulable check with rt_group_sched=0 (Michal Koutný)
- Move group schedulability check to sched_rt_global_validate()
(Michal Koutný)
- Add reporting of runtime left & abs deadline to sched_getattr()
for DEADLINE tasks (Tommaso Cucinotta)
Scheduling topology updates by K Prateek Nayak:
- Compute sd_weight considering cpuset partitions
- Extract "imb_numa_nr" calculation into a separate helper
- Allocate per-CPU sched_domain_shared in s_data
- Switch to assigning "sd->shared" from s_data
- Remove sched_domain_shared allocation with sd_data
Energy-aware scheduling updates:
- Filter false overloaded_group case for EAS (Vincent Guittot)
- PM: EM: Switch to rcu_dereference_all() in wakeup path
(Dietmar Eggemann)
Infrastructure updates:
- Replace use of system_unbound_wq with system_dfl_wq (Marco Crivellari)
Proxy scheduling updates by John Stultz:
- Make class_schedulers avoid pushing current, and get rid of proxy_tag_curr()
- Minimise repeated sched_proxy_exec() checking
- Fix potentially missing balancing with Proxy Exec
- Fix and improve task::blocked_on et al handling
- Add assert_balance_callbacks_empty() helper
- Add logic to zap balancing callbacks if we pick again
- Move attach_one_task() and attach_task() helpers to sched.h
- Handle blocked-waiter migration (and return migration)
- Add K Prateek Nayak to scheduler reviewers for proxy execution
Misc cleanups and fixes by John Stultz, Joseph Salisbury, Peter
Zijlstra, K Prateek Nayak, Michal Koutný, Randy Dunlap, Shrikanth
Hegde, Vincent Guittot, Zhan Xusheng, Xie Yuanbin and Vincent Guittot"
* tag 'sched-core-2026-04-13' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (46 commits)
sched/eevdf: Clear buddies for preempt_short
sched/rt: Cleanup global RT bandwidth functions
sched/rt: Move group schedulability check to sched_rt_global_validate()
sched/rt: Skip group schedulable check with rt_group_sched=0
sched/fair: Avoid overflow in enqueue_entity()
sched: Use u64 for bandwidth ratio calculations
sched/fair: Prevent negative lag increase during delayed dequeue
sched/fair: Use sched_energy_enabled()
sched: Handle blocked-waiter migration (and return migration)
sched: Move attach_one_task and attach_task helpers to sched.h
sched: Add logic to zap balance callbacks if we pick again
sched: Add assert_balance_callbacks_empty helper
sched/locking: Add special p->blocked_on==PROXY_WAKING value for proxy return-migration
sched: Fix modifying donor->blocked on without proper locking
locking: Add task::blocked_lock to serialize blocked_on state
sched: Fix potentially missing balancing with Proxy Exec
sched: Minimise repeated sched_proxy_exec() checking
sched: Make class_schedulers avoid pushing current, and get rid of proxy_tag_curr()
MAINTAINERS: Add K Prateek Nayak to scheduler reviewers
sched/core: Get this cpu once in ttwu_queue_cond()
...
Core updates:
- Try to allocate task_ctx_data quickly, to optimize
O(N^2) algorithm on large systems with O(100k) threads
(Namhyung Kim)
AMD PMU driver IBS support updates and fixes, by Ravi Bangoria:
- Fix interrupt accounting for discarded samples
- Fix a Zen5-specific quirk
- Fix PhyAddrVal handling
- Fix NMI-safety with perf_allow_kernel()
- Fix a race between event add and NMIs
Intel PMU driver updates:
- Only check GP counters for PEBS constraints validation (Dapeng Mi)
MSR driver:
- Turn SMI_COUNT and PPERF on by default, instead of a long
list of CPU models to enable them on (Kan Liang)
Misc cleanups and fixes by Aldf Conte, Anshuman Khandual, Namhyung Kim,
Ravi Bangoria and Yen-Hsiang Hsu.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'perf-core-2026-04-13' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull performance events updates from Ingo Molnar:
"Core updates:
- Try to allocate task_ctx_data quickly, to optimize O(N^2) algorithm
on large systems with O(100k) threads (Namhyung Kim)
AMD PMU driver IBS support updates and fixes, by Ravi Bangoria:
- Fix interrupt accounting for discarded samples
- Fix a Zen5-specific quirk
- Fix PhyAddrVal handling
- Fix NMI-safety with perf_allow_kernel()
- Fix a race between event add and NMIs
Intel PMU driver updates:
- Only check GP counters for PEBS constraints validation (Dapeng Mi)
MSR driver:
- Turn SMI_COUNT and PPERF on by default, instead of a long list of
CPU models to enable them on (Kan Liang)
... and misc cleanups and fixes by Aldf Conte, Anshuman Khandual,
Namhyung Kim, Ravi Bangoria and Yen-Hsiang Hsu"
* tag 'perf-core-2026-04-13' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
perf/events: Replace READ_ONCE() with standard pgtable accessors
perf/x86/msr: Make SMI and PPERF on by default
perf/x86/intel/p4: Fix unused variable warning in p4_pmu_init()
perf/x86/intel: Only check GP counters for PEBS constraints validation
perf/x86/amd/ibs: Fix comment typo in ibs_op_data
perf/amd/ibs: Advertise remote socket capability
perf/amd/ibs: Enable streaming store filter
perf/amd/ibs: Enable RIP bit63 hardware filtering
perf/amd/ibs: Enable fetch latency filtering
perf/amd/ibs: Support IBS_{FETCH|OP}_CTL2[Dis] to eliminate RMW race
perf/amd/ibs: Add new MSRs and CPUID bits definitions
perf/amd/ibs: Define macro for ldlat mask and shift
perf/amd/ibs: Avoid race between event add and NMI
perf/amd/ibs: Avoid calling perf_allow_kernel() from the IBS NMI handler
perf/amd/ibs: Preserve PhyAddrVal bit when clearing PhyAddr MSR
perf/amd/ibs: Limit ldlat->l3missonly dependency to Zen5
perf/amd/ibs: Account interrupt for discarded samples
perf/core: Simplify __detach_global_ctx_data()
perf/core: Try to allocate task_ctx_data quickly
perf/core: Pass GFP flags to attach_task_ctx_data()
Mutexes:
- Add killable flavor to guard definitions (Davidlohr Bueso)
- Remove the list_head from struct mutex (Matthew Wilcox)
- Rename mutex_init_lockep() (Davidlohr Bueso)
rwsems:
- Remove the list_head from struct rw_semaphore and
replace it with a single pointer (Matthew Wilcox)
- Fix logic error in rwsem_del_waiter() (Andrei Vagin)
Semaphores:
- Remove the list_head from struct semaphore (Matthew Wilcox)
Jump labels:
- Use ATOMIC_INIT() for initialization of .enabled (Thomas Weißschuh)
- Remove workaround for old compilers in initializations
(Thomas Weißschuh)
Lock context analysis changes and improvements:
- Add context analysis for rwsems (Peter Zijlstra)
- Fix rwlock and spinlock lock context annotations (Bart Van Assche)
- Fix rwlock support in <linux/spinlock_up.h> (Bart Van Assche)
- Add lock context annotations in the spinlock implementation
(Bart Van Assche)
- signal: Fix the lock_task_sighand() annotation (Bart Van Assche)
- ww-mutex: Fix the ww_acquire_ctx function annotations
(Bart Van Assche)
- Add lock context support in do_raw_{read,write}_trylock()
(Bart Van Assche)
- arm64, compiler-context-analysis: Permit alias analysis through
__READ_ONCE() with CONFIG_LTO=y (Marco Elver)
- Add __cond_releases() (Peter Zijlstra)
- Add context analysis for mutexes (Peter Zijlstra)
- Add context analysis for rtmutexes (Peter Zijlstra)
- Convert futexes to compiler context analysis (Peter Zijlstra)
Rust integration updates:
- Add atomic fetch_sub() implementation (Andreas Hindborg)
- Refactor various rust_helper_ methods for expansion (Boqun Feng)
- Add Atomic<*{mut,const} T> support (Boqun Feng)
- Add atomic operation helpers over raw pointers (Boqun Feng)
- Add performance-optimal Flag type for atomic booleans, to avoid
slow byte-sized RMWs on architectures that don't support them.
(FUJITA Tomonori)
- Misc cleanups and fixes (Andreas Hindborg, Boqun Feng,
FUJITA Tomonori)
LTO support updates:
- arm64: Optimize __READ_ONCE() with CONFIG_LTO=y (Marco Elver)
- compiler: Simplify generic RELOC_HIDE() (Marco Elver)
Miscellaneous fixes and cleanups by Peter Zijlstra, Randy Dunlap,
Thomas Weißschuh, Davidlohr Bueso and Mikhail Gavrilov.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'locking-core-2026-04-13' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull locking updates from Ingo Molnar:
"Mutexes:
- Add killable flavor to guard definitions (Davidlohr Bueso)
- Remove the list_head from struct mutex (Matthew Wilcox)
- Rename mutex_init_lockep() (Davidlohr Bueso)
rwsems:
- Remove the list_head from struct rw_semaphore and
replace it with a single pointer (Matthew Wilcox)
- Fix logic error in rwsem_del_waiter() (Andrei Vagin)
Semaphores:
- Remove the list_head from struct semaphore (Matthew Wilcox)
Jump labels:
- Use ATOMIC_INIT() for initialization of .enabled (Thomas Weißschuh)
- Remove workaround for old compilers in initializations
(Thomas Weißschuh)
Lock context analysis changes and improvements:
- Add context analysis for rwsems (Peter Zijlstra)
- Fix rwlock and spinlock lock context annotations (Bart Van Assche)
- Fix rwlock support in <linux/spinlock_up.h> (Bart Van Assche)
- Add lock context annotations in the spinlock implementation
(Bart Van Assche)
- signal: Fix the lock_task_sighand() annotation (Bart Van Assche)
- ww-mutex: Fix the ww_acquire_ctx function annotations
(Bart Van Assche)
- Add lock context support in do_raw_{read,write}_trylock()
(Bart Van Assche)
- arm64, compiler-context-analysis: Permit alias analysis through
__READ_ONCE() with CONFIG_LTO=y (Marco Elver)
- Add __cond_releases() (Peter Zijlstra)
- Add context analysis for mutexes (Peter Zijlstra)
- Add context analysis for rtmutexes (Peter Zijlstra)
- Convert futexes to compiler context analysis (Peter Zijlstra)
Rust integration updates:
- Add atomic fetch_sub() implementation (Andreas Hindborg)
- Refactor various rust_helper_ methods for expansion (Boqun Feng)
- Add Atomic<*{mut,const} T> support (Boqun Feng)
- Add atomic operation helpers over raw pointers (Boqun Feng)
- Add performance-optimal Flag type for atomic booleans, to avoid
slow byte-sized RMWs on architectures that don't support them.
(FUJITA Tomonori)
- Misc cleanups and fixes (Andreas Hindborg, Boqun Feng, FUJITA
Tomonori)
LTO support updates:
- arm64: Optimize __READ_ONCE() with CONFIG_LTO=y (Marco Elver)
- compiler: Simplify generic RELOC_HIDE() (Marco Elver)
Miscellaneous fixes and cleanups by Peter Zijlstra, Randy Dunlap,
Thomas Weißschuh, Davidlohr Bueso and Mikhail Gavrilov"
* tag 'locking-core-2026-04-13' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (39 commits)
compiler: Simplify generic RELOC_HIDE()
locking: Add lock context annotations in the spinlock implementation
locking: Add lock context support in do_raw_{read,write}_trylock()
locking: Fix rwlock support in <linux/spinlock_up.h>
lockdep: Raise default stack trace limits when KASAN is enabled
cleanup: Optimize guards
jump_label: remove workaround for old compilers in initializations
jump_label: use ATOMIC_INIT() for initialization of .enabled
futex: Convert to compiler context analysis
locking/rwsem: Fix logic error in rwsem_del_waiter()
locking/rwsem: Add context analysis
locking/rtmutex: Add context analysis
locking/mutex: Add context analysis
compiler-context-analysys: Add __cond_releases()
locking/mutex: Remove the list_head from struct mutex
locking/semaphore: Remove the list_head from struct semaphore
locking/rwsem: Remove the list_head from struct rw_semaphore
rust: atomic: Update a safety comment in impl of `fetch_add()`
rust: sync: atomic: Update documentation for `fetch_add()`
rust: sync: atomic: Add fetch_sub()
...
- Switch smp_call_on_cpu() to user system_percpu_wq instead of system_wq
a part of the ongoing workqueue restructuring
- Improve the CSD-lock diagnostics for smp_call_function_single() to
provide better debug mechanisms on weakly ordered systems.
- Cache the current CPU number once in smp_call_function*() instead of
retrieving it over and over.
- Add missing kernel-doc comments all over the place
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Merge tag 'smp-core-2026-04-12' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull SMP core updates from Thomas Gleixner:
- Switch smp_call_on_cpu() to user system_percpu_wq instead of
system_wq a part of the ongoing workqueue restructuring
- Improve the CSD-lock diagnostics for smp_call_function_single() to
provide better debug mechanisms on weakly ordered systems.
- Cache the current CPU number once in smp_call_function*() instead of
retrieving it over and over.
- Add missing kernel-doc comments all over the place
* tag 'smp-core-2026-04-12' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
smp: Use system_percpu_wq instead of system_wq
smp: Improve smp_call_function_single() CSD-lock diagnostics
smp: Get this_cpu once in smp_call_function
smp: Add missing kernel-doc comments
- Make the handling of compat functions consistent and more robust
- Rework the underlying data store so that it is dynamically
allocated, which allows the conversion of the last holdout SPARC64
to the generic VDSO implementation
- Rework the SPARC64 VDSO to utilize the generic implementation
- Mop up the left overs of the non-generic VDSO support in the core
code.
- Expand the VDSO selftest and make them more robust
- Allow time namespaces to be enabled independently of the generic
VDSO support, which was not possible before due to SPARC64 not
using it.
- Various cleanups and improvements in the related code.
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Merge tag 'timers-vdso-2026-04-12' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull vdso updates from Thomas Gleixner:
- Make the handling of compat functions consistent and more robust
- Rework the underlying data store so that it is dynamically allocated,
which allows the conversion of the last holdout SPARC64 to the
generic VDSO implementation
- Rework the SPARC64 VDSO to utilize the generic implementation
- Mop up the left overs of the non-generic VDSO support in the core
code
- Expand the VDSO selftest and make them more robust
- Allow time namespaces to be enabled independently of the generic VDSO
support, which was not possible before due to SPARC64 not using it
- Various cleanups and improvements in the related code
* tag 'timers-vdso-2026-04-12' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (51 commits)
timens: Use task_lock guard in timens_get*()
timens: Use mutex guard in proc_timens_set_offset()
timens: Simplify some calls to put_time_ns()
timens: Add a __free() wrapper for put_time_ns()
timens: Remove dependency on the vDSO
vdso/timens: Move functions to new file
selftests: vDSO: vdso_test_correctness: Add a test for time()
selftests: vDSO: vdso_test_correctness: Use facilities from parse_vdso.c
selftests: vDSO: vdso_test_correctness: Handle different tv_usec types
selftests: vDSO: vdso_test_correctness: Drop SYS_getcpu fallbacks
selftests: vDSO: vdso_test_gettimeofday: Remove nolibc checks
Revert "selftests: vDSO: parse_vdso: Use UAPI headers instead of libc headers"
random: vDSO: Remove ifdeffery
random: vDSO: Trim vDSO includes
vdso/datapage: Trim down unnecessary includes
vdso/datapage: Remove inclusion of gettimeofday.h
vdso/helpers: Explicitly include vdso/processor.h
vdso/gettimeofday: Add explicit includes
random: vDSO: Add explicit includes
MIPS: vdso: Explicitly include asm/vdso/vdso.h
...
- A rework of the hrtimer subsystem to reduce the overhead for frequently
armed timers, especially the hrtick scheduler timer.
- Better timer locality decision
- Simplification of the evaluation of the first expiry time by
keeping track of the neighbor timers in the RB-tree by providing a
RB-tree variant with neighbor links. That avoids walking the
RB-tree on removal to find the next expiry time, but even more
important allows to quickly evaluate whether a timer which is
rearmed changes the position in the RB-tree with the modified
expiry time or not. If not, the dequeue/enqueue sequence which both
can end up in rebalancing can be completely avoided.
- Deferred reprogramming of the underlying clock event device. This
optimizes for the situation where a hrtimer callback sets the need
resched bit. In that case the code attempts to defer the
re-programming of the clock event device up to the point where the
scheduler has picked the next task and has the next hrtick timer
armed. In case that there is no immediate reschedule or soft
interrupts have to be handled before reaching the reschedule point
in the interrupt entry code the clock event is reprogrammed in one
of those code paths to prevent that the timer becomes stale.
- Support for clocksource coupled clockevents
The TSC deadline timer is coupled to the TSC. The next event is
programmed in TSC time. Currently this is done by converting the
CLOCK_MONOTONIC based expiry value into a relative timeout,
converting it into TSC ticks, reading the TSC adding the delta
ticks and writing the deadline MSR.
As the timekeeping core has the conversion factors for the TSC
already, the whole back and forth conversion can be completely
avoided. The timekeeping core calculates the reverse conversion
factors from nanoseconds to TSC ticks and utilizes the base
timestamps of TSC and CLOCK_MONOTONIC which are updated once per
tick. This allows a direct conversion into the TSC deadline value
without reading the time and as a bonus keeps the deadline
conversion in sync with the TSC conversion factors, which are
updated by adjtimex() on systems with NTP/PTP enabled.
- Allow inlining of the clocksource read and clockevent write
functions when they are tiny enough, e.g. on x86 RDTSC and WRMSR.
With all those enhancements in place a hrtick enabled scheduler
provides the same performance as without hrtick. But also other hrtimer
users obviously benefit from these optimizations.
- Robustness improvements and cleanups of historical sins in the hrtimer
and timekeeping code.
- Rewrite of the clocksource watchdog.
The clocksource watchdog code has over time reached the state of an
impenetrable maze of duct tape and staples. The original design, which was
made in the context of systems far smaller than today, is based on the
assumption that the to be monitored clocksource (TSC) can be trivially
compared against a known to be stable clocksource (HPET/ACPI-PM timer).
Over the years this rather naive approach turned out to have major
flaws. Long delays between the watchdog invocations can cause wrap
arounds of the reference clocksource. The access to the reference
clocksource degrades on large multi-sockets systems dure to
interconnect congestion. This has been addressed with various
heuristics which degraded the accuracy of the watchdog to the point
that it fails to detect actual TSC problems on older hardware which
exposes slow inter CPU drifts due to firmware manipulating the TSC to
hide SMI time.
The rewrite addresses this by:
- Restricting the validation against the reference clocksource to the
boot CPU which is usually closest to the legacy block which
contains the reference clocksource (HPET/ACPI-PM).
- Do a round robin validation betwen the boot CPU and the other CPUs
based only on the TSC with an algorithm similar to the TSC
synchronization code during CPU hotplug.
- Being more leniant versus remote timeouts
- The usual tiny fixes, cleanups and enhancements all over the place
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Merge tag 'timers-core-2026-04-12' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull timer core updates from Thomas Gleixner:
- A rework of the hrtimer subsystem to reduce the overhead for
frequently armed timers, especially the hrtick scheduler timer:
- Better timer locality decision
- Simplification of the evaluation of the first expiry time by
keeping track of the neighbor timers in the RB-tree by providing
a RB-tree variant with neighbor links. That avoids walking the
RB-tree on removal to find the next expiry time, but even more
important allows to quickly evaluate whether a timer which is
rearmed changes the position in the RB-tree with the modified
expiry time or not. If not, the dequeue/enqueue sequence which
both can end up in rebalancing can be completely avoided.
- Deferred reprogramming of the underlying clock event device. This
optimizes for the situation where a hrtimer callback sets the
need resched bit. In that case the code attempts to defer the
re-programming of the clock event device up to the point where
the scheduler has picked the next task and has the next hrtick
timer armed. In case that there is no immediate reschedule or
soft interrupts have to be handled before reaching the reschedule
point in the interrupt entry code the clock event is reprogrammed
in one of those code paths to prevent that the timer becomes
stale.
- Support for clocksource coupled clockevents
The TSC deadline timer is coupled to the TSC. The next event is
programmed in TSC time. Currently this is done by converting the
CLOCK_MONOTONIC based expiry value into a relative timeout,
converting it into TSC ticks, reading the TSC adding the delta
ticks and writing the deadline MSR.
As the timekeeping core has the conversion factors for the TSC
already, the whole back and forth conversion can be completely
avoided. The timekeeping core calculates the reverse conversion
factors from nanoseconds to TSC ticks and utilizes the base
timestamps of TSC and CLOCK_MONOTONIC which are updated once per
tick. This allows a direct conversion into the TSC deadline value
without reading the time and as a bonus keeps the deadline
conversion in sync with the TSC conversion factors, which are
updated by adjtimex() on systems with NTP/PTP enabled.
- Allow inlining of the clocksource read and clockevent write
functions when they are tiny enough, e.g. on x86 RDTSC and WRMSR.
With all those enhancements in place a hrtick enabled scheduler
provides the same performance as without hrtick. But also other
hrtimer users obviously benefit from these optimizations.
- Robustness improvements and cleanups of historical sins in the
hrtimer and timekeeping code.
- Rewrite of the clocksource watchdog.
The clocksource watchdog code has over time reached the state of an
impenetrable maze of duct tape and staples. The original design,
which was made in the context of systems far smaller than today, is
based on the assumption that the to be monitored clocksource (TSC)
can be trivially compared against a known to be stable clocksource
(HPET/ACPI-PM timer).
Over the years this rather naive approach turned out to have major
flaws. Long delays between the watchdog invocations can cause wrap
arounds of the reference clocksource. The access to the reference
clocksource degrades on large multi-sockets systems dure to
interconnect congestion. This has been addressed with various
heuristics which degraded the accuracy of the watchdog to the point
that it fails to detect actual TSC problems on older hardware which
exposes slow inter CPU drifts due to firmware manipulating the TSC to
hide SMI time.
The rewrite addresses this by:
- Restricting the validation against the reference clocksource to
the boot CPU which is usually closest to the legacy block which
contains the reference clocksource (HPET/ACPI-PM).
- Do a round robin validation betwen the boot CPU and the other
CPUs based only on the TSC with an algorithm similar to the TSC
synchronization code during CPU hotplug.
- Being more leniant versus remote timeouts
- The usual tiny fixes, cleanups and enhancements all over the place
* tag 'timers-core-2026-04-12' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (75 commits)
alarmtimer: Access timerqueue node under lock in suspend
hrtimer: Fix incorrect #endif comment for BITS_PER_LONG check
posix-timers: Fix stale function name in comment
timers: Get this_cpu once while clearing the idle state
clocksource: Rewrite watchdog code completely
clocksource: Don't use non-continuous clocksources as watchdog
x86/tsc: Handle CLOCK_SOURCE_VALID_FOR_HRES correctly
MIPS: Don't select CLOCKSOURCE_WATCHDOG
parisc: Remove unused clocksource flags
hrtimer: Add a helper to retrieve a hrtimer from its timerqueue node
hrtimer: Remove trailing comma after HRTIMER_MAX_CLOCK_BASES
hrtimer: Mark index and clockid of clock base as const
hrtimer: Drop unnecessary pointer indirection in hrtimer_expire_entry event
hrtimer: Drop spurious space in 'enum hrtimer_base_type'
hrtimer: Don't zero-initialize ret in hrtimer_nanosleep()
hrtimer: Remove hrtimer_get_expires_ns()
timekeeping: Mark offsets array as const
timekeeping/auxclock: Consistently use raw timekeeper for tk_setup_internals()
timer_list: Print offset as signed integer
tracing: Use explicit array size instead of sentinel elements in symbol printing
...
- Invoke add_interrupt_randomness() in handle_percpu_devid_irq() and
cleanup the workaround in the Hyper-V driver, which would now invoke
it twice on ARM64. Removing it from the driver requires to add it to
the x86 system vector entry point.
- Remove the pointles cpu_read_lock() around reading CPU possible mask,
which is read only after init.
- Add documentation for the interaction between device tree bindings and
the interrupt type defines in irq.h.
- Delete stale defines in the matrix allocator and the equivalent in
loongarch.
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Merge tag 'irq-core-2026-04-12' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull core irq updates from Thomas Gleixner:
- Invoke add_interrupt_randomness() in handle_percpu_devid_irq() and
cleanup the workaround in the Hyper-V driver, which would now invoke
it twice on ARM64. Removing it from the driver requires to add it to
the x86 system vector entry point
- Remove the pointles cpu_read_lock() around reading CPU possible mask,
which is read only after init
- Add documentation for the interaction between device tree bindings
and the interrupt type defines in irq.h
- Delete stale defines in the matrix allocator and the equivalent in
loongarch
* tag 'irq-core-2026-04-12' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
Drivers: hv: Move add_interrupt_randomness() to hypervisor callback sysvec
genirq/chip: Invoke add_interrupt_randomness() in handle_percpu_devid_irq()
genirq/affinity: Remove cpus_read_lock() while reading cpu_possible_mask
genirq/matrix, LoongArch: Delete IRQ_MATRIX_BITS leftovers
genirq: Document interaction between <linux/irq.h> and DT binding defines
The syntax for fully-qualified variable references in histograms is
subsys.event.$var, which is parsed correctly, but not displayed correctly
when printing a histogram spec. The current code puts the $ reference at
the beginning of the fully-qualified variable name i.e. $subsys.event.var,
which is incorrect.
Before:
trigger info: hist:keys=next_comm:vals=hitcount:wakeup_lat=common_timestamp.usecs-$sched.sched_wakeup.ts0: ...
After:
trigger info: hist:keys=next_comm:vals=hitcount:wakeup_lat=common_timestamp.usecs-sched.sched_wakeup.$ts0: ...
Link: https://patch.msgid.link/5dee9a86d062a4dd68c2214f3d90ac93811e1951.1776112478.git.zanussi@kernel.org
Signed-off-by: Tom Zanussi <zanussi@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
When a tracepoint goes through the 0 -> 1 transition, tracepoint_add_func()
invokes the subsystem's ext->regfunc() before attempting to install the
new probe via func_add(). If func_add() then fails (for example, when
allocate_probes() cannot allocate a new probe array under memory pressure
and returns -ENOMEM), the function returns the error without calling the
matching ext->unregfunc(), leaving the side effects of regfunc() behind
with no installed probe to justify them.
For syscall tracepoints this is particularly unpleasant: syscall_regfunc()
bumps sys_tracepoint_refcount and sets SYSCALL_TRACEPOINT on every task.
After a leaked failure, the refcount is stuck at a non-zero value with no
consumer, and every task continues paying the syscall trace entry/exit
overhead until reboot. Other subsystems providing regfunc()/unregfunc()
pairs exhibit similarly scoped persistent state.
Mirror the existing 1 -> 0 cleanup and call ext->unregfunc() in the
func_add() error path, gated on the same condition used there so the
unwind is symmetric with the registration.
Fixes: 8cf868affd ("tracing: Have the reg function allow to fail")
Cc: stable@vger.kernel.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Link: https://patch.msgid.link/20260413190601.21993-1-devnexen@gmail.com
Signed-off-by: David Carlier <devnexen@gmail.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
As pointed out by Smatch, the ring-buffer descriptor array page_va is
counted by nr_page_va, but the accessor ring_buffer_desc_page() allows
access off by one.
Currently, this does not cause problems, as the page ID always comes
from a trusted source. Nonetheless, ensure robustness and fix the
accessor. While at it, make the page_id unsigned.
Link: https://patch.msgid.link/20260410124527.3563970-1-vdonnefort@google.com
Reported-by: Dan Carpenter <error27@gmail.com>
Signed-off-by: Vincent Donnefort <vdonnefort@google.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
hist_field_name() uses a static MAX_FILTER_STR_VAL buffer for fully
qualified variable-reference names, but it currently appends into that
buffer with strcat() without rebuilding it first. As a result, repeated
calls append a new "system.event.field" name onto the previous one,
which can eventually run past the end of full_name.
Build the name with snprintf() on each call and return NULL if the fully
qualified name does not fit in MAX_FILTER_STR_VAL.
Link: https://patch.msgid.link/20260401112224.85582-1-pengpeng@iscas.ac.cn
Fixes: 067fe038e7 ("tracing: Add variable reference handling to hist triggers")
Reviewed-by: Tom Zanussi <zanussi@kernel.org>
Tested-by: Tom Zanussi <zanussi@kernel.org>
Signed-off-by: Pengpeng Hou <pengpeng@iscas.ac.cn>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
The header_page tracefs metadata currently reports overwrite as an
int field with size 1. That makes parsers warn about a type and
size mismatch even though the field is only used as a one-byte flag
within commit.
Keep the shared offset with commit as-is, but report overwrite as
char so the declared type matches the hardcoded size. The signedness
is already carried separately by the emitted signed field.
Link: https://patch.msgid.link/20260406165333.46052-1-create0818@163.com
Link: https://bugzilla.kernel.org/show_bug.cgi?id=216999
Signed-off-by: Cao Ruichuang <create0818@163.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
- Update qcom-hw DT bindings to include Eliza hardware (Abel Vesa)
- Update cpufreq-dt-platdev blocklist (Faruque Ansari)
- Minor updates to driver and dt-bindings for Tegra (Thierry Reding,
Rosen Penev)
- Add MAINTAINERS entry for CPPC driver (Viresh Kumar)
- Add support for new features: CPPC performance priority, Dynamic EPP,
Raw EPP, and new unit tests for them to amd-pstate (Gautham Shenoy,
Mario Limonciello)
- Fix sysfs files being present when HW missing and broken/outdated
documentation in the amd-pstate driver (Ninad Naik, Gautham Shenoy)
- Pass the policy to cpufreq_driver->adjust_perf() to avoid using
cpufreq_cpu_get() in the .adjust_perf() callback in amd-pstate which
leads to a scheduling-while-atomic bug (K Prateek Nayak)
- Clean up dead code in Kconfig for cpufreq (Julian Braha)
- Remove max_freq_req update for pre-existing cpufreq policy and add a
boost_freq_req QoS request to save the boost constraint instead of
overwriting the last scaling_max_freq constraint (Pierre Gondois)
- Embed cpufreq QoS freq_req objects in cpufreq policy so they all
are allocated in one go along with the policy to simplify lifetime
rules and avoid error handling issues (Viresh Kumar)
- Use DMI max speed when CPPC is unavailable in the acpi-cpufreq
scaling driver (Henry Tseng)
- Switch policy_is_shared() in cpufreq to using cpumask_nth() instead
of cpumask_weight() because the former is more efficient (Yury Norov)
- Use sysfs_emit() in sysfs show functions for cpufreq governor
attributes (Thorsten Blum)
- Update intel_pstate to stop returning an error when "off" is written
to its status sysfs attribute while the driver is already off (Fabio
De Francesco)
- Include current frequency in the debug message printed by
__cpufreq_driver_target() (Pengjie Zhang)
- Refine stopped tick handling in the menu cpuidle governor and
rearrange stopped tick handling in the teo cpuidle governor (Rafael
Wysocki)
- Add Panther Lake C-states table to the intel_idle driver (Artem
Bityutskiy)
- Clean up dead dependencies on CPU_IDLE in Kconfig (Julian Braha)
- Simplify cpuidle_register_device() with guard() (Huisong Li)
- Use performance level if available to distinguish between rates in
OPP debugfs (Manivannan Sadhasivam)
- Fix scoped_guard in dev_pm_opp_xlate_required_opp() (Viresh Kumar)
- Return -ENODATA if the snapshot image is not loaded (Alberto Garcia)
- Remove inclusion of crypto/hash.h from hibernate_64.c on x86 (Eric
Biggers)
- Clean up and rearrange the intel_rapl power capping driver to make
the respective interface drivers (TPMI, MSR, and MMOI) hold their
own settings and primitives and consolidate PL4 and PMU support
flags into rapl_defaults (Kuppuswamy Sathyanarayanan)
- Correct kernel-doc function parameter names in the power capping core
code (Randy Dunlap)
- Remove unneeded casting for HZ_PER_KHZ in devfreq (Andy Shevchenko)
- Use _visible attribute to replace create/remove_sysfs_files() in
devfreq (Pengjie Zhang)
- Add Tegra114 support to activity monitor device in tegra30-devfreq as
a preparation to upcoming EMC controller support (Svyatoslav Ryhel)
- Fix mistakes in cpupower man pages, add the boost and epp options to
the cpupower-frequency-info man page, and add the perf-bias option to
the cpupower-info man page (Roberto Ricci)
- Remove unnecessary extern declarations from getopt.h in arguments
parsing functions in cpufreq-set, cpuidle-info, cpuidle-set,
cpupower-info, and cpupower-set utilities (Kaushlendra Kumar)
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Merge tag 'pm-7.1-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm
Pull power management updates from Rafael Wysocki:
"Once again, cpufreq is the most active development area, mostly
because of the new feature additions and documentation updates in the
amd-pstate driver, but there are also changes in the cpufreq core
related to boost support and other assorted updates elsewhere.
Next up are power capping changes due to the major cleanup of the
Intel RAPL driver.
On the cpuidle front, a new C-states table for Intel Panther Lake is
added to the intel_idle driver, the stopped tick handling in the menu
and teo governors is updated, and there are a couple of cleanups.
Apart from the above, support for Tegra114 is added to devfreq and
there are assorted cleanups of that code, there are also two updates
of the operating performance points (OPP) library, two minor updates
related to hibernation, and cpupower utility man pages updates and
cleanups.
Specifics:
- Update qcom-hw DT bindings to include Eliza hardware (Abel Vesa)
- Update cpufreq-dt-platdev blocklist (Faruque Ansari)
- Minor updates to driver and dt-bindings for Tegra (Thierry Reding,
Rosen Penev)
- Add MAINTAINERS entry for CPPC driver (Viresh Kumar)
- Add support for new features: CPPC performance priority, Dynamic
EPP, Raw EPP, and new unit tests for them to amd-pstate (Gautham
Shenoy, Mario Limonciello)
- Fix sysfs files being present when HW missing and broken/outdated
documentation in the amd-pstate driver (Ninad Naik, Gautham Shenoy)
- Pass the policy to cpufreq_driver->adjust_perf() to avoid using
cpufreq_cpu_get() in the .adjust_perf() callback in amd-pstate
which leads to a scheduling-while-atomic bug (K Prateek Nayak)
- Clean up dead code in Kconfig for cpufreq (Julian Braha)
- Remove max_freq_req update for pre-existing cpufreq policy and add
a boost_freq_req QoS request to save the boost constraint instead
of overwriting the last scaling_max_freq constraint (Pierre
Gondois)
- Embed cpufreq QoS freq_req objects in cpufreq policy so they all
are allocated in one go along with the policy to simplify lifetime
rules and avoid error handling issues (Viresh Kumar)
- Use DMI max speed when CPPC is unavailable in the acpi-cpufreq
scaling driver (Henry Tseng)
- Switch policy_is_shared() in cpufreq to using cpumask_nth() instead
of cpumask_weight() because the former is more efficient (Yury
Norov)
- Use sysfs_emit() in sysfs show functions for cpufreq governor
attributes (Thorsten Blum)
- Update intel_pstate to stop returning an error when "off" is
written to its status sysfs attribute while the driver is already
off (Fabio De Francesco)
- Include current frequency in the debug message printed by
__cpufreq_driver_target() (Pengjie Zhang)
- Refine stopped tick handling in the menu cpuidle governor and
rearrange stopped tick handling in the teo cpuidle governor (Rafael
Wysocki)
- Add Panther Lake C-states table to the intel_idle driver (Artem
Bityutskiy)
- Clean up dead dependencies on CPU_IDLE in Kconfig (Julian Braha)
- Simplify cpuidle_register_device() with guard() (Huisong Li)
- Use performance level if available to distinguish between rates in
OPP debugfs (Manivannan Sadhasivam)
- Fix scoped_guard in dev_pm_opp_xlate_required_opp() (Viresh Kumar)
- Return -ENODATA if the snapshot image is not loaded (Alberto
Garcia)
- Remove inclusion of crypto/hash.h from hibernate_64.c on x86 (Eric
Biggers)
- Clean up and rearrange the intel_rapl power capping driver to make
the respective interface drivers (TPMI, MSR, and MMOI) hold their
own settings and primitives and consolidate PL4 and PMU support
flags into rapl_defaults (Kuppuswamy Sathyanarayanan)
- Correct kernel-doc function parameter names in the power capping
core code (Randy Dunlap)
- Remove unneeded casting for HZ_PER_KHZ in devfreq (Andy Shevchenko)
- Use _visible attribute to replace create/remove_sysfs_files() in
devfreq (Pengjie Zhang)
- Add Tegra114 support to activity monitor device in tegra30-devfreq
as a preparation to upcoming EMC controller support (Svyatoslav
Ryhel)
- Fix mistakes in cpupower man pages, add the boost and epp options
to the cpupower-frequency-info man page, and add the perf-bias
option to the cpupower-info man page (Roberto Ricci)
- Remove unnecessary extern declarations from getopt.h in arguments
parsing functions in cpufreq-set, cpuidle-info, cpuidle-set,
cpupower-info, and cpupower-set utilities (Kaushlendra Kumar)"
* tag 'pm-7.1-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm: (74 commits)
cpufreq/amd-pstate: Add POWER_SUPPLY select for dynamic EPP
cpupower: remove extern declarations in cmd functions
cpuidle: Simplify cpuidle_register_device() with guard()
PM / devfreq: tegra30-devfreq: add support for Tegra114
PM / devfreq: use _visible attribute to replace create/remove_sysfs_files()
PM / devfreq: Remove unneeded casting for HZ_PER_KHZ
MAINTAINERS: amd-pstate: Step down as maintainer, add Prateek as reviewer
cpufreq: Pass the policy to cpufreq_driver->adjust_perf()
cpufreq/amd-pstate: Pass the policy to amd_pstate_update()
cpufreq/amd-pstate-ut: Add a unit test for raw EPP
cpufreq/amd-pstate: Add support for raw EPP writes
cpufreq/amd-pstate: Add support for platform profile class
cpufreq/amd-pstate: add kernel command line to override dynamic epp
cpufreq/amd-pstate: Add dynamic energy performance preference
Documentation: amd-pstate: fix dead links in the reference section
cpufreq/amd-pstate: Cache the max frequency in cpudata
Documentation/amd-pstate: Add documentation for amd_pstate_floor_{freq,count}
Documentation/amd-pstate: List amd_pstate_prefcore_ranking sysfs file
Documentation/amd-pstate: List amd_pstate_hw_prefcore sysfs file
amd-pstate-ut: Add a testcase to validate the visibility of driver attributes
...
- debugfs:
- Fix NULL pointer dereference in debugfs_create_str()
- Fix misplaced EXPORT_SYMBOL_GPL for debugfs_create_str()
- Fix soundwire debugfs NULL pointer dereference from uninitialized
firmware_file
- device property:
- Make fwnode flags modifications thread safe; widen the field to
unsigned long and use set_bit() / clear_bit() based accessors
- Document how to check for the property presence
- devres:
- Separate struct devres_node from its "subclasses" (struct devres,
struct devres_group); give struct devres_node its own release and
free callbacks for per-type dispatch
- Introduce struct devres_action for devres actions, avoiding the
ARCH_DMA_MINALIGN alignment overhead of struct devres
- Export struct devres_node and its init/add/remove/dbginfo
primitives for use by Rust Devres<T>
- Fix missing node debug info in devm_krealloc()
- Use guard(spinlock_irqsave) where applicable; consolidate unlock
paths in devres_release_group()
- driver_override:
- Convert PCI, WMI, vdpa, s390/cio, s390/ap, and fsl-mc to the
generic driver_override infrastructure, replacing per-bus
driver_override strings, sysfs attributes, and match logic; fixes
a potential UAF from unsynchronized access to driver_override in
bus match() callbacks
- Simplify __device_set_driver_override() logic
- kernfs:
- Send IN_DELETE_SELF and IN_IGNORED inotify events on kernfs
file and directory removal
- Add corresponding selftests for memcg
- platform:
- Allow attaching software nodes when creating platform devices via
a new 'swnode' field in struct platform_device_info
- Add kerneldoc for struct platform_device_info
- software node:
- Move software node initialization from postcore_initcall() to
driver_init(), making it available early in the boot process
- Move kernel_kobj initialization (ksysfs_init) earlier to support
the above
- Remove software_node_exit(); dead code in a built-in unit
- SoC:
- Introduce of_machine_read_compatible() and of_machine_read_model()
OF helpers and export soc_attr_read_machine() to replace direct
accesses to of_root from SoC drivers; also enables
CONFIG_COMPILE_TEST coverage for these drivers
- sysfs:
- Constify attribute group array pointers to
'const struct attribute_group *const *' in sysfs functions,
device_add_groups() / device_remove_groups(), and struct class
- Rust:
- Devres:
- Embed struct devres_node directly in Devres<T> instead of going
through devm_add_action(), avoiding the extra allocation and
the unnecessary ARCH_DMA_MINALIGN alignment
- I/O:
- Turn IoCapable from a marker trait into a functional trait
carrying the raw I/O accessor implementation (io_read /
io_write), providing working defaults for the per-type Io
methods
- Add RelaxedMmio wrapper type, making relaxed accessors usable
in code generic over the Io trait
- Remove overloaded per-type Io methods and per-backend macros
from Mmio and PCI ConfigSpace
- I/O (Register):
- Add IoLoc trait and generic read/write/update methods to the Io
trait, making I/O operations parameterizable by typed locations
- Add register! macro for defining hardware register types with
typed bitfield accessors backed by Bounded values; supports
direct, relative, and array register addressing
- Add write_reg() / try_write_reg() and LocatedRegister trait
- Update PCI sample driver to demonstrate the register! macro
Example:
```
register! {
/// UART control register.
CTRL(u32) @ 0x18 {
/// Receiver enable.
19:19 rx_enable => bool;
/// Parity configuration.
14:13 parity ?=> Parity;
}
/// FIFO watermark and counter register.
WATER(u32) @ 0x2c {
/// Number of datawords in the receive FIFO.
26:24 rx_count;
/// RX interrupt threshold.
17:16 rx_water;
}
}
impl WATER {
fn rx_above_watermark(&self) -> bool {
self.rx_count() > self.rx_water()
}
}
fn init(bar: &pci::Bar<BAR0_SIZE>) {
let water = WATER::zeroed()
.with_const_rx_water::<1>(); // > 3 would not compile
bar.write_reg(water);
let ctrl = CTRL::zeroed()
.with_parity(Parity::Even)
.with_rx_enable(true);
bar.write_reg(ctrl);
}
fn handle_rx(bar: &pci::Bar<BAR0_SIZE>) {
if bar.read(WATER).rx_above_watermark() {
// drain the FIFO
}
}
fn set_parity(bar: &pci::Bar<BAR0_SIZE>, parity: Parity) {
bar.update(CTRL, |r| r.with_parity(parity));
}
```
- IRQ:
- Move 'static bounds from where clauses to trait declarations
for IRQ handler traits
- Misc:
- Enable the generic_arg_infer Rust feature
- Extend Bounded with shift operations, single-bit bool conversion,
and const get()
- Misc:
- Make deferred_probe_timeout default a Kconfig option
- Drop auxiliary_dev_pm_ops; the PM core falls back to driver PM
callbacks when no bus type PM ops are set
- Add conditional guard support for device_lock()
- Add ksysfs.c to the DRIVER CORE MAINTAINERS entry
- Fix kernel-doc warnings in base.h
- Fix stale reference to memory_block_add_nid() in documentation
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Merge tag 'driver-core-7.1-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/driver-core/driver-core
Pull driver core updates from Danilo Krummrich:
"debugfs:
- Fix NULL pointer dereference in debugfs_create_str()
- Fix misplaced EXPORT_SYMBOL_GPL for debugfs_create_str()
- Fix soundwire debugfs NULL pointer dereference from uninitialized
firmware_file
device property:
- Make fwnode flags modifications thread safe; widen the field to
unsigned long and use set_bit() / clear_bit() based accessors
- Document how to check for the property presence
devres:
- Separate struct devres_node from its "subclasses" (struct devres,
struct devres_group); give struct devres_node its own release and
free callbacks for per-type dispatch
- Introduce struct devres_action for devres actions, avoiding the
ARCH_DMA_MINALIGN alignment overhead of struct devres
- Export struct devres_node and its init/add/remove/dbginfo
primitives for use by Rust Devres<T>
- Fix missing node debug info in devm_krealloc()
- Use guard(spinlock_irqsave) where applicable; consolidate unlock
paths in devres_release_group()
driver_override:
- Convert PCI, WMI, vdpa, s390/cio, s390/ap, and fsl-mc to the
generic driver_override infrastructure, replacing per-bus
driver_override strings, sysfs attributes, and match logic; fixes a
potential UAF from unsynchronized access to driver_override in bus
match() callbacks
- Simplify __device_set_driver_override() logic
kernfs:
- Send IN_DELETE_SELF and IN_IGNORED inotify events on kernfs file
and directory removal
- Add corresponding selftests for memcg
platform:
- Allow attaching software nodes when creating platform devices via a
new 'swnode' field in struct platform_device_info
- Add kerneldoc for struct platform_device_info
software node:
- Move software node initialization from postcore_initcall() to
driver_init(), making it available early in the boot process
- Move kernel_kobj initialization (ksysfs_init) earlier to support
the above
- Remove software_node_exit(); dead code in a built-in unit
SoC:
- Introduce of_machine_read_compatible() and of_machine_read_model()
OF helpers and export soc_attr_read_machine() to replace direct
accesses to of_root from SoC drivers; also enables
CONFIG_COMPILE_TEST coverage for these drivers
sysfs:
- Constify attribute group array pointers to
'const struct attribute_group *const *' in sysfs functions,
device_add_groups() / device_remove_groups(), and struct class
Rust:
- Devres:
- Embed struct devres_node directly in Devres<T> instead of going
through devm_add_action(), avoiding the extra allocation and the
unnecessary ARCH_DMA_MINALIGN alignment
- I/O:
- Turn IoCapable from a marker trait into a functional trait
carrying the raw I/O accessor implementation (io_read /
io_write), providing working defaults for the per-type Io
methods
- Add RelaxedMmio wrapper type, making relaxed accessors usable in
code generic over the Io trait
- Remove overloaded per-type Io methods and per-backend macros
from Mmio and PCI ConfigSpace
- I/O (Register):
- Add IoLoc trait and generic read/write/update methods to the Io
trait, making I/O operations parameterizable by typed locations
- Add register! macro for defining hardware register types with
typed bitfield accessors backed by Bounded values; supports
direct, relative, and array register addressing
- Add write_reg() / try_write_reg() and LocatedRegister trait
- Update PCI sample driver to demonstrate the register! macro
Example:
```
register! {
/// UART control register.
CTRL(u32) @ 0x18 {
/// Receiver enable.
19:19 rx_enable => bool;
/// Parity configuration.
14:13 parity ?=> Parity;
}
/// FIFO watermark and counter register.
WATER(u32) @ 0x2c {
/// Number of datawords in the receive FIFO.
26:24 rx_count;
/// RX interrupt threshold.
17:16 rx_water;
}
}
impl WATER {
fn rx_above_watermark(&self) -> bool {
self.rx_count() > self.rx_water()
}
}
fn init(bar: &pci::Bar<BAR0_SIZE>) {
let water = WATER::zeroed()
.with_const_rx_water::<1>(); // > 3 would not compile
bar.write_reg(water);
let ctrl = CTRL::zeroed()
.with_parity(Parity::Even)
.with_rx_enable(true);
bar.write_reg(ctrl);
}
fn handle_rx(bar: &pci::Bar<BAR0_SIZE>) {
if bar.read(WATER).rx_above_watermark() {
// drain the FIFO
}
}
fn set_parity(bar: &pci::Bar<BAR0_SIZE>, parity: Parity) {
bar.update(CTRL, |r| r.with_parity(parity));
}
```
- IRQ:
- Move 'static bounds from where clauses to trait declarations for
IRQ handler traits
- Misc:
- Enable the generic_arg_infer Rust feature
- Extend Bounded with shift operations, single-bit bool
conversion, and const get()
Misc:
- Make deferred_probe_timeout default a Kconfig option
- Drop auxiliary_dev_pm_ops; the PM core falls back to driver PM
callbacks when no bus type PM ops are set
- Add conditional guard support for device_lock()
- Add ksysfs.c to the DRIVER CORE MAINTAINERS entry
- Fix kernel-doc warnings in base.h
- Fix stale reference to memory_block_add_nid() in documentation"
* tag 'driver-core-7.1-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/driver-core/driver-core: (67 commits)
bus: fsl-mc: use generic driver_override infrastructure
s390/ap: use generic driver_override infrastructure
s390/cio: use generic driver_override infrastructure
vdpa: use generic driver_override infrastructure
platform/wmi: use generic driver_override infrastructure
PCI: use generic driver_override infrastructure
driver core: make software nodes available earlier
software node: remove software_node_exit()
kernel: ksysfs: initialize kernel_kobj earlier
MAINTAINERS: add ksysfs.c to the DRIVER CORE entry
drivers/base/memory: fix stale reference to memory_block_add_nid()
device property: Document how to check for the property presence
soundwire: debugfs: initialize firmware_file to empty string
debugfs: fix placement of EXPORT_SYMBOL_GPL for debugfs_create_str()
debugfs: check for NULL pointer in debugfs_create_str()
driver core: Make deferred_probe_timeout default a Kconfig option
driver core: simplify __device_set_driver_override() clearing logic
driver core: auxiliary bus: Drop auxiliary_dev_pm_ops
device property: Make modifications of fwnode "flags" thread safe
rust: devres: embed struct devres_node directly
...
- randomize_kstack: Improve implementation across arches (Ryan Roberts)
- lkdtm/fortify: Drop unneeded FORTIFY_STR_OBJECT test
- refcount: Remove unused __signed_wrap function annotations
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Merge tag 'hardening-v7.1-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux
Pull hardening updates from Kees Cook:
- randomize_kstack: Improve implementation across arches (Ryan Roberts)
- lkdtm/fortify: Drop unneeded FORTIFY_STR_OBJECT test
- refcount: Remove unused __signed_wrap function annotations
* tag 'hardening-v7.1-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
lkdtm/fortify: Drop unneeded FORTIFY_STR_OBJECT test
refcount: Remove unused __signed_wrap function annotations
randomize_kstack: Unify random source across arches
randomize_kstack: Maintain kstack_offset per task
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Merge tag 'audit-pr-20260410' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/audit
Pull audit updates from Paul Moore:
- Improved handling of unknown status requests from userspace
The current kernel code ignores unknown/unused request bits sent from
userspace and returns an error code based on the results of the
request(s) it does understand. The patch from Ricardo fixes this so
that unknown requests return an -EINVAL to userspace, making
compatibility a bit easier moving forward.
- A number of small style and formatting cleanups
* tag 'audit-pr-20260410' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/audit:
audit: handle unknown status requests in audit_receive_msg()
audit: fix coding style issues
audit: remove redundant initialization of static variables to 0
audit: fix whitespace alignment in include/uapi/linux/audit.h
Please consider pulling these changes from the signed vfs-7.1-rc1.misc tag.
Thanks!
Christian
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Merge tag 'vfs-7.1-rc1.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs
Pull misc vfs updates from Christian Brauner:
"Features:
- coredump: add tracepoint for coredump events
- fs: hide file and bfile caches behind runtime const machinery
Fixes:
- fix architecture-specific compat_ftruncate64 implementations
- dcache: Limit the minimal number of bucket to two
- fs/omfs: reject s_sys_blocksize smaller than OMFS_DIR_START
- fs/mbcache: cancel shrink work before destroying the cache
- dcache: permit dynamic_dname()s up to NAME_MAX
Cleanups:
- remove or unexport unused fs_context infrastructure
- trivial ->setattr cleanups
- selftests/filesystems: Assume that TIOCGPTPEER is defined
- writeback: fix kernel-doc function name mismatch for wb_put_many()
- autofs: replace manual symlink buffer allocation in autofs_dir_symlink
- init/initramfs.c: trivial fix: FSM -> Finite-state machine
- fs: remove stale and duplicate forward declarations
- readdir: Introduce dirent_size()
- fs: Replace user_access_{begin/end} by scoped user access
- kernel: acct: fix duplicate word in comment
- fs: write a better comment in step_into() concerning .mnt assignment
- fs: attr: fix comment formatting and spelling issues"
* tag 'vfs-7.1-rc1.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: (28 commits)
dcache: permit dynamic_dname()s up to NAME_MAX
fs: attr: fix comment formatting and spelling issues
fs: hide file and bfile caches behind runtime const machinery
fs: write a better comment in step_into() concerning .mnt assignment
proc: rename proc_notify_change to proc_setattr
proc: rename proc_setattr to proc_nochmod_setattr
affs: rename affs_notify_change to affs_setattr
adfs: rename adfs_notify_change to adfs_setattr
hfs: update comments on hfs_inode_setattr
kernel: acct: fix duplicate word in comment
fs: Replace user_access_{begin/end} by scoped user access
readdir: Introduce dirent_size()
coredump: add tracepoint for coredump events
fs: remove do_sys_truncate
fs: pass on FTRUNCATE_* flags to do_truncate
fs: fix archiecture-specific compat_ftruncate64
fs: remove stale and duplicate forward declarations
init/initramfs.c: trivial fix: FSM -> Finite-state machine
autofs: replace manual symlink buffer allocation in autofs_dir_symlink
fs/mbcache: cancel shrink work before destroying the cache
...
Please consider pulling these changes from the signed vfs-7.1-rc1.pidfs tag.
Thanks!
Christian
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Merge tag 'vfs-7.1-rc1.pidfs' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs
Pull clone and pidfs updates from Christian Brauner:
"Add three new clone3() flags for pidfd-based process lifecycle
management.
CLONE_AUTOREAP:
CLONE_AUTOREAP makes a child process auto-reap on exit without ever
becoming a zombie. This is a per-process property in contrast to
the existing auto-reap mechanism via SA_NOCLDWAIT or SIG_IGN for
SIGCHLD which applies to all children of a given parent.
Currently the only way to automatically reap children is to set
SA_NOCLDWAIT or SIG_IGN on SIGCHLD. This is a parent-scoped
property affecting all children which makes it unsuitable for
libraries or applications that need selective auto-reaping of
specific children while still being able to wait() on others.
CLONE_AUTOREAP stores an autoreap flag in the child's
signal_struct. When the child exits do_notify_parent() checks this
flag and causes exit_notify() to transition the task directly to
EXIT_DEAD. Since the flag lives on the child it survives
reparenting: if the original parent exits and the child is
reparented to a subreaper or init the child still auto-reaps when
it eventually exits. This is cleaner than forcing the subreaper to
get SIGCHLD and then reaping it. If the parent doesn't care the
subreaper won't care. If there's a subreaper that would care it
would be easy enough to add a prctl() that either just turns back
on SIGCHLD and turns off auto-reaping or a prctl() that just
notifies the subreaper whenever a child is reparented to it.
CLONE_AUTOREAP can be combined with CLONE_PIDFD to allow the parent
to monitor the child's exit via poll() and retrieve exit status via
PIDFD_GET_INFO. Without CLONE_PIDFD it provides a fire-and-forget
pattern. No exit signal is delivered so exit_signal must be zero.
CLONE_THREAD and CLONE_PARENT are rejected: CLONE_THREAD because
autoreap is a process-level property, and CLONE_PARENT because an
autoreap child reparented via CLONE_PARENT could become an
invisible zombie under a parent that never calls wait().
The flag is not inherited by the autoreap process's own children.
Each child that should be autoreaped must be explicitly created
with CLONE_AUTOREAP.
CLONE_NNP:
CLONE_NNP sets no_new_privs on the child at clone time. Unlike
prctl(PR_SET_NO_NEW_PRIVS) which a process sets on itself,
CLONE_NNP allows the parent to impose no_new_privs on the child at
creation without affecting the parent's own privileges.
CLONE_THREAD is rejected because threads share credentials.
CLONE_NNP is useful on its own for any spawn-and-sandbox pattern
but was specifically introduced to enable unprivileged usage of
CLONE_PIDFD_AUTOKILL.
CLONE_PIDFD_AUTOKILL:
This flag ties a child's lifetime to the pidfd returned from
clone3(). When the last reference to the struct file created by
clone3() is closed the kernel sends SIGKILL to the child. A pidfd
obtained via pidfd_open() for the same process does not keep the
child alive and does not trigger autokill - only the specific
struct file from clone3() has this property. This is useful for
container runtimes, service managers, and sandboxed subprocess
execution - any scenario where the child must die if the parent
crashes or abandons the pidfd or just wants a throwaway helper
process.
CLONE_PIDFD_AUTOKILL requires both CLONE_PIDFD and CLONE_AUTOREAP.
It requires CLONE_PIDFD because the whole point is tying the
child's lifetime to the pidfd. It requires CLONE_AUTOREAP because a
killed child with no one to reap it would become a zombie - the
primary use case is the parent crashing or abandoning the pidfd so
no one is around to call waitpid(). CLONE_THREAD is rejected
because autokill targets a process not a thread.
If CLONE_NNP is specified together with CLONE_PIDFD_AUTOKILL an
unprivileged user may spawn a process that is autokilled. The child
cannot escalate privileges via setuid/setgid exec after being
spawned. If CLONE_PIDFD_AUTOKILL is specified without CLONE_NNP the
caller must have have CAP_SYS_ADMIN in its user namespace"
* tag 'vfs-7.1-rc1.pidfs' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
selftests: check pidfd_info->coredump_code correctness
pidfds: add coredump_code field to pidfd_info
kselftest/coredump: reintroduce null pointer dereference
selftests/pidfd: add CLONE_PIDFD_AUTOKILL tests
selftests/pidfd: add CLONE_NNP tests
selftests/pidfd: add CLONE_AUTOREAP tests
pidfd: add CLONE_PIDFD_AUTOKILL
clone: add CLONE_NNP
clone: add CLONE_AUTOREAP
Please consider pulling these changes from the signed namespaces-7.1-rc1.misc tag.
Thanks!
Christian
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Merge tag 'namespaces-7.1-rc1.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs
Pull namespace update from Christian Brauner:
"Add two simple helper macros for the namespace infrastructure"
* tag 'namespaces-7.1-rc1.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
nsproxy: Add FOR_EACH_NS_TYPE() X-macro and CLONE_NS_ALL
Please consider pulling these changes from the signed vfs-7.1-rc1.kino tag.
Thanks!
Christian
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Merge tag 'vfs-7.1-rc1.kino' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs
Pull vfs i_ino updates from Christian Brauner:
"For historical reasons, the inode->i_ino field is an unsigned long,
which means that it's 32 bits on 32 bit architectures. This has caused
a number of filesystems to implement hacks to hash a 64-bit identifier
into a 32-bit field, and deprives us of a universal identifier field
for an inode.
This changes the inode->i_ino field from an unsigned long to a u64.
This shouldn't make any material difference on 64-bit hosts, but
32-bit hosts will see struct inode grow by at least 4 bytes. This
could have effects on slabcache sizes and field alignment.
The bulk of the changes are to format strings and tracepoints, since
the kernel itself doesn't care that much about the i_ino field. The
first patch changes some vfs function arguments, so check that one out
carefully.
With this change, we may be able to shrink some inode structures. For
instance, struct nfs_inode has a fileid field that holds the 64-bit
inode number. With this set of changes, that field could be
eliminated. I'd rather leave that sort of cleanups for later just to
keep this simple"
* tag 'vfs-7.1-rc1.kino' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
nilfs2: fix 64-bit division operations in nilfs_bmap_find_target_in_group()
EVM: add comment describing why ino field is still unsigned long
vfs: remove externs from fs.h on functions modified by i_ino widening
treewide: fix missed i_ino format specifier conversions
ext4: fix signed format specifier in ext4_load_inode trace event
treewide: change inode->i_ino from unsigned long to u64
nilfs2: widen trace event i_ino fields to u64
f2fs: widen trace event i_ino fields to u64
ext4: widen trace event i_ino fields to u64
zonefs: widen trace event i_ino fields to u64
hugetlbfs: widen trace event i_ino fields to u64
ext2: widen trace event i_ino fields to u64
cachefiles: widen trace event i_ino fields to u64
vfs: widen trace event i_ino fields to u64
net: change sock.sk_ino and sock_i_ino() to u64
audit: widen ino fields to u64
vfs: widen inode hash/lookup functions to u64
NOCB CPU management:
- Consolidate rcu_nocb_cpu_offload() and rcu_nocb_cpu_deoffload() to reduce
code duplication.
- Extract nocb_bypass_needs_flush() helper to reduce duplication in NOCB
bypass path.
rcutorture/torture infrastructure:
- Add NOCB01 config for RCU_LAZY torture testing.
- Add NOCB02 config for NOCB poll mode testing.
- Add TRIVIAL-PREEMPT config for textbook-style preemptible RCU torture.
- Test call_srcu() with preemption both disabled and enabled.
- Remove kvm-check-branches.sh in favor of kvm-series.sh.
- Make hangs more visible in torture.sh output.
- Add informative message for tests without a recheck file.
- Fix numeric test comparison in srcu_lockdep.sh.
- Use torture_shutdown_init() in refscale and rcuscale instead of open-coded
shutdown functions.
- Fix modulo-zero error in torture_hrtimeout_ns().
SRCU:
- Fix SRCU read flavor macro comments.
- Fix s/they disables/they disable/ typo in srcu_read_unlock_fast().
RCU Tasks:
- Document that RCU Tasks Trace grace periods now imply RCU grace periods.
- Remove unnecessary smp_store_release() in cblist_init_generic().
RCU stall:
- Add BOOTPARAM_RCU_STALL_PANIC Kconfig option to allow triggering a kernel
panic on RCU stall via kernel boot parameter.
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Merge tag 'rcu.2026.03.31a' of git://git.kernel.org/pub/scm/linux/kernel/git/rcu/linux
Pull RCU updates from Joel Fernandes:
"NOCB CPU management:
- Consolidate rcu_nocb_cpu_offload() and rcu_nocb_cpu_deoffload() to
reduce code duplication
- Extract nocb_bypass_needs_flush() helper to reduce duplication in
NOCB bypass path
rcutorture/torture infrastructure:
- Add NOCB01 config for RCU_LAZY torture testing
- Add NOCB02 config for NOCB poll mode testing
- Add TRIVIAL-PREEMPT config for textbook-style preemptible RCU
torture
- Test call_srcu() with preemption both disabled and enabled
- Remove kvm-check-branches.sh in favor of kvm-series.sh
- Make hangs more visible in torture.sh output
- Add informative message for tests without a recheck file
- Fix numeric test comparison in srcu_lockdep.sh
- Use torture_shutdown_init() in refscale and rcuscale instead of
open-coded shutdown functions
- Fix modulo-zero error in torture_hrtimeout_ns().
SRCU:
- Fix SRCU read flavor macro comments
- Fix s/they disables/they disable/ typo in srcu_read_unlock_fast()
RCU Tasks:
- Document that RCU Tasks Trace grace periods now imply RCU grace
periods
- Remove unnecessary smp_store_release() in cblist_init_generic()"
* tag 'rcu.2026.03.31a' of git://git.kernel.org/pub/scm/linux/kernel/git/rcu/linux:
rcutorture: Test call_srcu() with preemption disabled and not
rcu: Add BOOTPARAM_RCU_STALL_PANIC Kconfig option
torture: Avoid modulo-zero error in torture_hrtimeout_ns()
rcu/nocb: Extract nocb_bypass_needs_flush() to reduce duplication
rcu/nocb: Consolidate rcu_nocb_cpu_offload/deoffload functions
rcu-tasks: Remove unnecessary smp_store_release() in cblist_init_generic()
rcutorture: Add NOCB02 config for nocb poll mode testing
rcutorture: Add NOCB01 config for RCU_LAZY torture testing
rcu-tasks: Document that RCU Tasks Trace grace periods now imply RCU grace periods
srcu: Fix s/they disables/they disable/ typo in srcu_read_unlock_fast()
srcu: Fix SRCU read flavor macro comments
rcuscale: Ditch rcu_scale_shutdown in favor of torture_shutdown_init()
refscale: Ditch ref_scale_shutdown in favor of torture_shutdown_init()
rcutorture: Fix numeric "test" comparison in srcu_lockdep.sh
torture: Print informative message for test without recheck file
torture: Make hangs more visible in torture.sh output
kvm-check-branches.sh: Remove in favor of kvm-series.sh
rcutorture: Add a textbook-style trivial preemptible RCU
On uniprocessor (UP) configs such as nios2, NR_CPUS is 1, so
cpu_shard_id[] is a single-element array (int[1]). In
llc_populate_cpu_shard_id(), cpumask_first(sibling_cpus) returns an
unsigned int that the compiler cannot prove is always 0, triggering
a -Warray-bounds warning when the result is used to index
cpu_shard_id[]:
kernel/workqueue.c:8321:55: warning: array subscript 1 is above
array bounds of 'int[1]' [-Warray-bounds]
8321 | cpu_shard_id[c] = cpu_shard_id[cpumask_first(sibling_cpus)];
| ~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
This is a false positive: sibling_cpus can never be empty here because
'c' itself is always set in it, so cpumask_first() will always return a
valid CPU. However, the compiler cannot prove this statically, and the
warning only manifests on UP configs where the array size is 1.
Add a bounds check with WARN_ON_ONCE to silence the warning, and store
the result in a local variable to make the code clearer and avoid calling
cpumask_first() twice.
Fixes: 5920d046f7 ("workqueue: add WQ_AFFN_CACHE_SHARD affinity scope")
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202604022343.GQtkF2vO-lkp@intel.com/
Signed-off-by: Breno Leitao <leitao@debian.org>
Signed-off-by: Tejun Heo <tj@kernel.org>
* New features:
- Add support for tracing in the standalone EL2 hypervisor code,
which should help both debugging and performance analysis.
This comes with a full infrastructure for 'remote' trace buffers
that can be exposed by non-kernel entities such as firmware.
- Add support for GICv5 Per Processor Interrupts (PPIs), as the
starting point for supporting the new GIC architecture in KVM.
- Finally add support for pKVM protected guests, with anonymous
memory being used as a backing store. About time!
* Improvements and bug fixes:
- Rework the dreaded user_mem_abort() function to make it more
maintainable, reducing the amount of state being exposed to
the various helpers and rendering a substantial amount of
state immutable.
- Expand the Stage-2 page table dumper to support NV shadow
page tables on a per-VM basis.
- Tidy up the pKVM PSCI proxy code to be slightly less hard
to follow.
- Fix both SPE and TRBE in non-VHE configurations so that they
do not generate spurious, out of context table walks that
ultimately lead to very bad HW lockups.
- A small set of patches fixing the Stage-2 MMU freeing in error
cases.
- Tighten-up accepted SMC immediate value to be only #0 for host
SMCCC calls.
- The usual cleanups and other selftest churn.
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Merge tag 'kvmarm-7.1' of git://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm into HEAD
KVM/arm64 updates for 7.1
* New features:
- Add support for tracing in the standalone EL2 hypervisor code,
which should help both debugging and performance analysis.
This comes with a full infrastructure for 'remote' trace buffers
that can be exposed by non-kernel entities such as firmware.
- Add support for GICv5 Per Processor Interrupts (PPIs), as the
starting point for supporting the new GIC architecture in KVM.
- Finally add support for pKVM protected guests, with anonymous
memory being used as a backing store. About time!
* Improvements and bug fixes:
- Rework the dreaded user_mem_abort() function to make it more
maintainable, reducing the amount of state being exposed to
the various helpers and rendering a substantial amount of
state immutable.
- Expand the Stage-2 page table dumper to support NV shadow
page tables on a per-VM basis.
- Tidy up the pKVM PSCI proxy code to be slightly less hard
to follow.
- Fix both SPE and TRBE in non-VHE configurations so that they
do not generate spurious, out of context table walks that
ultimately lead to very bad HW lockups.
- A small set of patches fixing the Stage-2 MMU freeing in error
cases.
- Tighten-up accepted SMC immediate value to be only #0 for host
SMCCC calls.
- The usual cleanups and other selftest churn.
xulang <xulang@uniontech.com> says:
====================
Fix OOB read when copying element from a BPF_MAP_TYPE_CGROUP_STORAGE
map to another pcpu map with the same value_size that is not rounded
up to 8 bytes, and add a test case to reproduce the issue.
The root cause is that pcpu_init_value() uses copy_map_value_long() which
rounds up the copy size to 8 bytes, but CGROUP_STORAGE map values are not
8-byte aligned (e.g., 4-byte). This causes a 4-byte OOB read when
the copy is performed.
====================
Link: https://lore.kernel.org/r/7653EEEC2BAB17DF+20260402073948.2185396-1-xulang@uniontech.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
An out-of-bounds read occurs when copying element from a
BPF_MAP_TYPE_CGROUP_STORAGE map to another pcpu map with the
same value_size that is not rounded up to 8 bytes.
The issue happens when:
1. A CGROUP_STORAGE map is created with value_size not aligned to
8 bytes (e.g., 4 bytes)
2. A pcpu map is created with the same value_size (e.g., 4 bytes)
3. Update element in 2 with data in 1
pcpu_init_value assumes that all sources are rounded up to 8 bytes,
and invokes copy_map_value_long to make a data copy, However, the
assumption doesn't stand since there are some cases where the source
may not be rounded up to 8 bytes, e.g., CGROUP_STORAGE, skb->data.
the verifier verifies exactly the size that the source claims, not
the size rounded up to 8 bytes by kernel, an OOB happens when the
source has only 4 bytes while the copy size(4) is rounded up to 8.
Fixes: d3bec0138b ("bpf: Zero-fill re-used per-cpu map element")
Reported-by: Kaiyan Mei <kaiyanm@hust.edu.cn>
Closes: https://lore.kernel.org/all/14e6c70c.6c121.19c0399d948.Coremail.kaiyanm@hust.edu.cn/
Link: https://lore.kernel.org/r/420FEEDDC768A4BE+20260402074236.2187154-1-xulang@uniontech.com
Signed-off-by: Lang Xu <xulang@uniontech.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
The compiler sometimes stores the result of a PTR_TO_ARENA and SCALAR
operation into the scalar register rather than the pointer register.
Relax the verifier to allow operations between a source arena register
and a destination non-arena register, marking the destination's value
as a PTR_TO_ARENA.
Signed-off-by: Emil Tsalapatis <emil@etsalapatis.com>
Acked-by: Song Liu <song@kernel.org>
Fixes: 6082b6c328 ("bpf: Recognize addr_space_cast instruction in the verifier.")
Link: https://lore.kernel.org/r/20260412174546.18684-2-emil@etsalapatis.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
The fsession attach type is missed in the verifier log in
check_get_func_ip(), bpf_check_attach_target() and check_attach_btf_id().
Update them to make the verifier log proper. Meanwhile, update the
corresponding selftests.
Acked-by: Leon Hwang <leon.hwang@linux.dev>
Signed-off-by: Menglong Dong <dongml2@chinatelecom.cn>
Link: https://lore.kernel.org/r/20260412060346.142007-2-dongml2@chinatelecom.cn
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
BTF validation logic is independent from the main verifier.
Move it into check_btf.c
Acked-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/r/20260412152936.54262-7-alexei.starovoitov@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
verifier.c is huge. Move is_state_visited() to states.c,
so that all state equivalence logic is in one file.
Mechanical move. No functional changes.
Acked-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/r/20260412152936.54262-5-alexei.starovoitov@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
verifier.c is huge. Split fixup/post-processing logic that runs after
the verifier accepted the program into fixups.c.
Mechanical move. No functional changes.
Acked-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/r/20260412152936.54262-2-alexei.starovoitov@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
- Fix incomplete activation of multiple inactive works when unplugging a
pool_workqueue, where the pending_pwqs list wasn't being updated for
subsequent works.
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Merge tag 'wq-for-7.0-rc7-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq
Pull workqueue fix from Tejun Heo:
"This is a fix for a stall which triggers on ordered workqueues when
there are multiple inactive work items during workqueue property
changes through sysfs, which doesn't happen that frequently.
While really late, the fix is very low risk as it just repeats an
operation which is already being performed:
- Fix incomplete activation of multiple inactive works when
unplugging a pool_workqueue, where the pending_pwqs list
wasn't being updated for subsequent works"
* tag 'wq-for-7.0-rc7-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq:
workqueue: Add pool_workqueue to pending_pwqs list when unplugging multiple inactive works
- Invert the inverted fastpath decision in check_tick_dependency(), which
prevents NOHZ full to stop the tick. That's a regression introduced in
the 7.0 merge window.
- Prevent a unpriviledged DoS in the clockevents code, where user space
can starve the timer interrupt by arming a timerfd or posix interval
timer in a tight loop with an absolute expiry time in the past. The
fix turned out to be incomplete and was was amended yesterday to make
it work on some 20 years old AMD machines as well. All issues with it
have been confirmed to be resolved by various reporters.
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Merge tag 'timers-urgent-2026-04-12' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull timer fixes from Thomas Gleixner:
"Two fixes for the time/timers subsystem:
- Invert the inverted fastpath decision in check_tick_dependency(),
which prevents NOHZ full to stop the tick. That's a regression
introduced in the 7.0 merge window.
- Prevent a unpriviledged DoS in the clockevents code, where user
space can starve the timer interrupt by arming a timerfd or posix
interval timer in a tight loop with an absolute expiry time in the
past. The fix turned out to be incomplete and was was amended
yesterday to make it work on some 20 years old AMD machines as
well. All issues with it have been confirmed to be resolved by
various reporters"
* tag 'timers-urgent-2026-04-12' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
clockevents: Prevent timer interrupt starvation
tick/nohz: Fix inverted return value in check_tick_dependency() fast path
- tracing/probe: reject non-closed empty immediate strings
Fixed a buffer index underflow bug that occurred when passing an
non-closed empty immediate string to the probe event.
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Merge tag 'probes-fixes-v7.0-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace
Pull tracing probe fix from Masami Hiramatsu:
"Reject non-closed empty immediate strings
Fix a buffer index underflow bug that occurred when passing an
non-closed empty immediate string to the probe event"
* tag 'probes-fixes-v7.0-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
tracing/probe: reject non-closed empty immediate strings
Remove the check that rejects sleepable BPF programs from doing
BPF_ANY/BPF_EXIST updates on local storage. This restriction was added
in commit b00fa38a9c ("bpf: Enable non-atomic allocations in local
storage") because kzalloc(GFP_KERNEL) could sleep inside
local_storage->lock. This is no longer a concern: all local storage
allocations now use kmalloc_nolock() which never sleeps.
In addition, since kmalloc_nolock() only accepts __GFP_ACCOUNT,
__GFP_ZERO and __GFP_NO_OBJ_EXT, the gfp_flags parameter plumbing from
bpf_*_storage_get() to bpf_local_storage_update() becomes dead code.
Remove gfp_flags from bpf_selem_alloc(), bpf_local_storage_alloc() and
bpf_local_storage_update(). Drop the hidden 5th argument from
bpf_*_storage_get helpers, and remove the verifier patching that
injected GFP_KERNEL/GFP_ATOMIC into the fifth argument.
Signed-off-by: Amery Hung <ameryhung@gmail.com>
Link: https://lore.kernel.org/r/20260411015419.114016-4-ameryhung@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Switch to kmalloc_nolock() universally in local storage. Socket local
storage didn't move to kmalloc_nolock() when BPF memory allocator was
replaced by it for performance reasons. Now that kfree_rcu() supports
freeing memory allocated by kmalloc_nolock(), we can move the remaining
local storages to use kmalloc_nolock() and cleanup the cluttered free
paths.
Use kfree() instead of kfree_nolock() in bpf_selem_free_trace_rcu() and
bpf_local_storage_free_trace_rcu(). Both callbacks run in process context
where spinning is allowed, so kfree_nolock() is unnecessary.
Benchmark:
./bench -p 1 local-storage-create --storage-type socket \
--batch-size {16,32,64}
The benchmark is a microbenchmark stress-testing how fast local storage
can be created. There is no measurable throughput change for socket local
storage after switching from kzalloc() to kmalloc_nolock().
Socket local storage
batch creation speed diff
--------------- ---- ------------------ ----
Baseline 16 433.9 ± 0.6 k/s
32 434.3 ± 1.4 k/s
64 434.2 ± 0.7 k/s
After 16 439.0 ± 1.9 k/s +1.2%
32 437.3 ± 2.0 k/s +0.7%
64 435.8 ± 2.5k/s +0.4%
Also worth noting that the baseline got a 5% throughput boost when sheaf
replaces percpu partial slab recently [0].
[0] https://lore.kernel.org/bpf/20260123-sheaves-for-all-v4-0-041323d506f7@suse.cz/
Signed-off-by: Amery Hung <ameryhung@gmail.com>
Link: https://lore.kernel.org/r/20260411015419.114016-3-ameryhung@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
kick_cpus_irq_workfn() warns when scx_kick_syncs is NULL, but this can
legitimately happen when a BPF timer or other kick source races with
free_kick_syncs() during scheduler disable. Drop the pr_warn_once() and
add a comment explaining the race.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Zhao Mengmeng <zhaomengmeng@kylinos.cn>
When regsafe() compares two scalar registers that both carry
BPF_ADD_CONST, check_scalar_ids() maps their full compound id
(aka base | BPF_ADD_CONST flag) as one idmap entry. However,
it never verifies that the underlying base ids, that is, with
the flag stripped are consistent with existing idmap mappings.
This allows construction of two verifier states where the old
state has R3 = R2 + 10 (both sharing base id A) while the current
state has R3 = R4 + 10 (base id C, unrelated to R2). The idmap
creates two independent entries: A->B (for R2) and A|flag->C|flag
(for R3), without catching that A->C conflicts with A->B. State
pruning then incorrectly succeeds.
Fix this by additionally verifying base ID mapping consistency
whenever BPF_ADD_CONST is set: after mapping the compound ids,
also invoke check_ids() on the base IDs (flag bits stripped).
This ensures that if A was already mapped to B from comparing
the source register, any ADD_CONST derivative must also derive
from B, not an unrelated C.
Fixes: 98d7ca374b ("bpf: Track delta between "linked" registers.")
Reported-by: STAR Labs SG <info@starlabs.sg>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/r/20260410232651.559778-1-daniel@iogearbox.net
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Before v7.0 is released, fix a few issues with the CFI patchset,
merged earlier in v7.0-rc, that primarily affect interfaces to
non-kernel code:
- Improve the prctl() interface for per-task indirect branch landing
pad control to expand abbreviations and to resemble the speculation
control prctl() interface
- Expand the "LP" and "SS" abbreviations in the ptrace uapi header
file to "branch landing pad" and "shadow stack", to improve
readability
- Fix a typo in a CFI-related macro name in the ptrace uapi header
file
- Ensure that the indirect branch tracking state and shadow stack
state are unlocked immediately after an exec() on the new task so
that libc subsequently can control it
- While working in this area, clean up the kernel-internal,
cross-architecture prctl() function names by expanding the
abbreviations mentioned above
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Merge tag 'riscv-for-linus-v7.0-rc8' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux
Pull RISC-V updates from Paul Walmsley:
"Before v7.0 is released, fix a few issues with the CFI patchset,
merged earlier in v7.0-rc, that primarily affect interfaces to
non-kernel code:
- Improve the prctl() interface for per-task indirect branch landing
pad control to expand abbreviations and to resemble the speculation
control prctl() interface
- Expand the "LP" and "SS" abbreviations in the ptrace uapi header
file to "branch landing pad" and "shadow stack", to improve
readability
- Fix a typo in a CFI-related macro name in the ptrace uapi header
file
- Ensure that the indirect branch tracking state and shadow stack
state are unlocked immediately after an exec() on the new task so
that libc subsequently can control it
- While working in this area, clean up the kernel-internal,
cross-architecture prctl() function names by expanding the
abbreviations mentioned above"
* tag 'riscv-for-linus-v7.0-rc8' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux:
prctl: cfi: change the branch landing pad prctl()s to be more descriptive
riscv: ptrace: cfi: expand "SS" references to "shadow stack" in uapi headers
prctl: rename branch landing pad implementation functions to be more explicit
riscv: ptrace: expand "LP" references to "branch landing pads" in uapi headers
riscv: cfi: clear CFI lock status in start_thread()
riscv: ptrace: cfi: fix "PRACE" typo in uapi header
As a sanity check poison stack slots that stack liveness determined
to be dead, so that any read from such slots will cause program rejection.
If stack liveness logic is incorrect the poison can cause
valid program to be rejected, but it also will prevent unsafe program
to be accepted.
Allow global subprogs "read" poisoned stack slots.
The static stack liveness determined that subprog doesn't read certain
stack slots, but sizeof(arg_type) based global subprog validation
isn't accurate enough to know which slots will actually be read by
the callee, so it needs to check full sizeof(arg_type) at the caller.
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20260410-patch-set-v4-14-5d4eecb343db@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Rework func_instance identification and remove the dynamic liveness
API, completing the transition to fully static stack liveness analysis.
Replace callchain-based func_instance keys with (callsite, depth)
pairs. The full callchain (all ancestor callsites) is no longer part
of the hash key; only the immediate callsite and the call depth
matter. This does not lose precision in practice and simplifies the
data structure significantly: struct callchain is removed entirely,
func_instance stores just callsite, depth.
Drop must_write_acc propagation. Previously, must_write marks were
accumulated across successors and propagated to the caller via
propagate_to_outer_instance(). Instead, callee entry liveness
(live_before at subprog start) is pulled directly back to the
caller's callsite in analyze_subprog() after each callee returns.
Since (callsite, depth) instances are shared across different call
chains that invoke the same subprog at the same depth, must_write
marks from one call may be stale for another. To handle this,
analyze_subprog() records into a fresh_instance() when the instance
was already visited (must_write_initialized), then merge_instances()
combines the results: may_read is unioned, must_write is intersected.
This ensures only slots written on ALL paths through all call sites
are marked as guaranteed writes.
This replaces commit_stack_write_marks() logic.
Skip recursive descent into callees that receive no FP-derived
arguments (has_fp_args() check). This is needed because global
subprogram calls can push depth beyond MAX_CALL_FRAMES (max depth
is 64 for global calls but only 8 frames are accommodated for FP
passing). It also handles the case where a callback subprog cannot be
determined by argument tracking: such callbacks will be processed by
analyze_subprog() at depth 0 independently.
Update lookup_instance() (used by is_live_before queries) to search
for the func_instance with maximal depth at the corresponding
callsite, walking depth downward from frameno to 0. This accounts for
the fact that instance depth no longer corresponds 1:1 to
bpf_verifier_state->curframe, since skipped non-FP calls create gaps.
Remove the dynamic public liveness API from verifier.c:
- bpf_mark_stack_{read,write}(), bpf_reset/commit_stack_write_marks()
- bpf_update_live_stack(), bpf_reset_live_stack_callchain()
- All call sites in check_stack_{read,write}_fixed_off(),
check_stack_range_initialized(), mark_stack_slot_obj_read(),
mark/unmark_stack_slots_{dynptr,iter,irq_flag}()
- The per-instruction write mark accumulation in do_check()
- The bpf_update_live_stack() call in prepare_func_exit()
mark_stack_read() and mark_stack_write() become static functions in
liveness.c, called only from the static analysis pass. The
func_instance->updated and must_write_dropped flags are removed.
Remove spis_single_slot(), spis_one_bit() helpers from bpf_verifier.h
as they are no longer used.
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Tested-by: Paul Chaignon <paul.chaignon@gmail.com>
Link: https://lore.kernel.org/r/20260410-patch-set-v4-9-5d4eecb343db@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
After arg tracking reaches a fixed point, perform a single linear scan
over the converged at_in[] state and translate each memory access into
liveness read/write masks on the func_instance:
- Load/store instructions: FP-derived pointer's frame and offset(s)
are converted to half-slot masks targeting
per_frame_masks->{may_read,must_write}
- Helper/kfunc calls: record_call_access() queries
bpf_helper_stack_access_bytes() / bpf_kfunc_stack_access_bytes()
for each FP-derived argument to determine access size and direction.
Unknown access size (S64_MIN) conservatively marks all slots from
fp_off to fp+0 as read.
- Imprecise pointers (frame == ARG_IMPRECISE): conservatively mark
all slots in every frame covered by the pointer's frame bitmask
as fully read.
- Static subprog calls with unresolved arguments: conservatively mark
all frames as fully read.
Instead of a call to clean_live_states(), start cleaning the current
state continuously as registers and stack become dead since the static
analysis provides complete liveness information. This makes
clean_live_states() and bpf_verifier_state->cleaned unnecessary.
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20260410-patch-set-v4-8-5d4eecb343db@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
The analysis is a basis for static liveness tracking mechanism
introduced by the next two commits.
A forward fixed-point analysis that tracks which frame's FP each
register value is derived from, and at what byte offset. This is
needed because a callee can receive a pointer to its caller's stack
frame (e.g. r1 = fp-16 at the call site), then do *(u64 *)(r1 + 0)
inside the callee — a cross-frame stack access that the callee's local
liveness must attribute to the caller's stack.
Each register holds an arg_track value from a three-level lattice:
- Precise {frame=N, off=[o1,o2,...]} — known frame index and
up to 4 concrete byte offsets
- Offset-imprecise {frame=N, off_cnt=0} — known frame, unknown offset
- Fully-imprecise {frame=ARG_IMPRECISE, mask=bitmask} — unknown frame,
mask says which frames might be involved
At CFG merge points the lattice moves toward imprecision (same
frame+offset stays precise, same frame different offsets merges offset
sets or becomes offset-imprecise, different frames become
fully-imprecise with OR'd bitmask).
The analysis also tracks spills/fills to the callee's own stack
(at_stack_in/out), so FP derived values spilled and reloaded.
This pass is run recursively per call site: when subprog A calls B
with specific FP-derived arguments, B is re-analyzed with those entry
args. The recursion follows analyze_subprog -> compute_subprog_args ->
(for each call insn) -> analyze_subprog. Subprogs that receive no
FP-derived args are skipped during recursion and analyzed
independently at depth 0.
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20260410-patch-set-v4-7-5d4eecb343db@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Move the `updated` check and reset from bpf_update_live_stack() into
update_instance() itself, so callers outside the main loop can reuse
it. Similarly, move write_insn_idx assignment out of
reset_stack_write_marks() into its public caller, and thread insn_idx
as a parameter to commit_stack_write_marks() instead of reading it
from liveness->write_insn_idx. Drop the unused `env` parameter from
alloc_frame_masks() and mark_stack_read().
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20260410-patch-set-v4-6-5d4eecb343db@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Migrate clean_verifier_state() and its liveness queries from 8-byte
SPI granularity to 4-byte half-slot granularity.
In __clean_func_state(), each SPI is cleaned in two independent
halves:
- half_spi 2*i (lo): slot_type[0..3]
- half_spi 2*i+1 (hi): slot_type[4..7]
Slot types STACK_DYNPTR, STACK_ITER and STACK_IRQ_FLAG are never
cleaned, as their slot type markers are required by
destroy_if_dynptr_stack_slot(), is_iter_reg_valid_uninit() and
is_irq_flag_reg_valid_uninit() for correctness.
When only the hi half is dead, spilled_ptr metadata is destroyed and
the lo half's STACK_SPILL bytes are downgraded to STACK_MISC or
STACK_ZERO. When only the lo half is dead, spilled_ptr is preserved
because the hi half may still need it for state comparison.
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20260410-patch-set-v4-5-5d4eecb343db@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Convert liveness bitmask type from u64 to spis_t, doubling the number
of trackable stack slots from 64 to 128 to support 4-byte granularity.
Each 8-byte SPI now maps to two consecutive 4-byte sub-slots in the
bitmask: spi*2 half and spi*2+1 half. In verifier.c,
check_stack_write_fixed_off() now reports 4-byte aligned writes of
4-byte writes as half-slot marks and 8-byte aligned 8-byte writes as
two slots. Similar logic applied in check_stack_read_fixed_off().
Queries (is_live_before) are not yet migrated to half-slot
granularity.
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20260410-patch-set-v4-4-5d4eecb343db@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Subprogram name can be computed from function info and BTF, but it is
convenient to have the name readily available for logging purposes.
Update comment saying that bpf_subprog_info->start has to be the first
field, this is no longer true, relevant sites access .start field
by it's name.
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20260410-patch-set-v4-2-5d4eecb343db@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Calvin reported an odd NMI watchdog lockup which claims that the CPU locked
up in user space. He provided a reproducer, which sets up a timerfd based
timer and then rearms it in a loop with an absolute expiry time of 1ns.
As the expiry time is in the past, the timer ends up as the first expiring
timer in the per CPU hrtimer base and the clockevent device is programmed
with the minimum delta value. If the machine is fast enough, this ends up
in a endless loop of programming the delta value to the minimum value
defined by the clock event device, before the timer interrupt can fire,
which starves the interrupt and consequently triggers the lockup detector
because the hrtimer callback of the lockup mechanism is never invoked.
As a first step to prevent this, avoid reprogramming the clock event device
when:
- a forced minimum delta event is pending
- the new expiry delta is less then or equal to the minimum delta
Thanks to Calvin for providing the reproducer and to Borislav for testing
and providing data from his Zen5 machine.
The problem is not limited to Zen5, but depending on the underlying
clock event device (e.g. TSC deadline timer on Intel) and the CPU speed
not necessarily observable.
This change serves only as the last resort and further changes will be made
to prevent this scenario earlier in the call chain as far as possible.
[ tglx: Updated to restore the old behaviour vs. !force and delta <= 0 and
fixed up the tick-broadcast handlers as pointed out by Borislav ]
Fixes: d316c57ff6 ("[PATCH] clockevents: add core functionality")
Reported-by: Calvin Owens <calvin@wbinvd.org>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Tested-by: Calvin Owens <calvin@wbinvd.org>
Tested-by: Borislav Petkov <bp@alien8.de>
Link: https://lore.kernel.org/lkml/acMe-QZUel-bBYUh@mozart.vkv.me/
Link: https://patch.msgid.link/20260407083247.562657657@kernel.org
Holding the per-VMA lock across the BPF program body creates a lock
ordering problem when helpers acquire locks that depend on mmap_lock:
vm_lock -> i_rwsem -> mmap_lock -> vm_lock
Snapshot the VMA under the per-VMA lock in _next() via memcpy(), then
drop the lock before returning. The BPF program accesses only the
snapshot.
The verifier only trusts vm_mm and vm_file pointers (see
BTF_TYPE_SAFE_TRUSTED_OR_NULL in verifier.c). vm_file is reference-
counted with get_file() under the lock and released via fput() on the
next iteration or in _destroy(). vm_mm is already correct because
lock_vma_under_rcu() verifies vma->vm_mm == mm. All other pointers
are left as-is by memcpy() since the verifier treats them as untrusted.
Fixes: 4ac4546821 ("bpf: Introduce task_vma open-coded iterator kfuncs")
Signed-off-by: Puranjay Mohan <puranjay@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Mykyta Yatsenko <yatsenko@meta.com>
Link: https://lore.kernel.org/r/20260408154539.3832150-4-puranjay@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
The open-coded task_vma iterator holds mmap_lock for the entire duration
of iteration, increasing contention on this highly contended lock.
Switch to per-VMA locking. Find the next VMA via an RCU-protected maple
tree walk and lock it with lock_vma_under_rcu(). lock_next_vma() is not
used because its fallback takes mmap_read_lock(), and the iterator must
work in non-sleepable contexts.
lock_vma_under_rcu() is a point lookup (mas_walk) that finds the VMA
containing a given address but cannot iterate across gaps. An
RCU-protected vma_next() walk (mas_find) first locates the next VMA's
vm_start to pass to lock_vma_under_rcu().
Between the RCU walk and the lock, the VMA may be removed, shrunk, or
write-locked. On failure, advance past it using vm_end from the RCU
walk. Because the VMA slab is SLAB_TYPESAFE_BY_RCU, vm_end may be
stale; fall back to PAGE_SIZE advancement when it does not make forward
progress. Concurrent VMA insertions at addresses already passed by the
iterator are not detected.
CONFIG_PER_VMA_LOCK is required; return -EOPNOTSUPP without it.
Signed-off-by: Puranjay Mohan <puranjay@kernel.org>
Link: https://lore.kernel.org/r/20260408154539.3832150-3-puranjay@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
The open-coded task_vma iterator reads task->mm locklessly and acquires
mmap_read_trylock() but never calls mmget(). If the task exits
concurrently, the mm_struct can be freed as it is not
SLAB_TYPESAFE_BY_RCU, resulting in a use-after-free.
Safely read task->mm with a trylock on alloc_lock and acquire an mm
reference. Drop the reference via bpf_iter_mmput_async() in _destroy()
and error paths. bpf_iter_mmput_async() is a local wrapper around
mmput_async() with a fallback to mmput() on !CONFIG_MMU.
Reject irqs-disabled contexts (including NMI) up front. Operations used
by _next() and _destroy() (mmap_read_unlock, bpf_iter_mmput_async)
take spinlocks with IRQs disabled (pool->lock, pi_lock). Running from
NMI or from a tracepoint that fires with those locks held could
deadlock.
A trylock on alloc_lock is used instead of the blocking task_lock()
(get_task_mm) to avoid a deadlock when a softirq BPF program iterates
a task that already holds its alloc_lock on the same CPU.
Fixes: 4ac4546821 ("bpf: Introduce task_vma open-coded iterator kfuncs")
Signed-off-by: Puranjay Mohan <puranjay@kernel.org>
Link: https://lore.kernel.org/r/20260408154539.3832150-2-puranjay@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
The kf_tasks[] design assumes task-based SCX ops don't nest - if they
did, kf_tasks[0] would get clobbered. The old scx_kf_allow() WARN_ONCE
caught invalid nesting via kf_mask, but that machinery is gone now.
Add a WARN_ON_ONCE(current->scx.kf_tasks[0]) at the top of each
SCX_CALL_OP_TASK*() macro. Checking kf_tasks[0] alone is sufficient: all
three variants (SCX_CALL_OP_TASK, SCX_CALL_OP_TASK_RET,
SCX_CALL_OP_2TASKS_RET) write to kf_tasks[0], so a non-NULL value at
entry to any of the three means re-entry from somewhere in the family.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Andrea Righi <arighi@nvidia.com>
The "kf_allowed" framing on this helper comes from the old runtime
scx_kf_allowed() gate, which has been removed. Rename it to describe what it
actually does in the new model.
Pure rename, no functional change.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Andrea Righi <arighi@nvidia.com>
Now that scx_kfunc_context_filter enforces context-sensitive kfunc
restrictions at BPF load time, the per-task runtime enforcement via
scx_kf_mask is redundant. Remove it entirely:
- Delete enum scx_kf_mask, the kf_mask field on sched_ext_entity, and
the scx_kf_allow()/scx_kf_disallow()/scx_kf_allowed() helpers along
with the higher_bits()/highest_bit() helpers they used.
- Strip the @mask parameter (and the BUILD_BUG_ON checks) from the
SCX_CALL_OP[_RET]/SCX_CALL_OP_TASK[_RET]/SCX_CALL_OP_2TASKS_RET
macros and update every call site. Reflow call sites that were
wrapped only to fit the old 5-arg form and now collapse onto a single
line under ~100 cols.
- Remove the in-kfunc scx_kf_allowed() runtime checks from
scx_dsq_insert_preamble(), scx_dsq_move(), scx_bpf_dispatch_nr_slots(),
scx_bpf_dispatch_cancel(), scx_bpf_dsq_move_to_local___v2(),
scx_bpf_sub_dispatch(), scx_bpf_reenqueue_local(), and the per-call
guard inside select_cpu_from_kfunc().
scx_bpf_task_cgroup() and scx_kf_allowed_on_arg_tasks() were already
cleaned up in the "drop redundant rq-locked check" patch.
scx_kf_allowed_if_unlocked() was rewritten in the preceding "decouple"
patch. No further changes to those helpers here.
Co-developed-by: Juntong Deng <juntong.deng@outlook.com>
Signed-off-by: Juntong Deng <juntong.deng@outlook.com>
Signed-off-by: Cheng-Yang Chou <yphbchou0911@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Andrea Righi <arighi@nvidia.com>
Move enforcement of SCX context-sensitive kfunc restrictions from per-task
runtime kf_mask checks to BPF verifier-time filtering, using the BPF core's
struct_ops context information.
A shared .filter callback is attached to each context-sensitive BTF set
and consults a per-op allow table (scx_kf_allow_flags[]) indexed by SCX
ops member offset. Disallowed calls are now rejected at program load time
instead of at runtime.
The old model split reachability across two places: each SCX_CALL_OP*()
set bits naming its op context, and each kfunc's scx_kf_allowed() check
OR'd together the bits it accepted. A kfunc was callable when those two
masks overlapped. The new model transposes the result to the caller side -
each op's allow flags directly list the kfunc groups it may call. The old
bit assignments were:
Call-site bits:
ops.select_cpu = ENQUEUE | SELECT_CPU
ops.enqueue = ENQUEUE
ops.dispatch = DISPATCH
ops.cpu_release = CPU_RELEASE
Kfunc-group accepted bits:
enqueue group = ENQUEUE | DISPATCH
select_cpu group = SELECT_CPU | ENQUEUE
dispatch group = DISPATCH
cpu_release group = CPU_RELEASE
Intersecting them yields the reachability now expressed directly by
scx_kf_allow_flags[]:
ops.select_cpu -> SELECT_CPU | ENQUEUE
ops.enqueue -> SELECT_CPU | ENQUEUE
ops.dispatch -> ENQUEUE | DISPATCH
ops.cpu_release -> CPU_RELEASE
Unlocked ops carried no kf_mask bits and reached only unlocked kfuncs;
that maps directly to UNLOCKED in the new table.
Equivalence was checked by walking every (op, kfunc-group) combination
across SCX ops, SYSCALL, and non-SCX struct_ops callers against the old
scx_kf_allowed() runtime checks. With two intended exceptions (see below),
all combinations reach the same verdict; disallowed calls are now caught at
load time instead of firing scx_error() at runtime.
scx_bpf_dsq_move_set_slice() and scx_bpf_dsq_move_set_vtime() are
exceptions: they have no runtime check at all, but the new filter rejects
them from ops outside dispatch/unlocked. The affected cases are nonsensical
- the values these setters store are only read by
scx_bpf_dsq_move{,_vtime}(), which is itself restricted to
dispatch/unlocked, so a setter call from anywhere else was already dead
code.
Runtime scx_kf_mask enforcement is left in place by this patch and removed
in a follow-up.
Original-patch-by: Juntong Deng <juntong.deng@outlook.com>
Original-patch-by: Cheng-Yang Chou <yphbchou0911@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Andrea Righi <arighi@nvidia.com>
scx_kf_allowed_on_arg_tasks() runs both an scx_kf_allowed(__SCX_KF_RQ_LOCKED)
mask check and a kf_tasks[] check. After the preceding call-site fixes,
every SCX_CALL_OP_TASK*() invocation has kf_mask & __SCX_KF_RQ_LOCKED
non-zero, so the mask check is redundant whenever the kf_tasks[] check
passes. Drop it and simplify the helper to take only @sch and @p.
Fold the locking guarantee into the SCX_CALL_OP_TASK() comment block, which
scx_bpf_task_cgroup() now points to.
No functional change.
Extracted from a larger verifier-time kfunc context filter patch
originally written by Juntong Deng.
Original-patch-by: Juntong Deng <juntong.deng@outlook.com>
Cc: Cheng-Yang Chou <yphbchou0911@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Andrea Righi <arighi@nvidia.com>
scx_kf_allowed_if_unlocked() uses !current->scx.kf_mask as a proxy for "no
SCX-tracked lock held". kf_mask is removed in a follow-up patch, so its two
callers - select_cpu_from_kfunc() and scx_dsq_move() - need another basis.
Add a new bool scx_rq.in_select_cpu, set across the SCX_CALL_OP_TASK_RET
that invokes ops.select_cpu(), to capture the one case where SCX itself
holds no lock but try_to_wake_up() holds @p's pi_lock. Together with
scx_locked_rq(), it expresses the same accepted-context set.
select_cpu_from_kfunc() needs a runtime test because it has to take
different locking paths depending on context. Open-code as a three-way
branch. The unlocked branch takes raw_spin_lock_irqsave(&p->pi_lock)
directly - pi_lock alone is enough for the fields the kfunc reads, and is
lighter than task_rq_lock().
scx_dsq_move() doesn't really need a runtime test - its accepted contexts
could be enforced at verifier load time. But since the runtime state is
already there and using it keeps the upcoming load-time filter simpler, just
write it the same way: (scx_locked_rq() || in_select_cpu) &&
!kf_allowed(DISPATCH).
scx_kf_allowed_if_unlocked() is deleted with the conversions.
No semantic change.
v2: s/No functional change/No semantic change/ - the unlocked path now acquires
pi_lock instead of the heavier task_rq_lock() (Andrea Righi).
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Andrea Righi <arighi@nvidia.com>
sched_move_task() invokes ops.cgroup_move() inside task_rq_lock(tsk), so
@p's rq lock is held. The SCX_CALL_OP_TASK invocation mislabels this:
- kf_mask = SCX_KF_UNLOCKED (== 0), claiming no lock is held.
- rq = NULL, so update_locked_rq() doesn't run and scx_locked_rq()
returns NULL.
Switch to SCX_KF_REST and pass task_rq(p), matching ops.set_cpumask()
from set_cpus_allowed_scx().
Three effects:
- scx_bpf_task_cgroup() becomes callable (was rejected by
scx_kf_allowed(__SCX_KF_RQ_LOCKED)). Safe; rq lock is held.
- scx_bpf_dsq_move() is now rejected (was allowed via the unlocked
branch). Calling it while holding an unrelated task's rq lock is
risky; rejection is correct.
- scx_bpf_select_cpu_*() previously took the unlocked branch in
select_cpu_from_kfunc() and called task_rq_lock(p, &rf), which
would deadlock against the already-held pi_lock. Now it takes the
locked-rq branch and is rejected with -EPERM via the existing
kf_allowed(SCX_KF_SELECT_CPU | SCX_KF_ENQUEUE) check. Latent
deadlock fix.
No in-tree scheduler is known to call any of these from ops.cgroup_move().
v2: Add Fixes: tag (Andrea Righi).
Fixes: 18853ba782 ("sched_ext: Track currently locked rq")
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Andrea Righi <arighi@nvidia.com>
select_cpu_from_kfunc() has an extra scx_kf_allowed_if_unlocked() branch
that accepts calls from unlocked contexts and takes task_rq_lock() itself
- a "callable from unlocked" property encoded in the kfunc body rather
than in set membership. That's fine while the runtime check is the
authoritative gate, but the upcoming verifier-time filter uses set
membership as the source of truth and needs it to reflect every context
the kfunc may be called from.
Add the three select_cpu kfuncs to scx_kfunc_ids_unlocked so their full
set of callable contexts is captured by set membership. This follows the
existing dual-set convention used by scx_bpf_dsq_move{,_vtime} and
scx_bpf_dsq_move_set_{slice,vtime}, which are members of both
scx_kfunc_ids_dispatch and scx_kfunc_ids_unlocked.
While at it, add brief comments on each duplicate BTF_ID_FLAGS block
(including the pre-existing dsq_move ones) explaining the dual
membership.
No runtime behavior change: the runtime check in select_cpu_from_kfunc()
remains the authoritative gate until it is removed along with the rest
of the scx_kf_mask enforcement in a follow-up.
v2: Clarify dispatch-set comment to name scx_bpf_dsq_move*() explicitly so it
doesn't appear to cover scx_bpf_sub_dispatch() (Andrea Righi).
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Andrea Righi <arighi@nvidia.com>
The select_cpu kfuncs - scx_bpf_select_cpu_dfl(), scx_bpf_select_cpu_and()
and __scx_bpf_select_cpu_and() - take task_rq_lock() internally. Exposing
them via scx_kfunc_set_idle to BPF_PROG_TYPE_TRACING is unsafe: arbitrary
tracing contexts (kprobes, tracepoints, fentry, LSM) may run with @p's
pi_lock state unknown.
Move them out of scx_kfunc_ids_idle into a new scx_kfunc_ids_select_cpu
set registered only for STRUCT_OPS and SYSCALL.
Extracted from a larger verifier-time kfunc context filter patch
originally written by Juntong Deng.
Original-patch-by: Juntong Deng <juntong.deng@outlook.com>
Cc: Cheng-Yang Chou <yphbchou0911@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Andrea Righi <arighi@nvidia.com>
* arm64/for-next/perf:
: Perf updates
perf/arm-cmn: Fix resource_size_t printk specifier in arm_cmn_init_dtc()
perf/arm-cmn: Fix incorrect error check for devm_ioremap()
perf: add NVIDIA Tegra410 C2C PMU
perf: add NVIDIA Tegra410 CPU Memory Latency PMU
perf/arm_cspmu: nvidia: Add Tegra410 PCIE-TGT PMU
perf/arm_cspmu: nvidia: Add Tegra410 PCIE PMU
perf/arm_cspmu: Add arm_cspmu_acpi_dev_get
perf/arm_cspmu: nvidia: Add Tegra410 UCF PMU
perf/arm_cspmu: nvidia: Rename doc to Tegra241
perf/arm-cmn: Stop claiming entire iomem region
arm64: cpufeature: Use pmuv3_implemented() function
arm64: cpufeature: Make PMUVer and PerfMon unsigned
KVM: arm64: Read PMUVer as unsigned
* arm64/for-next/read-once:
: Fixes for __READ_ONCE() with CONFIG_LTO=y
arm64, compiler-context-analysis: Permit alias analysis through __READ_ONCE() with CONFIG_LTO=y
arm64: Optimize __READ_ONCE() with CONFIG_LTO=y
* for-next/misc:
: Miscellaneous cleanups/fixes
arm64: rsi: use linear-map alias for realm config buffer
arm64: Kconfig: fix duplicate word in CMDLINE help text
arm64: mte: Skip TFSR_EL1 checks and barriers in synchronous tag check mode
arm64/hwcap: Generate the KERNEL_HWCAP_ definitions for the hwcaps
arm64: kexec: Remove duplicate allocation for trans_pgd
arm64: mm: Use generic enum pgtable_level
arm64: scs: Remove redundant save/restore of SCS SP on entry to/from EL0
arm64: remove ARCH_INLINE_*
* for-next/tlbflush:
: Refactor the arm64 TLB invalidation API and implementation
arm64: mm: __ptep_set_access_flags must hint correct TTL
arm64: mm: Provide level hint for flush_tlb_page()
arm64: mm: Wrap flush_tlb_page() around __do_flush_tlb_range()
arm64: mm: More flags for __flush_tlb_range()
arm64: mm: Refactor __flush_tlb_range() to take flags
arm64: mm: Refactor flush_tlb_page() to use __tlbi_level_asid()
arm64: mm: Simplify __flush_tlb_range_limit_excess()
arm64: mm: Simplify __TLBI_RANGE_NUM() macro
arm64: mm: Re-implement the __flush_tlb_range_op macro in C
arm64: mm: Inline __TLBI_VADDR_RANGE() into __tlbi_range()
arm64: mm: Push __TLBI_VADDR() into __tlbi_level()
arm64: mm: Implicitly invalidate user ASID based on TLBI operation
arm64: mm: Introduce a C wrapper for by-range TLB invalidation
arm64: mm: Re-implement the __tlbi_level macro as a C function
* for-next/ttbr-macros-cleanup:
: Cleanups of the TTBR1_* macros
arm64/mm: Directly use TTBRx_EL1_CnP
arm64/mm: Directly use TTBRx_EL1_ASID_MASK
arm64/mm: Describe TTBR1_BADDR_4852_OFFSET
* for-next/kselftest:
: arm64 kselftest updates
selftests/arm64: Implement cmpbr_sigill() to hwcap test
* for-next/feat_lsui:
: Futex support using FEAT_LSUI instructions to avoid toggling PAN
arm64: armv8_deprecated: Disable swp emulation when FEAT_LSUI present
arm64: Kconfig: Add support for LSUI
KVM: arm64: Use CAST instruction for swapping guest descriptor
arm64: futex: Support futex with FEAT_LSUI
arm64: futex: Refactor futex atomic operation
KVM: arm64: kselftest: set_id_regs: Add test for FEAT_LSUI
KVM: arm64: Expose FEAT_LSUI to guests
arm64: cpufeature: Add FEAT_LSUI
* for-next/mpam: (40 commits)
: Expose MPAM to user-space via resctrl:
: - Add architecture context-switch and hiding of the feature from KVM.
: - Add interface to allow MPAM to be exposed to user-space using resctrl.
: - Add errata workaoround for some existing platforms.
: - Add documentation for using MPAM and what shape of platforms can use resctrl
arm64: mpam: Add initial MPAM documentation
arm_mpam: Quirk CMN-650's CSU NRDY behaviour
arm_mpam: Add workaround for T241-MPAM-6
arm_mpam: Add workaround for T241-MPAM-4
arm_mpam: Add workaround for T241-MPAM-1
arm_mpam: Add quirk framework
arm_mpam: resctrl: Call resctrl_init() on platforms that can support resctrl
arm64: mpam: Select ARCH_HAS_CPU_RESCTRL
arm_mpam: resctrl: Add empty definitions for assorted resctrl functions
arm_mpam: resctrl: Update the rmid reallocation limit
arm_mpam: resctrl: Add resctrl_arch_rmid_read()
arm_mpam: resctrl: Allow resctrl to allocate monitors
arm_mpam: resctrl: Add support for csu counters
arm_mpam: resctrl: Add monitor initialisation and domain boilerplate
arm_mpam: resctrl: Add kunit test for control format conversions
arm_mpam: resctrl: Add support for 'MB' resource
arm_mpam: resctrl: Wait for cacheinfo to be ready
arm_mpam: resctrl: Add rmid index helpers
arm_mpam: resctrl: Convert to/from MPAMs fixed-point formats
arm_mpam: resctrl: Hide CDP emulation behind CONFIG_EXPERT
...
* for-next/hotplug-batched-tlbi:
: arm64/mm: Enable batched TLB flush in unmap_hotplug_range()
arm64/mm: Reject memory removal that splits a kernel leaf mapping
arm64/mm: Enable batched TLB flush in unmap_hotplug_range()
* for-next/bbml2-fixes:
: Fixes for realm guest and BBML2_NOABORT
arm64: mm: Remove pmd_sect() and pud_sect()
arm64: mm: Handle invalid large leaf mappings correctly
arm64: mm: Fix rodata=full block mapping support for realm guests
* for-next/sysreg:
: arm64 sysreg updates
arm64/sysreg: Update ID_AA64SMFR0_EL1 description to DDI0601 2025-12
arm64/sysreg: Update ID_AA64ZFR0_EL1 description to DDI0601 2025-12
arm64/sysreg: Update ID_AA64FPFR0_EL1 description to DDI0601 2025-12
arm64/sysreg: Update ID_AA64ISAR2_EL1 description to DDI0601 2025-12
arm64/sysreg: Update ID_AA64ISAR0_EL1 description to DDI0601 2025-12
arm64/sysreg: Update SMIDR_EL1 to DDI0601 2025-06
* for-next/generic-entry:
: More arm64 refactoring towards using the generic entry code
arm64: Check DAIF (and PMR) at task-switch time
arm64: entry: Use split preemption logic
arm64: entry: Use irqentry_{enter_from,exit_to}_kernel_mode()
arm64: entry: Consistently prefix arm64-specific wrappers
arm64: entry: Don't preempt with SError or Debug masked
entry: Split preemption from irqentry_exit_to_kernel_mode()
entry: Split kernel mode logic from irqentry_{enter,exit}()
entry: Move irqentry_enter() prototype later
entry: Remove local_irq_{enable,disable}_exit_to_user()
entry: Fix stale comment for irqentry_enter()
* for-next/acpi:
: arm64 ACPI updates
ACPI: AGDI: fix missing newline in error message
Merge cpuidle updates, OPP (operating performance points) library
updates, and updates related to system suspend and hibernation for
7.1-rc1:
- Refine stopped tick handling in the menu cpuidle governor and
rearrange stopped tick handling in the teo cpuidle governor (Rafael
Wysocki)
- Add Panther Lake C-states table to the intel_idle driver (Artem
Bityutskiy)
- Clean up dead dependencies on CPU_IDLE in Kconfig (Julian Braha)
- Simplify cpuidle_register_device() with guard() (Huisong Li)
- Use performance level if available to distinguish between rates in
OPP debugfs (Manivannan Sadhasivam)
- Fix scoped_guard in dev_pm_opp_xlate_required_opp() (Viresh Kumar)
- Return -ENODATA if the snapshot image is not loaded (Alberto Garcia)
- Remove inclusion of crypto/hash.h from hibernate_64.c on x86 (Eric
Biggers)
* pm-cpuidle:
cpuidle: Simplify cpuidle_register_device() with guard()
cpuidle: clean up dead dependencies on CPU_IDLE in Kconfig
intel_idle: Add Panther Lake C-states table
cpuidle: governors: teo: Rearrange stopped tick handling
cpuidle: governors: menu: Refine stopped tick handling
* pm-opp:
OPP: Move break out of scoped_guard in dev_pm_opp_xlate_required_opp()
OPP: debugfs: Use performance level if available to distinguish between rates
* pm-sleep:
PM: hibernate: return -ENODATA if the snapshot image is not loaded
PM: hibernate: x86: Remove inclusion of crypto/hash.h
Merge cpufreq updates for 7.1-rc1:
- Update qcom-hw DT bindings to include Eliza hardware (Abel Vesa)
- Update cpufreq-dt-platdev blocklist (Faruque Ansari)
- Minor updates to driver and dt-bindings for Tegra (Thierry Reding,
Rosen Penev)
- Add MAINTAINERS entry for CPPC driver (Viresh Kumar)
- Add support for new features: CPPC performance priority, Dynamic EPP,
Raw EPP, and new unit tests for them to amd-pstate (Gautham Shenoy,
Mario Limonciello)
- Fix sysfs files being present when HW missing and broken/outdated
documentation in the amd-pstate driver (Ninad Naik, Gautham Shenoy)
- Pass the policy to cpufreq_driver->adjust_perf() to avoid using
cpufreq_cpu_get() in the .adjust_perf() callback in amd-pstate which
leads to a scheduling-while-atomic bug (K Prateek Nayak)
- Clean up dead code in Kconfig for cpufreq (Julian Braha)
- Remove max_freq_req update for pre-existing cpufreq policy and add a
boost_freq_req QoS request to save the boost constraint instead of
overwriting the last scaling_max_freq constraint (Pierre Gondois)
- Embed cpufreq QoS freq_req objects in cpufreq policy so they all
are allocated in one go along with the policy to simplify lifetime
rules and avoid error handling issues (Viresh Kumar)
- Use DMI max speed when CPPC is unavailable in the acpi-cpufreq
scaling driver (Henry Tseng)
- Switch policy_is_shared() in cpufreq to using cpumask_nth() instead
of cpumask_weight() because the former is more efficient (Yury Norov)
- Use sysfs_emit() in sysfs show functions for cpufreq governor
attributes (Thorsten Blum)
- Update intel_pstate to stop returning an error when "off" is written
to its status sysfs attribute while the driver is already off (Fabio
De Francesco)
- Include current frequency in the debug message printed by
__cpufreq_driver_target() (Pengjie Zhang)
* pm-cpufreq: (38 commits)
cpufreq/amd-pstate: Add POWER_SUPPLY select for dynamic EPP
MAINTAINERS: amd-pstate: Step down as maintainer, add Prateek as reviewer
cpufreq: Pass the policy to cpufreq_driver->adjust_perf()
cpufreq/amd-pstate: Pass the policy to amd_pstate_update()
cpufreq/amd-pstate-ut: Add a unit test for raw EPP
cpufreq/amd-pstate: Add support for raw EPP writes
cpufreq/amd-pstate: Add support for platform profile class
cpufreq/amd-pstate: add kernel command line to override dynamic epp
cpufreq/amd-pstate: Add dynamic energy performance preference
Documentation: amd-pstate: fix dead links in the reference section
cpufreq/amd-pstate: Cache the max frequency in cpudata
Documentation/amd-pstate: Add documentation for amd_pstate_floor_{freq,count}
Documentation/amd-pstate: List amd_pstate_prefcore_ranking sysfs file
Documentation/amd-pstate: List amd_pstate_hw_prefcore sysfs file
amd-pstate-ut: Add a testcase to validate the visibility of driver attributes
amd-pstate-ut: Add module parameter to select testcases
amd-pstate: Introduce a tracepoint trace_amd_pstate_cppc_req2()
amd-pstate: Add sysfs support for floor_freq and floor_count
amd-pstate: Add support for CPPC_REQ2 and FLOOR_PERF
x86/cpufeatures: Add AMD CPPC Performance Priority feature.
...
The format string says "device %p ... rdma cgroup %p" but the arguments
were passed as (cg, device), printing them in the wrong order.
Signed-off-by: cuitao <cuitao@kylinos.cn>
Signed-off-by: Tejun Heo <tj@kernel.org>
When querying info for an offloaded BPF map or program,
bpf_map_offload_info_fill_ns() and bpf_prog_offload_info_fill_ns()
obtain the network namespace with get_net(dev_net(offmap->netdev)).
However, the associated netdev's netns may be racing with teardown
during netns destruction. If the netns refcount has already reached 0,
get_net() performs a refcount_t increment on 0, triggering:
refcount_t: addition on 0; use-after-free.
Although rtnl_lock and bpf_devs_lock ensure the netdev pointer remains
valid, they cannot prevent the netns refcount from reaching zero.
Fix this by using maybe_get_net() instead of get_net(). maybe_get_net()
uses refcount_inc_not_zero() and returns NULL if the refcount is already
zero, which causes ns_get_path_cb() to fail and the caller to return
-ENOENT -- the correct behavior when the netns is being destroyed.
Fixes: 675fc275a3 ("bpf: offload: report device information for offloaded programs")
Fixes: 52775b33bb ("bpf: offload: report device information about offloaded maps")
Reported-by: Yinhao Hu <dddddd@hust.edu.cn>
Reported-by: Kaiyan Mei <M202472210@hust.edu.cn>
Reviewed-by: Dongliang Mu <dzm91@hust.edu.cn>
Closes: https://lore.kernel.org/bpf/f0aa3678-79c9-47ae-9e8c-02a3d1df160a@hust.edu.cn/
Signed-off-by: Jiayuan Chen <jiayuan.chen@linux.dev>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/r/20260409023733.168050-1-jiayuan.chen@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
When a pkt pointer acquires AT_PKT_END or BEYOND_PKT_END range from
a comparison, and then, known-constant arithmetic is performed,
adjust_ptr_min_max_vals() copies the stale range via dst_reg->raw =
ptr_reg->raw without clearing the negative reg->range sentinel values.
This lets is_pkt_ptr_branch_taken() choose one branch direction and
skip going through the other. Fix this by clearing negative pkt range
values (that is, AT_PKT_END and BEYOND_PKT_END) after arithmetic on
pkt pointers. This ensures is_pkt_ptr_branch_taken() returns unknown
and both branches are properly verified.
Fixes: 6d94e741a8 ("bpf: Support for pointers beyond pkt_end.")
Reported-by: STAR Labs SG <info@starlabs.sg>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/r/20260409155016.536608-1-daniel@iogearbox.net
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
A fix for DMA-mapping subsystem, which hides annoying, false-positive
warnings from DMA-API debug on coherent platforms like x86_64 (Mikhail
Gavrilov).
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Merge tag 'dma-mapping-7.0-2026-04-09' of git://git.kernel.org/pub/scm/linux/kernel/git/mszyprowski/linux
Pull dma-mapping fix from Marek Szyprowski:
"A fix for DMA-mapping subsystem, which hides annoying, false-positive
warnings from DMA-API debug on coherent platforms like x86_64 (Mikhail
Gavrilov)"
* tag 'dma-mapping-7.0-2026-04-09' of git://git.kernel.org/pub/scm/linux/kernel/git/mszyprowski/linux:
dma-debug: suppress cacheline overlap warning when arch has no DMA alignment requirement
Provide a debugfs directory llc_balancing, and a knob named
"enabled" under it to allow the user to turn off and on the
cache aware scheduling at runtime.
Suggested-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Chen Yu <yu.c.chen@intel.com>
Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/0aa56f7fc48db2f8f700cd1aa34dedd0ec88351b.1775065312.git.tim.c.chen@linux.intel.com
Introduce sched_cache_present to enable cache aware scheduling for
multi LLCs NUMA node Cache-aware load balancing should only be
enabled if there are more than 1 LLCs within 1 NUMA node.
sched_cache_present is introduced to indicate whether this
platform supports this topology.
Test results:
The first test platform is a 2 socket Intel Sapphire Rapids with 30
cores per socket. The DRAM interleaving is enabled in the BIOS so it
essential has one NUMA node with two last level caches. There are 60
CPUs associated with each last level cache.
The second test platform is a AMD Genoa. There are 4 Nodes and 32 CPUs
per node. Each node has 2 CCXs and each CCX has 16 CPUs.
hackbench/schbench/netperf/stream/stress-ng/chacha20 were launched
on these two platforms.
[TL;DR]
Sappire Rapids:
hackbench shows significant improvement when the number of
different active threads is below the capacity of a LLC.
schbench shows limitted wakeup latency improvement.
ChaCha20-xiangshan(risc-v simulator) shows good throughput
improvement. No obvious difference was observed in
netperf/stream/stress-ng in Hmean.
Genoa:
Significant improvement is observed in hackbench when
the active number of threads is lower than the number
of CPUs within 1 LLC. On v2, Aaron reported improvement
of hackbench/redis when system is underloaded.
ChaCha20-xiangshan shows huge throughput improvement.
Phoronix has tested v1 and shows good improvements in 30+
cases[3]. No obvious difference was observed in
netperf/stream/stress-ng in Hmean.
Detail:
Due to length constraints, data without much difference with
baseline is not presented.
Sapphire Rapids:
[hackbench pipe]
================
case load baseline(std%) compare%( std%)
threads-pipe-10 1-groups 1.00 ( 1.22) +26.09 ( 1.10)
threads-pipe-10 2-groups 1.00 ( 4.90) +22.88 ( 0.18)
threads-pipe-10 4-groups 1.00 ( 2.07) +9.00 ( 3.49)
threads-pipe-10 8-groups 1.00 ( 8.13) +3.45 ( 3.62)
threads-pipe-16 1-groups 1.00 ( 2.11) +26.30 ( 0.08)
threads-pipe-16 2-groups 1.00 ( 15.13) -1.77 ( 11.89)
threads-pipe-16 4-groups 1.00 ( 4.37) +0.58 ( 7.99)
threads-pipe-16 8-groups 1.00 ( 2.88) +2.71 ( 3.50)
threads-pipe-2 1-groups 1.00 ( 9.40) +22.07 ( 0.71)
threads-pipe-2 2-groups 1.00 ( 9.99) +18.01 ( 0.95)
threads-pipe-2 4-groups 1.00 ( 3.98) +24.66 ( 0.96)
threads-pipe-2 8-groups 1.00 ( 7.00) +21.83 ( 0.23)
threads-pipe-20 1-groups 1.00 ( 1.03) +28.84 ( 0.21)
threads-pipe-20 2-groups 1.00 ( 4.42) +31.90 ( 3.15)
threads-pipe-20 4-groups 1.00 ( 9.97) +4.56 ( 1.69)
threads-pipe-20 8-groups 1.00 ( 1.87) +1.25 ( 0.74)
threads-pipe-4 1-groups 1.00 ( 4.48) +25.67 ( 0.78)
threads-pipe-4 2-groups 1.00 ( 9.14) +4.91 ( 2.08)
threads-pipe-4 4-groups 1.00 ( 7.68) +19.36 ( 1.53)
threads-pipe-4 8-groups 1.00 ( 10.79) +7.20 ( 12.20)
threads-pipe-8 1-groups 1.00 ( 4.69) +21.93 ( 0.03)
threads-pipe-8 2-groups 1.00 ( 1.16) +25.29 ( 0.65)
threads-pipe-8 4-groups 1.00 ( 2.23) -1.27 ( 3.62)
threads-pipe-8 8-groups 1.00 ( 4.65) -3.08 ( 2.75)
Note: The default number of fd in hackbench is changed from 20 to various
values to ensure that threads fit within a single LLC, especially on AMD
systems. Take "threads-pipe-8, 2-groups" for example, the number of fd
is 8, and 2 groups are created.
[schbench]
The 99th percentile wakeup latency shows some improvements when the
system is underload, while it does not bring much difference with
the increasing of system utilization.
99th Wakeup Latencies Base (mean std) Compare (mean std) Change
=========================================================================
thread=2 9.00(0.00) 9.00(1.73) 0.00%
thread=4 7.33(0.58) 6.33(0.58) +13.64%
thread=8 9.00(0.00) 7.67(1.15) +14.78%
thread=16 8.67(0.58) 8.67(1.53) 0.00%
thread=32 9.00(0.00) 7.00(0.00) +22.22%
thread=64 9.33(0.58) 9.67(0.58) -3.64%
thread=128 12.00(0.00) 12.00(0.00) 0.00%
[chacha20 on simulated risc-v]
baseline:
Host time spent: 67861ms
cache aware scheduling enabled:
Host time spent: 54441ms
Time reduced by 24%
Genoa:
[hackbench pipe]
The default number of fd is 20, which exceed the number of CPUs
in a LLC. So the fd is adjusted to 2, 4, 6, 8, 20 respectively.
Exclude the result with large run-to-run variance, 10% ~ 50%
improvement is observed when the system is underloaded:
[hackbench pipe]
================
case load baseline(std%) compare%( std%)
threads-pipe-2 1-groups 1.00 ( 2.89) +47.33 ( 1.20)
threads-pipe-2 2-groups 1.00 ( 3.88) +39.82 ( 0.61)
threads-pipe-2 4-groups 1.00 ( 8.76) +5.57 ( 13.10)
threads-pipe-20 1-groups 1.00 ( 4.61) +11.72 ( 1.06)
threads-pipe-20 2-groups 1.00 ( 6.18) +14.55 ( 1.47)
threads-pipe-20 4-groups 1.00 ( 2.99) +10.16 ( 4.49)
threads-pipe-4 1-groups 1.00 ( 4.23) +43.70 ( 2.14)
threads-pipe-4 2-groups 1.00 ( 3.68) +8.45 ( 4.04)
threads-pipe-4 4-groups 1.00 ( 17.72) +2.42 ( 1.14)
threads-pipe-6 1-groups 1.00 ( 3.10) +7.74 ( 3.83)
threads-pipe-6 2-groups 1.00 ( 3.42) +14.26 ( 4.53)
threads-pipe-6 4-groups 1.00 ( 10.34) +10.94 ( 7.12)
threads-pipe-8 1-groups 1.00 ( 4.21) +9.06 ( 4.43)
threads-pipe-8 2-groups 1.00 ( 1.88) +3.74 ( 0.58)
threads-pipe-8 4-groups 1.00 ( 2.78) +23.96 ( 1.18)
[chacha20 on simulated risc-v]
Host time spent: 54762ms
Host time spent: 28295ms
Time reduced by 48%
Suggested-by: Libo Chen <libchen@purestorage.com>
Suggested-by: Adam Li <adamli@os.amperecomputing.com>
Signed-off-by: Chen Yu <yu.c.chen@intel.com>
Co-developed-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/71972e12ab4f08aff422b31e34df09bdbd94de84.1775065312.git.tim.c.chen@linux.intel.com
During load balancing, make can_migrate_task()
consider a task's LLC preference.
Prevent a task from being moved out of its preferred LLC.
During the regular load balancing, if
the task cannot be migrated due to LLC locality, the
nr_balance_failed also should not be increased.
Suggested-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Suggested-by: K Prateek Nayak <kprateek.nayak@amd.com>
Co-developed-by: Chen Yu <yu.c.chen@intel.com>
Signed-off-by: Chen Yu <yu.c.chen@intel.com>
Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/53da65f3d59de31e1a1dc59a4093d8dd9d4dc206.1775065312.git.tim.c.chen@linux.intel.com
Cache aware scheduling mainly does two things:
1. Prevent task from migrating out of its preferred LLC if not
nessasary.
2. Migrating task to their preferred LLC if nessasary.
For 1:
In the generic load balance, if the busiest runqueue has only one task,
active balancing may be invoked to move it away. However, this migration
might break LLC locality.
Prevent regular load balance from migrating a task that
prefers the current LLC. The load level and imbalance do not warrant
breaking LLC preference per the can_migrate_llc() policy. Here, the
benefit of LLC locality outweighs the power efficiency gained from
migrating the only runnable task away.
Before migration, check whether the task is running on its preferred
LLC: Do not move a lone task to another LLC if it would move the task
away from its preferred LLC or cause excessive imbalance between LLCs.
For 2:
On the other hand, if the migration type is migrate_llc_task, it means
that there are tasks on the env->src_cpu that want to be migrated to
their preferred LLC, launch the active load balance anyway.
Co-developed-by: Chen Yu <yu.c.chen@intel.com>
Signed-off-by: Chen Yu <yu.c.chen@intel.com>
Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/9b816d8c27fabf2a9c0e1f61a6b90afe8ec4ad52.1775065312.git.tim.c.chen@linux.intel.com
Introduce a new migration type, migrate_llc_task, to support
cache-aware load balancing.
After identifying the busiest sched_group (having the most tasks
preferring the destination LLC), mark migrations with this type.
During load balancing, each runqueue in the busiest sched_group is
examined, and the runqueue with the highest number of tasks preferring
the destination CPU is selected as the busiest runqueue.
Co-developed-by: Chen Yu <yu.c.chen@intel.com>
Signed-off-by: Chen Yu <yu.c.chen@intel.com>
Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/b9df27c19cc5121ddb2a7d1be7f9d52fec1563dc.1775065312.git.tim.c.chen@linux.intel.com
During LLC load balancing, first check for tasks that prefer the
destination LLC and balance them to it before others.
Mark source sched groups containing tasks preferring non local LLCs
with the group_llc_balance flag. This ensures the load balancer later
pulls or pushes these tasks toward their preferred LLCs.
The priority of group_llc_balance is lower than that of group_overloaded
and higher than that of all other group types. This is because
group_llc_balance may exacerbate load imbalance, and if the LLC balancing
attempt fails, the nr_balance_failed mechanism will trigger other group
types to rebalance the load.
The load balancer selects the busiest sched_group and migrates tasks
to less busy groups to distribute load across CPUs.
With cache-aware scheduling enabled, the busiest sched_group is
the one with most tasks preferring the destination LLC. If
the group has the llc_balance flag set, cache aware load balancing is
triggered.
Introduce the helper function update_llc_busiest() to identify the
sched_group with the most tasks preferring the destination LLC.
Suggested-by: K Prateek Nayak <kprateek.nayak@amd.com>
Suggested-by: Madadi Vineeth Reddy <vineethr@linux.ibm.com>
Co-developed-by: Chen Yu <yu.c.chen@intel.com>
Signed-off-by: Chen Yu <yu.c.chen@intel.com>
Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/baa458f45eab3f602af090c6d6af63dc864f5ec6.1775065312.git.tim.c.chen@linux.intel.com
There is no need to check the local group twice for both
group_asym_packing and group_smt_balance. Adjust the code
to facilitate future checks for group types (cache-aware
load balancing) as well.
No functional changes are expected.
Suggested-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Co-developed-by: Chen Yu <yu.c.chen@intel.com>
Signed-off-by: Chen Yu <yu.c.chen@intel.com>
Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/99a57865c8ae1847087a5c00e92d24351cf3e5a8.1775065312.git.tim.c.chen@linux.intel.com
During LLC load balancing, tabulate the number of tasks on each runqueue
that prefer the LLC contains the env->dst_cpu in a sched group.
For example, consider a system with 4 LLC sched groups (LLC0 to LLC3)
balancing towards LLC3. LLC0 has 3 tasks preferring LLC3, LLC1 has
2, and LLC2 has 1. LLC0, having the most tasks preferring LLC3, is
selected as the busiest source to pick tasks from.
Within a source LLC, the total number of tasks preferring a destination
LLC is computed by summing counts across all CPUs in that LLC. For
instance, if LLC0 has CPU0 with 2 tasks and CPU1 with 1 task preferring
LLC3, the total for LLC0 is 3.
These statistics allow the load balancer to choose tasks from source
sched groups that best match their preferred LLCs.
Co-developed-by: Chen Yu <yu.c.chen@intel.com>
Signed-off-by: Chen Yu <yu.c.chen@intel.com>
Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/3d8502a33a753c4384b368f97f64ee70b1cea0db.1775065312.git.tim.c.chen@linux.intel.com
Calculate the number of tasks' LLC preferences for each runqueue.
This statistic is computed during task enqueue and dequeue
operations, and is used by the cache-aware load balancing.
Co-developed-by: Chen Yu <yu.c.chen@intel.com>
Signed-off-by: Chen Yu <yu.c.chen@intel.com>
Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/d15a64436d3acd19c5c53344c5e9d3d0b79b3233.1775065312.git.tim.c.chen@linux.intel.com
The lowest level of sched domain for each CPU is assigned an
array where each element tracks the number of tasks preferring
a given LLC, indexed from 0 to max_lid. Since each CPU
has its dedicated sd, this implies that each CPU will have
a dedicated task LLC preference counter.
For example, sd->llc_counts[3] = 2 signifies that there
are 2 tasks on this runqueue which prefer to run within LLC3.
The load balancer can use this information to identify busy
runqueues and migrate tasks to their preferred LLC domains.
This array will be reallocated at runtime during sched domain
rebuild.
Introduce the buffer allocation mechanism, and the statistics
will be calculated in the subsequent patch.
Note: the LLC preference statistics of each CPU are reset on
sched domain rebuild and may under count temporarily, until the
CPU becomes idle and the count is cleared. This is a trade off
to avoid complex data synchronization across sched domain builds.
Suggested-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Suggested-by: K Prateek Nayak <kprateek.nayak@amd.com>
Co-developed-by: Chen Yu <yu.c.chen@intel.com>
Signed-off-by: Chen Yu <yu.c.chen@intel.com>
Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/42e79eceb8cd6be8a032401d481d101913bc5703.1775065312.git.tim.c.chen@linux.intel.com
For each runqueue, track the number of tasks with an LLC preference
and how many of them are running on their preferred LLC. This mirrors
nr_numa_running and nr_preferred_running for NUMA balancing, and will
be used by cache-aware load balancing in later patches.
Co-developed-by: Chen Yu <yu.c.chen@intel.com>
Signed-off-by: Chen Yu <yu.c.chen@intel.com>
Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/459a37102f3d74a4e09ea58401d2094ac731d044.1775065312.git.tim.c.chen@linux.intel.com
With cache-aware scheduling enabled, each task is assigned a
preferred LLC ID. This allows quick identification of the LLC domain
where the task prefers to run, similar to numa_preferred_nid in
NUMA balancing.
Co-developed-by: Chen Yu <yu.c.chen@intel.com>
Signed-off-by: Chen Yu <yu.c.chen@intel.com>
Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/f2ceecba5858680349ad4ce9303a2121f0bb7272.1775065312.git.tim.c.chen@linux.intel.com
Introduce an index mapping between CPUs and their LLCs. This provides
a roughly continuous per LLC index needed for cache-aware load balancing in
later patches.
The existing per_cpu llc_id usually points to the first CPU of the
LLC domain, which is sparse and unsuitable as an array index. Using
llc_id directly would waste memory.
With the new mapping, CPUs in the same LLC share an approximate
continuous id:
per_cpu(llc_id, CPU=0...15) = 0
per_cpu(llc_id, CPU=16...31) = 1
per_cpu(llc_id, CPU=32...47) = 2
...
Note that the LLC IDs are allocated via bitmask, so the IDs may be
reused during CPU offline->online transitions.
Suggested-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Originally-by: K Prateek Nayak <kprateek.nayak@amd.com>
Co-developed-by: Chen Yu <yu.c.chen@intel.com>
Signed-off-by: Chen Yu <yu.c.chen@intel.com>
Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/047ef46339e4db497b54a89940a7ebedf27fcf28.1775065312.git.tim.c.chen@linux.intel.com
Cache-aware scheduling aggregates threads onto their preferred LLC,
mainly through load balancing. When the preferred LLC becomes
saturated, more threads are still placed there, increasing latency.
A mechanism is needed to limit aggregation so that the preferred LLC
does not become overloaded.
Introduce helper functions can_migrate_llc() and
can_migrate_llc_task() to enforce the LLC migration policy:
1. Aggregate a task to its preferred LLC if both source and
destination LLCs are not too busy, or if doing so will not
leave the preferred LLC much more imbalanced than the
non-preferred one (>20% utilization difference, a little
higher than the default imbalance_pct(17%) of the LLC domain
as hysteresis). Later this threshold will be turned into tunable
debugfs.
2. Allow moving a task from overloaded preferred LLC to a non
preferred LLC if this will not cause the non preferred LLC
to become too imbalanced to cause a later migration back.
3. If both LLCs are too busy, let the generic load balance to
spread the tasks.
Further (hysteresis)action could be taken in the future to prevent tasks
from being migrated into and out of the preferred LLC frequently (back and
forth): the threshold for migrating a task out of its preferred LLC should
be higher than that for migrating it into the LLC.
Signed-off-by: Chen Yu <yu.c.chen@intel.com>
Co-developed-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/d19b52589cdceaee5e625980959f4d1982d6d7c9.1775065312.git.tim.c.chen@linux.intel.com
When a system becomes busy and a process's preferred LLC is
saturated with too many threads, tasks within that LLC migrate
frequently. These in LLC migrations introduce latency and degrade
performance. To avoid this, task aggregation should be suppressed
when the preferred LLC is overloaded, which requires a metric to
indicate LLC utilization.
Record per LLC utilization/cpu capacity during periodic load
balancing. These statistics will be used in later patches to decide
whether tasks should be aggregated into their preferred LLC.
Signed-off-by: Chen Yu <yu.c.chen@intel.com>
Co-developed-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/a48151b3d57f2a42a5971aaead1b7f81e69229f4.1775065312.git.tim.c.chen@linux.intel.com
When NUMA balancing is enabled, the kernel currently iterates over all
online CPUs to aggregate process-wide occupancy data. On large systems,
this global scan introduces significant overhead.
To reduce scan latency, limit the search to a subset of relevant CPUs:
1. The task's preferred NUMA node.
2. The node where the task is currently running.
3. The node that contains the task's current preferred LLC..
While focusing solely on the preferred NUMA node is ideal, a
process-wide scan must remain flexible because the "preferred node"
is a per-task attribute. Different threads within the same process may
have different preferred nodes, causing the process-wide preference to
migrate. Maintaining a mask that covers both the preferred and active
running nodes ensures accuracy while significantly reducing the number of
CPUs inspected.
Future work may integrate numa_group to further refine task aggregation.
Suggested-by: Madadi Vineeth Reddy <vineethr@linux.ibm.com>
Signed-off-by: Chen Yu <yu.c.chen@intel.com>
Co-developed-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/57ed5fcec9b242803fe4ea2ce6e7f3de6a6efc6b.1775065312.git.tim.c.chen@linux.intel.com
Adds infrastructure to enable cache-aware load balancing,
which improves cache locality by grouping tasks that share resources
within the same cache domain. This reduces cache misses and improves
overall data access efficiency.
In this initial implementation, threads belonging to the same process
are treated as entities that likely share working sets. The mechanism
tracks per-process CPU occupancy across cache domains and attempts to
migrate threads toward cache-hot domains where their process already
has active threads, thereby enhancing locality.
This provides a basic model for cache affinity. While the current code
targets the last-level cache (LLC), the approach could be extended to
other domain types such as clusters (L2) or node-internal groupings.
At present, the mechanism selects the CPU within an LLC that has the
highest recent runtime. Subsequent patches in this series will use this
information in the load-balancing path to guide task placement toward
preferred LLCs.
In the future, more advanced policies could be integrated through NUMA
balancing-for example, migrating a task to its preferred LLC when spare
capacity exists, or swapping tasks across LLCs to improve cache affinity.
Grouping of tasks could also be generalized from that of a process
to be that of a NUMA group, or be user configurable.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Chen Yu <yu.c.chen@intel.com>
Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/6269a53221b9439b9ca00d18a9d1946fb64d8cff.1775065312.git.tim.c.chen@linux.intel.com
The local subprog pointer in create_jt() and visit_abnormal_return_insn()
was declared static.
It is unconditionally assigned via bpf_find_containing_subprog() before
every use. Thus, the static qualifier serves no purpose and rather creates
confusion. Just remove it.
Fixes: e40f5a6bf8 ("bpf: correct stack liveness for tail calls")
Fixes: 493d9e0d60 ("bpf, x86: add support for indirect jumps")
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Anton Protopopov <a.s.protopopov@gmail.com>
Link: https://lore.kernel.org/r/20260408191242.526279-3-daniel@iogearbox.net
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Usage of ld_{abs,ind} instructions got extended into subprogs some time
ago via commit 09b28d76ea ("bpf: Add abnormal return checks."). These
are only allowed in subprograms when the latter are BTF annotated and
have scalar return types.
The code generator in bpf_gen_ld_abs() has an abnormal exit path (r0=0 +
exit) from legacy cBPF times. While the enforcement is on scalar return
types, the verifier must also simulate the path of abnormal exit if the
packet data load via ld_{abs,ind} failed.
This is currently not the case. Fix it by having the verifier simulate
both success and failure paths, and extend it in similar ways as we do
for tail calls. The success path (r0=unknown, continue to next insn) is
pushed onto stack for later validation and the r0=0 and return to the
caller is done on the fall-through side.
Fixes: 09b28d76ea ("bpf: Add abnormal return checks.")
Reported-by: STAR Labs SG <info@starlabs.sg>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/r/20260408191242.526279-2-daniel@iogearbox.net
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Move find_linfo() as bpf_find_linfo() into core.c to allow for its use
in the verifier in subsequent patches.
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Acked-by: Mykyta Yatsenko <yatsenko@meta.com>
Link: https://lore.kernel.org/r/20260408021359.3786905-4-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Extract bpf_get_linfo_file_line as its own function so that the logic to
obtain the file, line, and line number for a given program can be shared
in subsequent patches.
Reviewed-by: Puranjay Mohan <puranjay@kernel.org>
Acked-by: Mykyta Yatsenko <yatsenko@meta.com>
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20260408021359.3786905-3-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
* kvm-arm64/hyp-tracing: (40 commits)
: .
: EL2 tracing support, adding both 'remote' ring-buffer
: infrastructure and the tracing itself, courtesy of
: Vincent Donnefort. From the cover letter:
:
: "The growing set of features supported by the hypervisor in protected
: mode necessitates debugging and profiling tools. Tracefs is the
: ideal candidate for this task:
:
: * It is simple to use and to script.
:
: * It is supported by various tools, from the trace-cmd CLI to the
: Android web-based perfetto.
:
: * The ring-buffer, where are stored trace events consists of linked
: pages, making it an ideal structure for sharing between kernel and
: hypervisor.
:
: This series first introduces a new generic way of creating remote events and
: remote buffers. Then it adds support to the pKVM hypervisor."
: .
tracing: selftests: Extend hotplug testing for trace remotes
tracing: Non-consuming read for trace remotes with an offline CPU
tracing: Adjust cmd_check_undefined to show unexpected undefined symbols
tracing: Restore accidentally removed SPDX tag
KVM: arm64: avoid unused-variable warning
tracing: Generate undef symbols allowlist for simple_ring_buffer
KVM: arm64: tracing: add ftrace dependency
tracing: add more symbols to whitelist
tracing: Update undefined symbols allow list for simple_ring_buffer
KVM: arm64: Fix out-of-tree build for nVHE/pKVM tracing
tracing: selftests: Add hypervisor trace remote tests
KVM: arm64: Add selftest event support to nVHE/pKVM hyp
KVM: arm64: Add hyp_enter/hyp_exit events to nVHE/pKVM hyp
KVM: arm64: Add event support to the nVHE/pKVM hyp and trace remote
KVM: arm64: Add trace reset to the nVHE/pKVM hyp
KVM: arm64: Sync boot clock with the nVHE/pKVM hyp
KVM: arm64: Add trace remote for the nVHE/pKVM hyp
KVM: arm64: Add tracing capability for the nVHE/pKVM hyp
KVM: arm64: Support unaligned fixmap in the pKVM hyp
KVM: arm64: Initialise hyp_nr_cpus for nVHE hyp
...
Signed-off-by: Marc Zyngier <maz@kernel.org>
Replace raw READ_ONCE() dereferences of pgtable entries with corresponding
standard page table accessors pxdp_get() in perf_get_pgtable_size(). These
accessors default to READ_ONCE() on platforms that don't override them. So
there is no functional change on such platforms.
However arm64 platform is being extended to support 128 bit page tables via
a new architecture feature i.e FEAT_D128 in which case READ_ONCE() will not
provide required single copy atomic access for 128 bit page table entries.
Although pxdp_get() accessors can later be overridden on arm64 platform to
extend required single copy atomicity support on 128 bit entries.
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260227062744.2215491-1-anshuman.khandual@arm.com
