Switch scx_bpf_kick_cid() from void to s32 so future cap enforcement can
surface failures. cid interface is introduced in this cycle and has no
external users, so the ABI change is safe. Subsequent patches will add
-EPERM returns when the calling sub-sched lacks the required cap on the
target cid.
v2: Return scx_cid_to_cpu()'s errno instead of -EINVAL. (Andrea)
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Andrea Righi <arighi@nvidia.com>
Add single-bit test and iterator over set cids in an scx_cmask.
v2: Bound scx_cmask_for_each_cid() to the active span. (sashiko AI)
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Andrea Righi <arighi@nvidia.com>
__scx_cmask_set(), __scx_cmask_contains() and __scx_cmask_word() take the
cmask first and the cid second. The kernel's bit and cpumask predicates put
the index first: test_bit(nr, addr), cpumask_test_cpu(cpu, mask). Reorder
the cmask helpers to (cid, mask) for consistency, ahead of new single-cid
ops added next. Mask-level ops (and/or/andnot/copy/subset/intersects) keep
(dst, src).
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Andrea Righi <arighi@nvidia.com>
syzbot triggered the following splat in remove_waiter() via
FUTEX_CMP_REQUEUE_PI:
KASAN: null-ptr-deref in range [0x0000000000000a88-0x0000000000000a8f]
class_raw_spinlock_constructor
remove_waiter+0x159/0x1200 kernel/locking/rtmutex.c:1561
rt_mutex_start_proxy_lock+0x103/0x120
futex_requeue+0x10e4/0x20d0
__x64_sys_futex+0x34f/0x4d0
task_blocks_on_rt_mutex() does not arm the waiter upon deadlock detection,
leaving waiter->task nil, where 3bfdc63936 ("rtmutex: Use waiter::task instead
of current in remove_waiter()") made this fatal.
Furthermore, rt_mutex_start_proxy_lock() should not be calling into remove_waiter()
upon a successfully grabbing the rtmutex. 1a1fb985f2 ("futex: Handle early deadlock
return correctly"), moved the remove_waiter() out of __rt_mutex_start_proxy_lock()
(where 'ret' was only ever 0 or < 0) into the wrapper. Tighten this check to
account for try_to_take_rt_mutex().
Fixes: 3bfdc63936 ("rtmutex: Use waiter::task instead of current in remove_waiter()")
Reported-by: syzbot+78147abe6c524f183ee9@syzkaller.appspotmail.com
Signed-off-by: Davidlohr Bueso <dave@stgolabs.net>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Cc: stable@vger.kernel.org
Closes: https://lore.kernel.org/all/69f114ac.050a0220.ac8b.0003.GAE@google.com/
Link: https://patch.msgid.link/20260507112913.1019537-1-dave@stgolabs.net
To remove the fixed limit on the number of preserved files per session,
transition the file metadata serialization from a single contiguous
memory block to a chain of linked blocks.
Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Reviewed-by: Pratyush Yadav (Google) <pratyush@kernel.org>
Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Link: https://patch.msgid.link/20260603154402.468928-11-pasha.tatashin@soleen.com
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Currently, the number of LUO sessions is limited by a fixed number of
pre-allocated pages for serialization (16 pages, allowing for ~819
sessions).
This limitation is problematic if LUO is used to support things such as
systemd file descriptor store, and would be used not just as VM memory
but to save other states on the machine.
Remove this limit by transitioning to a linked-block approach for
session metadata serialization. Instead of a single contiguous block,
session metadata is now stored in a chain of 16-page blocks. Each block
starts with a header containing the physical address of the next block
and the number of session entries in the current block.
Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Reviewed-by: Pratyush Yadav (Google) <pratyush@kernel.org>
Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Link: https://patch.msgid.link/20260603154402.468928-10-pasha.tatashin@soleen.com
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Currently, luo_session_setup_outgoing() allocates the session block and
sets its physical address in the header immediately. With upcoming
dynamic block-based session management, this makes the first block
different from the rest. Move the allocation to where it is first needed.
Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Reviewed-by: Pratyush Yadav (Google) <pratyush@kernel.org>
Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Link: https://patch.msgid.link/20260603154402.468928-9-pasha.tatashin@soleen.com
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Introduce a linked-block serialization mechanism for state handover.
Previously, LUO used contiguous memory blocks for serializing sessions
and files, which imposed limits on the total number of items that could
be preserved across a live update.
This commit adds the infrastructure for a more flexible, block-based
approach where serialized data is stored in a chain of linked blocks.
This is a generic KHO serialization block infrastructure that can be
used by multiple subsystems.
Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Link: https://patch.msgid.link/20260603154402.468928-8-pasha.tatashin@soleen.com
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Extract the logic for deserializing single entries for sessions into
separate helper functions. In preparation to a linked-block
serialization for sessions.
This is a pure code movement, no other changes intended.
Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Reviewed-by: Pratyush Yadav (Google) <pratyush@kernel.org>
Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Link: https://patch.msgid.link/20260603154402.468928-7-pasha.tatashin@soleen.com
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Extract the logic for deserializing single entries for files into
separate helper functions. In preparation to a linked-block
serialization for files.
This is a pure code movement, no other changes intended.
Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Reviewed-by: Pratyush Yadav (Google) <pratyush@kernel.org>
Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Link: https://patch.msgid.link/20260603154402.468928-6-pasha.tatashin@soleen.com
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Entirely remove the LUO FDT wrapper since the FDT only carries the
compatible string and the pointer to the centralized struct luo_ser.
Instead, register the struct luo_ser via the KHO raw subtree
API, placing the compatibility string inside the structure itself.
Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Reviewed-by: Pratyush Yadav (Google) <pratyush@kernel.org>
Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Link: https://patch.msgid.link/20260603154402.468928-5-pasha.tatashin@soleen.com
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Transition the LUO to ABI v2, which centralizes state management into a
single struct luo_ser header.
Previously, LUO state was spread across multiple FDT properties and
subnodes. ABI v2 simplifies this by placing all core state, including
the liveupdate number and physical addresses for sessions and FLB
headers into a centralized struct luo_ser.
Note that this change introduces a semantic difference: the sessions
and FLB serialization formats are no longer completely independent of
the core LUO. Their metadata (such as physical addresses for sessions
and FLB headers) is now coupled to and managed via the centralized
struct luo_ser.
Reviewed-by: Pratyush Yadav (Google) <pratyush@kernel.org>
Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Link: https://patch.msgid.link/20260603154402.468928-4-pasha.tatashin@soleen.com
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Refactoring luo_session_retrieve_fd() to avoid mixing automated
cleanup-style guards with goto-based resource release, which is not
recommended under the Linux kernel coding style.
Reviewed-by: Pratyush Yadav (Google) <pratyush@kernel.org>
Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Link: https://patch.msgid.link/20260603154402.468928-3-pasha.tatashin@soleen.com
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
This improves type safety and aligns the in-memory file_set->count with
the serialized count type. It avoids potential truncation or sign
conversion mismatch issues.
Reviewed-by: Pratyush Yadav (Google) <pratyush@kernel.org>
Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Link: https://patch.msgid.link/20260603154402.468928-2-pasha.tatashin@soleen.com
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
One cpuset fix and a maintenance update, both low-risk:
- Fix cpuset partition CPU accounting under sibling CPU exclusion that could
produce wrong CPU assignments and trigger scheduling-domain warnings.
Includes selftests.
- Update an email address in MAINTAINERS.
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Merge tag 'cgroup-for-7.1-rc6-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup
Pull cgroup fixes from Tejun Heo:
"One cpuset fix and a maintenance update, both low-risk:
- Fix cpuset partition CPU accounting under sibling CPU exclusion
that could produce wrong CPU assignments and trigger
scheduling-domain warnings. Includes selftests.
- Update an email address in MAINTAINERS"
* tag 'cgroup-for-7.1-rc6-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
cgroup/cpuset: Change Ridong's email
cgroup/cpuset: Add test cases for sibling CPU exclusion on partition update
cgroup/cpuset: Use effective_xcpus in partcmd_update add/del mask calculation
Two low-risk fixes:
- Drop a spurious warning that can fire during cgroup migration while a
sched_ext scheduler is loaded.
- Fix a drgn-based debug script that broke after scheduler state moved into
a per-scheduler struct.
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Merge tag 'sched_ext-for-7.1-rc6-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/sched_ext
Pull sched_ext fixes from Tejun Heo:
"Two low-risk fixes:
- Drop a spurious warning that can fire during cgroup migration while
a sched_ext scheduler is loaded
- Fix a drgn-based debug script that broke after scheduler state
moved into a per-scheduler struct"
* tag 'sched_ext-for-7.1-rc6-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/sched_ext:
sched_ext: Don't warn on NULL cgrp_moving_from in scx_cgroup_move_task()
tools/sched_ext: Fix scx_show_state per-scheduler state reads
In debug_dma_sync_sg_for_device(), when iterating over a scatterlist,
the debug entry population mistakenly uses the head of the scatterlist
'sg' to fetch the physical address via sg_phys(), instead of using the
current iterator variable 's'.
This causes dma-debug to track the physical address of the very first
scatterlist entry for all subsequent entries in the list.
Fix this by passing the correct loop iterator 's' to sg_phys()
Fixes: 9d4f645a1f ("dma-debug: store a phys_addr_t in struct dma_debug_entry")
Signed-off-by: Li RongQing <lirongqing@baidu.com>
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Link: https://lore.kernel.org/r/20260603123708.1665-1-lirongqing@baidu.com
Tracepoint handlers no longer run with preemption disabled by default
since a46023d561 ("tracing: Guard __DECLARE_TRACE() use of
__DO_TRACE_CALL() with SRCU-fast"), the opid monitor should now count 1
in the preemption count as preemption disabled.
Change the rule for preempt_off to preempt > 0.
Reviewed-by: Nam Cao <namcao@linutronix.de>
Link: https://lore.kernel.org/r/20260601153840.124372-11-gmonaco@redhat.com
Signed-off-by: Gabriele Monaco <gmonaco@redhat.com>
Hybrid automata monitors may start timers, depending on the model, these
may remain active on an exiting task and cause false positives or even
access freed memory.
Add an enable/disable hook in the HA code, currently only populated by
the per-task handler for registration and deregistration.
This hooks to the sched_process_exit event and ensures the timer is
stopped for every exiting task. The handler is enabled automatically but
may be disabled, for instance if the monitor uses the event for another
purpose (but should still manually ensure timers are stopped).
Fixes: f5587d1b6e ("rv: Add Hybrid Automata monitor type")
Reviewed-by: Nam Cao <namcao@linutronix.de>
Link: https://lore.kernel.org/r/20260601153840.124372-8-gmonaco@redhat.com
Signed-off-by: Gabriele Monaco <gmonaco@redhat.com>
The attributes variables extracted from syscalls in the helper are both
defined with the __user specifier although only the actual pointer to
user data should be marked.
Remove the __user specifier from attr.
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202604150820.Ny143u6X-lkp@intel.com
Fixes: b133207deb ("rv: Add nomiss deadline monitor")
Reviewed-by: Wen Yang <wen.yang@linux.dev>
Reviewed-by: Nam Cao <namcao@linutronix.de>
Link: https://lore.kernel.org/r/20260601153840.124372-2-gmonaco@redhat.com
Signed-off-by: Gabriele Monaco <gmonaco@redhat.com>
When the FUTEX_ROBUST_UNLOCK mechanism is used for unlocking (PI-)futexes,
then the unlock sequence in user space looks like this:
1) robust_list_set_op_pending(mutex);
2) robust_list_remove(mutex);
lval = gettid();
3) if (atomic_try_cmpxchg(&mutex->lock, lval, 0))
4) robust_list_clear_op_pending();
else
5) sys_futex(OP | FUTEX_ROBUST_UNLOCK, ....);
That still leaves a minimal race window between #3 and #4 where the mutex
could be acquired by some other task, which observes that it is the last
user and:
1) unmaps the mutex memory
2) maps a different file, which ends up covering the same address
When then the original task exits before reaching #5 then the kernel robust
list handling observes the pending op entry and tries to fix up user space.
In case that the newly mapped data contains the TID of the exiting thread
at the address of the mutex/futex the kernel will set the owner died bit in
that memory and therefore corrupt unrelated data.
On X86 this boils down to this simplified assembly sequence:
mov %esi,%eax // Load TID into EAX
xor %ecx,%ecx // Set ECX to 0
#3 lock cmpxchg %ecx,(%rdi) // Try the TID -> 0 transition
.Lstart:
jnz .Lend
#4 movq %rcx,(%rdx) // Clear list_op_pending
.Lend:
If the cmpxchg() succeeds and the task is interrupted before it can clear
list_op_pending in the robust list head (#4) and the task crashes in a
signal handler or gets killed then it ends up in do_exit() and subsequently
in the robust list handling, which then might run into the unmap/map issue
described above.
This is only relevant when user space was interrupted and a signal is
pending. The fix-up has to be done before signal delivery is attempted
because:
1) The signal might be fatal so get_signal() ends up in do_exit()
2) The signal handler might crash or the task is killed before returning
from the handler. At that point the instruction pointer in pt_regs is
not longer the instruction pointer of the initially interrupted unlock
sequence.
The right place to handle this is in __exit_to_user_mode_loop() before
invoking arch_do_signal_or_restart() as this covers obviously both
scenarios.
As this is only relevant when the task was interrupted in user space, this
is tied to RSEQ and the generic entry code as RSEQ keeps track of user
space interrupts unconditionally even if the task does not have a RSEQ
region installed. That makes the decision very lightweight:
if (current->rseq.user_irq && within(regs, csr->unlock_ip_range))
futex_fixup_robust_unlock(regs, csr);
futex_fixup_robust_unlock() then invokes a architecture specific function
to return the pending op pointer or NULL. The function evaluates the
register content to decide whether the pending ops pointer in the robust
list head needs to be cleared.
Assuming the above unlock sequence, then on x86 this decision is the
trivial evaluation of the zero flag:
return regs->eflags & X86_EFLAGS_ZF ? regs->dx : NULL;
Other architectures might need to do more complex evaluations due to LLSC,
but the approach is valid in general. The size of the pointer is determined
from the matching range struct, which covers both 32-bit and 64-bit builds
including COMPAT.
The unlock sequence is going to be placed in the VDSO so that the kernel
can keep everything synchronized, especially the register usage. The
resulting code sequence for user space is:
if (__vdso_futex_robust_list$SZ_try_unlock(lock, tid, &pending_op) != tid)
err = sys_futex($OP | FUTEX_ROBUST_UNLOCK,....);
Both the VDSO unlock and the kernel side unlock ensure that the pending_op
pointer is always cleared when the lock becomes unlocked.
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: André Almeida <andrealmeid@igalia.com>
Link: https://patch.msgid.link/20260602090535.773669210@kernel.org
There will be a VDSO function to unlock robust futexes in user space. The
unlock sequence is racy vs. clearing the list_pending_op pointer in the
tasks robust list head. To plug this race the kernel needs to know the
instruction window. As the VDSO is per MM the addresses are stored in
mm_struct::futex.
Architectures which implement support for this have to update these
addresses when the VDSO is (re)mapped and indicate the pending op pointer
size which is matching the IP.
Arguably this could be resolved by chasing mm->context->vdso->image, but
that's architecture specific and requires to touch quite some cache
lines. Having it in mm::futex reduces the cache line impact and avoids
having yet another set of architecture specific functionality.
To support multi size robust list applications (gaming) this provides two
ranges when COMPAT is enabled.
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: André Almeida <andrealmeid@igalia.com>
Link: https://patch.msgid.link/20260602090535.718926819@kernel.org
Unlocking robust non-PI futexes happens in user space with the following
sequence:
1) robust_list_set_op_pending(mutex);
2) robust_list_remove(mutex);
lval = 0;
3) lval = atomic_xchg(lock, lval);
4) if (lval & WAITERS)
5) sys_futex(WAKE,....);
6) robust_list_clear_op_pending();
That opens a window between #3 and #6 where the mutex could be acquired by
some other task which observes that it is the last user and:
A) unmaps the mutex memory
B) maps a different file, which ends up covering the same address
When the original task exits before reaching #6 then the kernel robust list
handling observes the pending op entry and tries to fix up user space.
In case that the newly mapped data contains the TID of the exiting thread
at the address of the mutex/futex the kernel will set the owner died bit in
that memory and therefore corrupting unrelated data.
PI futexes have a similar problem both for the non-contented user space
unlock and the in kernel unlock:
1) robust_list_set_op_pending(mutex);
2) robust_list_remove(mutex);
lval = gettid();
3) if (!atomic_try_cmpxchg(lock, lval, 0))
4) sys_futex(UNLOCK_PI,....);
5) robust_list_clear_op_pending();
Address the first part of the problem where the futexes have waiters and
need to enter the kernel anyway. Add a new FUTEX_ROBUST_UNLOCK flag, which
is valid for the sys_futex() FUTEX_UNLOCK_PI, FUTEX_WAKE, FUTEX_WAKE_BITSET
operations.
This deliberately omits FUTEX_WAKE_OP from this treatment as it's unclear
whether this is needed and there is no usage of it in glibc either to
investigate.
For the futex2 syscall family this needs to be implemented with a new
syscall.
The sys_futex() case [ab]uses the @uaddr2 argument to hand the pointer to
robust_list_head::list_pending_op into the kernel. This argument is only
evaluated when the FUTEX_ROBUST_UNLOCK bit is set and is therefore backward
compatible.
This is an explicit argument to avoid the lookup of the robust list pointer
and retrieving the pending op pointer from there. User space has the
pointer already available so it can just put it into the @uaddr2
argument. Aside of that this allows the usage of multiple robust lists in
the future without any changes to the internal functions as they just operate
on the provided pointer.
This requires a second flag FUTEX_ROBUST_LIST32 which indicates that the
robust list pointer points to an u32 and not to an u64. This is required
for two reasons:
1) sys_futex() has no compat variant
2) The gaming emulators use both both 64-bit and compat 32-bit robust
lists in the same 64-bit application
As a consequence 32-bit applications have to set this flag unconditionally
so they can run on a 64-bit kernel in compat mode unmodified. 32-bit
kernels return an error code when the flag is not set. 64-bit kernels will
happily clear the full 64 bits if user space fails to set it.
In case of FUTEX_UNLOCK_PI this clears the robust list pending op when the
unlock succeeded. In case of errors, the user space value is still locked
by the caller and therefore the above cannot happen.
In case of FUTEX_WAKE* this does the unlock of the futex in the kernel and
clears the robust list pending op when the unlock was successful. If not,
the user space value is still locked and user space has to deal with the
returned error. That means that the unlocking of non-PI robust futexes has
to use the same try_cmpxchg() unlock scheme as PI futexes.
If the clearing of the pending list op fails (fault) then the kernel clears
the registered robust list pointer if it matches to prevent that exit()
will try to handle invalid data. That's a valid paranoid decision because
the robust list head sits usually in the TLS and if the TLS is not longer
accessible then the chance for fixing up the resulting mess is very close
to zero.
The problem of non-contended unlocks still exists and will be addressed
separately.
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: André Almeida <andrealmeid@igalia.com>
Link: https://patch.msgid.link/20260602090535.670514505@kernel.org
The marker for PI futexes in the robust list is a hardcoded 0x1 which lacks
any sensible form of documentation.
Provide proper defines for the bit and the mask and fix up the usage
sites. Thereby convert the boolean pi argument into a modifier argument,
which allows new modifier bits to be trivially added and conveyed.
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Reviewed-by: André Almeida <andrealmeid@igalia.com>
Link: https://patch.msgid.link/20260602090535.458758556@kernel.org
Having all these members in mm_struct along with the required #ifdeffery is
annoying, does not allow efficient initializing of the data with
memset() and makes extending it tedious.
Move it into a data structure and fix up all usage sites.
The extra struct for the private hash is intentional to make integration of
other conditional mechanisms easier in terms of initialization and separation.
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260602090535.407756793@kernel.org
Nothing fails there. Mop up the leftovers of the early version of this,
which did an allocation.
While at it clean up the stubs and the #ifdef comments to make the header
file readable.
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260602090535.356789395@kernel.org
Having all these members in task_struct along with the required #ifdeffery
is annoying, does not allow efficient initializing of the data with
memset() and makes extending it tedious.
Move it into a data structure and fix up all usage sites.
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Reviewed-by: André Almeida <andrealmeid@igalia.com>
Link: https://patch.msgid.link/20260602090535.308220888@kernel.org
irqdesc_lock uses __DEFINE_UNLOCK_GUARD() directly with a custom
constructor that can set .lock to NULL.
In preparation for removing the NULL check from __DEFINE_UNLOCK_GUARD(),
move the NULL check into the irqdesc_lock unlock expression, making the
NULL handling explicit at the call site.
No functional change.
Signed-off-by: Dmitry Ilvokhin <d@ilvokhin.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Thomas Gleixner <tglx@kernel.org>
Link: https://patch.msgid.link/ab457810653e4356e29b2d74ba616478bd9328ad.1780064327.git.d@ilvokhin.com
In dma_direct_map_sg(), the case PCI_P2PDMA_MAP_THRU_HOST_BRIDGE
incorrectly used 'break' instead of falling through to MAP_NONE.
As a result, segments traversing the host bridge skipped the required
dma_direct_map_phys() call entirely, leaving sg->dma_address
uninitialized and leading to DMA failures. Fix this by using
'fallthrough;'.
Fixes: a25e7962db ("PCI/P2PDMA: Refactor the p2pdma mapping helpers")
Reviewed-by: Logan Gunthorpe <logang@deltatee.com>
Signed-off-by: Li RongQing <lirongqing@baidu.com>
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Link: https://lore.kernel.org/r/20260603013723.2439-1-lirongqing@baidu.com
The buf pointer was kmalloc_array()'d immediately after the parent
struct allocation, with the count (granule, validated to 1..1024 by
the ioctl) trivially available beforehand. Move buf to the struct
tail as a flexible array member and fold the two allocations into a
single kzalloc_flex(), dropping the kfree(params->buf) in both the
prepare error path and unprepare.
Add __counted_by for extra runtime analysis.
Assisted-by: Claude:Opus-4.7
Signed-off-by: Rosen Penev <rosenp@gmail.com>
Reviewed-by: Qinxin Xia <xiaqinxin@huawei.com>
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Link: https://lore.kernel.org/r/20260603031758.290538-1-rosenp@gmail.com
Patch series "mm: misc cleanups from __GFP_UNMAPPED series".
In v2 of the __GFP_UNMAPPED series [0], we realised that some of the
patches could potentially be merged as independent cleanups.
These are all independent of one another, if you think some are useful
cleanups and others are pointless churn, it should be fine to just pick
whatever subset you prefer.
No functional change intended.
This patch (of 4):
There are a couple of places that iterate over the freelists with
awareness of the data structures' layout.
It seems ideally, code outside of mm should not be aware of the page
allocator's freelists at all. But, this patch just doesn't hide them
completely, it's just a meek incremental step in that direction: provide a
macro to iterate over it without needing to be aware of the actual struct
fields.
Link: https://lore.kernel.org/20260513-page_alloc-unmapped-prep-v1-0-dacdf5402be8@google.com
Link: https://lore.kernel.org/20260513-page_alloc-unmapped-prep-v1-1-dacdf5402be8@google.com
Link: https://lore.kernel.org/all/20260320-page_alloc-unmapped-v2-0-28bf1bd54f41@google.com/ [0]
Signed-off-by: Brendan Jackman <jackmanb@google.com>
Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Reviewed-by: Vlastimil Babka (SUSE) <vbabka@kernel.org>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Barry Song <baohua@kernel.org>
Cc: David Hildenbrand <david@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kairui Song <kasong@tencent.com>
Cc: Len Brown <lenb@kernel.org>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Suren Baghdasaryan <surenb@google.com>
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>
A WARN fires when systemd's user manager writes "+cpu +memory +pids" to
its own subtree_control while a sched_ext scheduler is loaded:
WARNING: at kernel/sched/ext.c:3227 scx_cgroup_move_task+0xa8/0xb0
scx_cgroup_move_task+0xa8/0xb0
sched_move_task+0x134/0x290
cpu_cgroup_attach+0x39/0x70
cgroup_migrate_execute+0x37d/0x450
cgroup_update_dfl_csses+0x1e3/0x270
cgroup_subtree_control_write+0x3e7/0x440
scx_cgroup_can_attach() arms cgrp_moving_from only when a task's cpu
cgroup changes. It can still be NULL when scx_cgroup_move_task() runs,
through this sequence:
Step Result
--------------------------------- ----------------------------------
1. cpu enabled on cgroup G cpu css = A
2. cpu toggled off then on for G A killed, B created (same cgroup)
3. an exiting task keeps A alive migration skips it, A now stale
4. +memory migrates G stale A vs current B pulls cpu in
5. cpu attach runs for all tasks hits a live, cpu-unchanged task
6. scx_cgroup_move_task() on it cgrp_moving_from NULL -> WARN
The mismatch is that scx_cgroup_can_attach() keys on cgroup identity
while migration drives the move on css identity, so a NULL cgrp_moving_from
here is a legitimate css-only migration, not a missing prep.
The call is already gated on cgrp_moving_from, so just drop the warning.
ops.cgroup_prep_move() and ops.cgroup_move() stay paired.
Fixes: 8195136669 ("sched_ext: Add cgroup support")
Cc: stable@vger.kernel.org # v6.12+
Reported-by: Matt Fleming <mfleming@cloudflare.com>
Closes: https://lore.kernel.org/all/20260601124156.2205704-1-mfleming@cloudflare.com/
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Andrea Righi <arighi@nvidia.com>
When FUTEX_CMP_REQUEUE_PI requeues a non-top waiter that already owns the
target PI futex, task_blocks_on_rt_mutex() returns -EDEADLK before setting
waiter->task.
The subsequent remove_waiter() in rt_mutex_start_proxy_lock() dereferences
the NULL waiter->task, causing a kernel crash.
Add a self-deadlock check for non-top waiters before calling
rt_mutex_start_proxy_lock(), analogous to the top-waiter check in
futex_lock_pi_atomic().
Fixes: 3bfdc63936 ("rtmutex: Use waiter::task instead of current in remove_waiter()")
Signed-off-by: Ji'an Zhou <eilaimemedsnaimel@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Cc: stable@vger.kernel.org
The level_list array is allocated separately right after the parent
struct. The size of the array is already known.
Move level_list to the struct tail as a flexible array member and fold the
two allocations into a single kzalloc_flex().
Signed-off-by: Rosen Penev <rosenp@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Assisted-by: Claude:Opus-4.7
Link: https://patch.msgid.link/20260522231618.41622-1-rosenp@gmail.com
NOHZ_FULL CPUs global timers are guaranteed to be handled by the timekeeper
CPU, which never stops its tick and therefore remains active in the
hierarchy.
But since the introduction of per-capacity hierarchies, this guarantee is
broken because the timekeeper may not belong to the same hierarchy as all
the NOHZ_FULL CPUs.
Fix it with simply turning off capacity awareness when NOHZ_FULL is
running and force a single hierarchy. NOHZ_FULL is not exactly optimized
powerwise anyway.
Fixes: 098cbaad8e ("timers/migration: Split per-capacity hierarchies")
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Link: https://patch.msgid.link/20260519220926.63437-3-frederic@kernel.org
When a top-level migrator is deactivated, either at CPU down hotplug time
or when a CPU is domain isolated, a new migrator is elected among the
available CPUs and woken up to take over the migration duty.
However that election must happen at the scope of a given hierarchy and not
globally, which the introduction of per-capacity hierarchies failed to
handle.
As a result a given hierarchy may end up without migrator to handle global
timers.
Fix it by making sure that the new migrator belongs to the same hierarchy
as the outgoing CPU.
Fixes: 098cbaad8e ("timers/migration: Split per-capacity hierarchies")
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Link: https://patch.msgid.link/20260519220926.63437-2-frederic@kernel.org
The dyntick-idle steal time is currently accounted when the tick restarts
but the stolen idle time is not subtracted from the idle time that was
already accounted. This is to avoid observing the idle time going backward
as the dyntick-idle cputime accessors can't reliably know in advance the
stolen idle time.
In order to maintain a forward progressing idle cputime while subtracting
idle steal time from it, keep track of the previously accounted idle stolen
time and substract it from _later_ idle cputime accounting.
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Tested-by: Shrikanth Hegde <sshegde@linux.ibm.com>
Link: https://patch.msgid.link/20260508131647.43868-16-frederic@kernel.org
The dyntick-idle cputime accounting always assumes that interrupt time
accounting is enabled and consequently stops elapsing the idle time during
dyntick-idle interrupts.
This doesn't mix up well with disabled interrupt time accounting because
then idle interrupts become a cputime blind-spot. Also this feature is
disabled on most configurations and the overhead of pausing dyntick-idle
accounting while in idle interrupts could then be avoided.
Fix the situation with conditionally pausing dyntick-idle accounting during
idle interrupts only iff either native vtime (which does interrupt time
accounting) or generic interrupt time accounting are enabled.
Also make sure that the accumulated interrupt time is not accidentally
substracted from later accounting.
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Tested-by: Shrikanth Hegde <sshegde@linux.ibm.com>
Link: https://patch.msgid.link/20260508131647.43868-15-frederic@kernel.org
The last reason why get_cpu_idle/iowait_time_us() may return -1 now is if
the config doesn't support nohz.
The ad-hoc replacement solution by cpufreq is to compute jiffies minus the
whole busy cputime. Although the intention should provide a coherent low
resolution estimation of the idle and iowait time, the implementation is
buggy because jiffies don't start at 0.
Just provide instead a real get_cpu_[idle|iowait]_time_us() offcase.
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Tested-by: Shrikanth Hegde <sshegde@linux.ibm.com>
Link: https://patch.msgid.link/20260508131647.43868-14-frederic@kernel.org
Fetching the idle cputime is available through a variety of accessors all
over the place depending on the different accounting flavours and needs:
- idle vtime generic accounting can be accessed by kcpustat_field(),
kcpustat_cpu_fetch(), get_idle/iowait_time() and
get_cpu_idle/iowait_time_us()
- dynticks-idle accounting can only be accessed by get_idle/iowait_time()
or get_cpu_idle/iowait_time_us()
- CONFIG_NO_HZ_COMMON=n idle accounting can be accessed by kcpustat_field()
kcpustat_cpu_fetch(), or get_idle/iowait_time() but not by
get_cpu_idle/iowait_time_us()
Moreover get_idle/iowait_time() relies on get_cpu_idle/iowait_time_us()
with a non-sensical conversion to microseconds and back to nanoseconds on
the way.
Start consolidating the APIs with removing get_idle/iowait_time() and make
kcpustat_field() and kcpustat_cpu_fetch() work for all cases.
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Tested-by: Shrikanth Hegde <sshegde@linux.ibm.com>
Link: https://patch.msgid.link/20260508131647.43868-13-frederic@kernel.org
There is no real point in switching to dyntick-idle cputime accounting mode
if the tick is not actually stopped. This just adds overhead, notably
fetching the GTOD, on each idle exit and each idle IRQ entry for no reason
during short idle trips.
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Tested-by: Shrikanth Hegde <sshegde@linux.ibm.com>
Link: https://patch.msgid.link/20260508131647.43868-12-frederic@kernel.org
Although the dynticks-idle cputime accounting is necessarily tied to the
tick subsystem, the actual related accounting code has no business residing
there and should be part of the scheduler cputime code.
Move away the relevant pieces and state machine to where they belong.
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Tested-by: Shrikanth Hegde <sshegde@linux.ibm.com>
Link: https://patch.msgid.link/20260508131647.43868-10-frederic@kernel.org
Even when nohz is not runtime enabled, the dynticks idle cputime accounting
can run and the common idle cputime accessors are still relevant.
Remove the nohz disabled special case accordingly.
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Tested-by: Shrikanth Hegde <sshegde@linux.ibm.com>
Link: https://patch.msgid.link/20260508131647.43868-9-frederic@kernel.org
The non-vtime dynticks-idle cputime accounting is a big mess that
accumulates within two concurrent statistics, each having their own
shortcomings:
* The accounting for online CPUs which is based on the delta between
tick_nohz_start_idle() and tick_nohz_stop_idle().
Pros:
- Works when the tick is off
- Has nsecs granularity
Cons:
- Account idle steal time but doesn't substract it from idle
cputime.
- Assumes CONFIG_IRQ_TIME_ACCOUNTING by not accounting IRQs but
the IRQ time is simply ignored when
CONFIG_IRQ_TIME_ACCOUNTING=n
- The windows between 1) idle task scheduling and the first call
to tick_nohz_start_idle() and 2) idle task between the last
tick_nohz_stop_idle() and the rest of the idle time are
blindspots wrt. cputime accounting (though mostly insignificant
amount)
- Relies on private fields outside of kernel stats, with specific
accessors.
* The accounting for offline CPUs which is based on ticks and the
jiffies delta during which the tick was stopped.
Pros:
- Handles steal time correctly
- Handle CONFIG_IRQ_TIME_ACCOUNTING=y and
CONFIG_IRQ_TIME_ACCOUNTING=n correctly.
- Handles the whole idle task
- Accounts directly to kernel stats, without midlayer accumulator.
Cons:
- Doesn't elapse when the tick is off, which doesn't make it
suitable for online CPUs.
- Has TICK_NSEC granularity (jiffies)
- Needs to track the dyntick-idle ticks that were accounted and
substract them from the total jiffies time spent while the tick
was stopped. This is an ugly workaround.
Having two different accounting for a single context is not the only
problem: since those accountings are of different natures, it is
possible to observe the global idle time going backward after a CPU goes
offline.
Clean up the situation with introducing a hybrid approach that stays
coherent and works for both online and offline CPUs:
* Tick based or native vtime accounting operate before the idle loop
is entered and resume once the idle loop prepares to exit.
* When the idle loop starts, switch to dynticks-idle accounting as is
done currently, except that the statistics accumulate directly to the
relevant kernel stat fields.
* Private dyntick cputime accounting fields are removed.
* Works on both online and offline case.
Further improvement will include:
* Only switch to dynticks-idle cputime accounting when the tick actually
goes in dynticks mode.
* Handle CONFIG_IRQ_TIME_ACCOUNTING=n correctly such that the
dynticks-idle accounting still elapses while on IRQs.
* Correctly substract idle steal cputime from idle time
Reported-by: Xin Zhao <jackzxcui1989@163.com>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Tested-by: Shrikanth Hegde <sshegde@linux.ibm.com>
Link: https://patch.msgid.link/20260508131647.43868-8-frederic@kernel.org
Currently whether generic vtime is running or not, the idle cputime is
fetched from the nohz accounting.
However generic vtime already does its own idle cputime accounting. Only
the kernel stat accessors are not plugged to support it.
Read the idle generic vtime cputime when it's running, this will allow to
later more clearly split nohz and vtime cputime accounting.
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Tested-by: Shrikanth Hegde <sshegde@linux.ibm.com>
Link: https://patch.msgid.link/20260508131647.43868-5-frederic@kernel.org
The first parameter to kcpustat_field() is a pointer to the cpu kcpustat to
be fetched from. This parameter is error prone because a copy to a kcpustat
could be passed by accident instead of the original one. Also the kcpustat
structure can already be retrieved with the help of the mandatory CPU
argument.
Remove the needless parameter.
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Tested-by: Shrikanth Hegde <sshegde@linux.ibm.com>
Reviewed-by: Shrikanth Hegde <sshegde@linux.ibm.com>
Link: https://patch.msgid.link/20260508131647.43868-4-frederic@kernel.org
Offline handling happens from within the inner idle loop, after the
beginning of dyntick cputime accounting, nohz idle load balancing and
TIF_NEED_RESCHED polling.
This is not necessary and even buggy because:
* There is no dyntick handling to do. And calling tick_nohz_idle_enter()
messes up with the struct tick_sched reset that was performed on
tick_sched_timer_dying().
* There is no nohz idle balancing to do.
* Polling on TIF_RESCHED is irrelevant at this stage, there are no more
tasks allowed to run.
* No need to check if need_resched() before offline handling since
stop_machine is done and all per-cpu kthread should be done with
their job.
Therefore move the offline handling at the beginning of the idle loop.
This will also ease the idle cputime unification later by not elapsing
idle time while offline through the call to:
tick_nohz_idle_enter() -> tick_nohz_start_idle()
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Tested-by: Shrikanth Hegde <sshegde@linux.ibm.com>
Reviewed-by: Rafael J. Wysocki (Intel) <rafael@kernel.org>
Reviewed-by: Shrikanth Hegde <sshegde@linux.ibm.com>
Link: https://patch.msgid.link/20260508131647.43868-3-frederic@kernel.org
When the nohz idle time is fetched, the current clock timestamp is taken
outside the seqcount, which can result in a race as reported by Sashiko:
get_cpu_sleep_time_us() tick_nohz_start_idle()
----------------------- ---------------------
now = ktime_get()
write_seqcount_begin(idle_sleeptime_seq);
idle_entrytime = ktime_get()
tick_sched_flag_set(ts, TS_FLAG_IDLE_ACTIVE);
write_seqcount_end(&ts->idle_sleeptime_seq);
read_seqcount_begin(idle_sleeptime_seq)
delta = now - idle_entrytime);
//!! But now < idle_entrytime
idle = *sleeptime + delta;
read_seqcount_retry(&ts->idle_sleeptime_seq, seq)
Here the read side fetches the timestamp before the write side and its
update. As a result the time delta computed on the read side is negative
(ktime_t is signed) and breaks the cputime monotonicity guarantee.
This could possibly be fixed with reading the current clock timestamp
inside the seqcount but the reader overhead might then increase. Also
simply checking that the current timestamp is above the idle entry time
is enough to prevent any issue of the like.
Fixes: 620a30fa0b ("timers/nohz: Protect idle/iowait sleep time under seqcount")
Reported-by: Sashiko
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Link: https://patch.msgid.link/20260508131647.43868-2-frederic@kernel.org
The validation check uses '>' instead of '>=' when comparing tv_usec
against USEC_PER_SEC, allowing the value 1000000 through. After
conversion to nanoseconds (*= 1000), this produces tv_nsec ==
NSEC_PER_SEC, violating the timespec invariant that tv_nsec must be
less than NSEC_PER_SEC.
Use '>=' to reject tv_usec values that are not in the valid range of
0 to 999999.
Fixes: 5e0fb1b57b ("y2038: time: avoid timespec usage in settimeofday()")
Signed-off-by: Naveen Kumar Chaudhary <naveen.osdev@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Acked-by: John Stultz <jstultz@google.com>
Link: https://patch.msgid.link/4rikk44zew3s6577dugmx4jyblz7o5c57niuap6ct3td5yfm6w@gh7pcumg7qor
The stub for arch_inlined_clockevent_set_next_coupled() has 'u64 u64
cycles' in its parameter list. Since u64 is a typedef, the compiler
parses the second 'u64' as the parameter name, making 'cycles' an
unused token. Remove the duplicate so the parameter is correctly named.
Fixes: 89f951a1e8 ("clockevents: Provide support for clocksource coupled comparators")
Signed-off-by: Naveen Kumar Chaudhary <naveen.osdev@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Link: https://patch.msgid.link/7tostpvxzdn6tobmyow63a5rweatls5kux3scqp2vzhe7mv6uq@ecr746b4hyhf
timens_ktime_to_host() in compares the current time namespace against
init_time_ns for the fast path. It calls do_timens_ktime_to_host() for the
offset case. Both symbols are needed at link time by any caller of the
inline.
All current callers are builtin, but ntsync can be built as module, which
prevents it from using it.
Export both with EXPORT_SYMBOL_GPL.
Signed-off-by: Maoyi Xie <maoyixie.tju@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Link: https://patch.msgid.link/20260528063311.3300393-2-maoyixie.tju@gmail.com
cgroup_apply_control_disable() defers kill_css_finish() while a css is
still populated, relying on css_update_populated() to fire the deferred
kill once the populated count reaches zero.
This deadlocks when a controller is rebound out of a hierarchy. Mounting
an implicit_on_dfl controller such as perf_event as a v1 hierarchy steals
it off the default hierarchy, and rebind_subsystems() kills its
per-cgroup csses while they are still populated. The migration run in the
same step keeps the old css for a controller no longer in the hierarchy's
mask, so no task is migrated off the dying csses. Their populated count
never reaches zero, the deferred kill_css_finish() never fires, and the
next cgroup_lock_and_drain_offline() hangs forever under cgroup_mutex.
That migration is already a no-op pass over the rebound subtree. Add
cgroup_rebind_ss_mask so find_existing_css_set() resolves the leaving
controllers to the root css. Their tasks are migrated there, the
per-cgroup csses depopulate, and cgroup_apply_control_disable() kills
them synchronously. The deferral stays correct for the rmdir and
controller-disable paths it was meant for.
Fixes: 1dffd95575 ("cgroup: Defer kill_css_finish() in cgroup_apply_control_disable()")
Reported-by: Mark Brown <broonie@kernel.org>
Closes: https://lore.kernel.org/all/41cd159c-54e5-45e0-81df-eaf36a6c028e@sirena.org.uk/
Reported-by: Bert Karwatzki <spasswolf@web.de>
Closes: https://lore.kernel.org/all/4e986b4ed7e16547805d54b6e67d09120bc4d2f2.camel@web.de/
Tested-by: Mark Brown <broonie@kernel.org>
Tested-by: Bert Karwatzki <spasswolf@web.de>
Signed-off-by: Tejun Heo <tj@kernel.org>
When CONFIG_UBSAN_ALIGNMENT is enabled, the stack usage of nocb_gp_wait()
grows above typical warning limits:
In file included from kernel/rcu/tree.c:4930:
kernel/rcu/tree_nocb.h: In function 'rcu_nocb_gp_kthread':
kernel/rcu/tree_nocb.h:866:1: error: the frame size of 1968 bytes is larger than 1280 bytes [-Werror=frame-larger-than=]
Apparently, the problem is passing rcu_data from a 'void *' pointer,
which gcc assumes may be misaligned. When the function is not inlined
into rcu_nocb_gp_kthread(), that is no longer visible to gcc.
Add a 'noinline_for_stack' annotation that leads to skipping a lot of
the alignment sanitizer checks and keeps the stack usage 60% lower here.
Reviewed-by: Kunwu Chan <chentao@kylinos.cn>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Reviewed-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Exclusive maps (aka excl_prog_hash) are meant to be reachable only
from the single program whose hash matches. This is enforced by
check_map_prog_compatibility() when the map is referenced from a
program such as signed BPF loaders.
A bpf_map_elem iterator, however, binds its target map at attach
time in bpf_iter_attach_map() instead of referencing it from the
program, so the exclusivity check is never reached. On top of that,
the iterator exposes the map value as a writable buffer.
Fixes: baefdbdf68 ("bpf: Implement exclusive map creation")
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/r/20260602133052.423725-2-daniel@iogearbox.net
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Add syntax to the parsing of eprobes to be able to typecast a trace event
field that is a pointer to a structure.
Currently, a dereference must be a number, where the user has to figure
out manually the offset of a member of a structure that they want to
dereference.
But for event probes that records a field that happens to be a pointer to
a structure, it cannot dereference these values with BTF naming, but
must use numerical offsets.
For example, to find out what device a sk_buff is pointing to in the
net_dev_xmit trace event, one must first use gdb to find the offsets of the
members of the structures:
(gdb) p &((struct sk_buff *)0)->dev
$1 = (struct net_device **) 0x10
(gdb) p &((struct net_device *)0)->name
$2 = (char (*)[16]) 0x118
And then use the raw numbers to dereference:
# echo 'e:xmit net.net_dev_xmit +0x118(+0x10($skbaddr)):string' >> dynamic_events
If BTF is in the kernel, then instead, the skbaddr can be typecast to
sk_buff and use the normal dereference logic.
# echo 'e:xmit net.net_dev_xmit (sk_buff)skbaddr->dev->name:string' >> dynamic_events
# echo 1 > events/eprobes/xmit/enable
# cat trace
[..]
sshd-session-1022 [000] b..2. 860.249343: xmit: (net.net_dev_xmit) arg1="enp7s0"
sshd-session-1022 [000] b..2. 860.250061: xmit: (net.net_dev_xmit) arg1="enp7s0"
sshd-session-1022 [000] b..2. 860.250142: xmit: (net.net_dev_xmit) arg1="enp7s0"
sshd-session-1022 [000] b..2. 860.263553: xmit: (net.net_dev_xmit) arg1="enp7s0"
sshd-session-1022 [000] b..2. 860.283820: xmit: (net.net_dev_xmit) arg1="enp7s0"
sshd-session-1022 [000] b..2. 860.302716: xmit: (net.net_dev_xmit) arg1="enp7s0"
sshd-session-1022 [000] b..2. 860.322905: xmit: (net.net_dev_xmit) arg1="enp7s0"
sshd-session-1022 [000] b..2. 860.342828: xmit: (net.net_dev_xmit) arg1="enp7s0"
sshd-session-1022 [000] b..2. 860.362268: xmit: (net.net_dev_xmit) arg1="enp7s0"
sshd-session-1022 [000] b..2. 860.382335: xmit: (net.net_dev_xmit) arg1="enp7s0"
sshd-session-1022 [000] b..2. 860.400856: xmit: (net.net_dev_xmit) arg1="enp7s0"
sshd-session-1022 [000] b..2. 860.419893: xmit: (net.net_dev_xmit) arg1="enp7s0"
The syntax is simply: (STRUCT)(FIELD)->MEMBER[->MEMBER..]
Also add comments around the #else and #endif of #ifdef CONFIG_PROBE_EVENTS_BTF_ARGS
to know what they are for.
Link: https://lore.kernel.org/all/20260601130746.2139d926@gandalf.local.home/
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
assign_cfs_rq_runtime() during update_curr() sets the resched indicator
and relies on check_cfs_rq_runtime() during pick_next_task() /
put_prev_entity() to throttle the hierarchy once current task is
preempted / blocks.
Per-task throttle, on the other hand, uses throttle_cfs_rq() to simply
propagate the throttle signals, and then relies on task work to
individually throttle the runnable tasks on their way out to the
userspace.
Remove check_cfs_rq_runtime() and unify throttling into
account_cfs_rq_runtime() which only sets the cfs_rq->throttled,
cfs_rq->throttle_count indicators via throttle_cfs_rq() and optionally
adds the task work to the current task (donor) it is on the throttled
hierarchy.
throttle_cfs_rq() requests for sched_cfs_bandwidth_slice() worth of
bandwidth for the current hierarchy that enable it to continue running
uninterrupted when selected. For the rest, it requests a bare minimum of
"1" to ensure some bandwidth is available and pass the
"runtime_remaining > 0" checks once selected.
For SCHED_PROXY_EXEC, a mutex holder cannot exit to userspace without
dropping it first and the mutex_unlock() ensures proxy is stopped before
the mutex handoff which preserves the current semantics for running a
throttled task until it exits to the userspace even if it acts as a
donor.
[ prateek: rebased on tip, comments, commit message. ]
Reviewed-By: Benjamin Segall <bsegall@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: K Prateek Nayak <kprateek.nayak@amd.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Aaron Lu <ziqianlu@bytedance.com>
Link: https://patch.msgid.link/20260602071005.11942-1-kprateek.nayak@amd.com
An update_curr() during the enqueue of throttled task will start
throttling the hierarchy from subsequent commit. This can lead to
tg_throttle_down() seeing non-empty throttled_limbo_list for the cfs_rq
attaching the task from throttled_limbo_list one by one. For example:
R
|
A
/ \
*B C
|
rq->curr
*B is throttled with tasks on hte limbo list. When the tasks are
unthrottled via tg_unthrottle_up() and entity of group B is placed onto
A, update_curr() is called to catch up the vruntime and it may throttle
group A causing the subsequent tg_throttle_down() to see the pending
task's on B's limbo list.
tg_unthrottle_up()
/* --cfs_rq->throttle_count == 0 */
list_for_each_entry_safe(p, cfs_rq->throttled_limbo_list)
enqueue_task_fair()
enqueue_entity(se /* B->se */)
update_curr(cfs_rq /* A->gcfs_rq */)
account_cfs_rq_runtime(cfs_rq)
throttle_cfs_rq(cfs_rq /* A->gcfs_rq */ )
tg_throttle_down()
/* Reaches B->cfs_rq with throttle_count == 0 */
!!! !list_empty(&cfs_rq->throttled_limbo_list)) !!!
Move the tasks from throttled_limbo_list onto a local list before
starting the unthrottle to prevent the splat described above. If the
hierarchy is throttled again in middle of an unthrottle, put the pending
tasks back onto the limbo list to prevent running them unnecessarily.
Signed-off-by: K Prateek Nayak <kprateek.nayak@amd.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Benjamin Segall <bsegall@google.com>
Tested-by: Aaron Lu <ziqianlu@bytedance.com>
Link: https://patch.msgid.link/20260602052531.11450-2-kprateek.nayak@amd.com
Subsequent commits will allow update_curr() to throttle the hierarchy
when the runtime accounting exceeds allocated quota. Call update_curr()
before the unthrottle event, and in tg_unthrottle_up() to catch up on
any remaining runtime and stabilize the "runtime_remaining" and
"throttle_count" for that cfs_rq.
Doing an update_curr() early ensures the cfs_rq is not throttled right
back up again when the unthrottle is in progress.
Since all callers of unthrottle_cfs_rq(), except two, already update the
rq_clock and call rq_clock_start_loop_update(), move the
update_rq_clock() from unthrottle_cfs_rq() to the callers that don't
update the rq_clock.
Signed-off-by: K Prateek Nayak <kprateek.nayak@amd.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Benjamin Segall <bsegall@google.com>
Tested-by: Aaron Lu <ziqianlu@bytedance.com>
Link: https://patch.msgid.link/20260602052531.11450-1-kprateek.nayak@amd.com
When distribute_cfs_runtime() encounters a local cfs_rq, it adds it to a
local list and unthrottles it at the end, when it is done unthrottling
other cfs_rq(s) on cfs_b->throttled_cfs_rq until the bandwidth runs out.
Instead of using a local list, reuse the local CPU's
rq->throttled_csd_list and the __cfsb_csd_unthrottle() path for
unthrottle.
If this is the first cfs_rq to be queued on the "throttled_csd_list", it
prevents the need for a remote CPUs to interrupt this local CPU if they
themselves are performing async unthrottle.
If this is not the first cfs_rq on the list, there is an async unthrottle
operation pending on this local CPU and the unthrottle can be batched
together.
No functional changes intended.
Signed-off-by: K Prateek Nayak <kprateek.nayak@amd.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Benjamin Segall <bsegall@google.com>
Tested-by: Aaron Lu <ziqianlu@bytedance.com>
Link: https://patch.msgid.link/20260602050005.11160-3-kprateek.nayak@amd.com
Routine conversion of rcu_read_lock(), spin_lock*, and rq_lock usage
within the cfs bandwidth controller to use class guards.
Only notable changes are:
- Checking for "cfs_rq->runtime_remaining <= 0" instead of the inverse
to spot a throttle and break early. This also saves the need
for extra indentation in the unthrottle case.
- Reordering of list_del_rcu() against throttled_clock indicator update
in unthrottle_cfs_rq(). Both are done with "cfs_b->lock" held after
the "cfs_rq->throttled" is cleared which make the reordering safe
against concurrent list modifications.
No functional changes intended.
Signed-off-by: K Prateek Nayak <kprateek.nayak@amd.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Ben Segall <bsegall@google.com>
Tested-by: Aaron Lu <ziqianlu@bytedance.com>
Link: https://patch.msgid.link/20260602050005.11160-2-kprateek.nayak@amd.com
To remove the cfs_rq pointer array in task_group, allocate the combined
cfs_rq and sched_entity using the per-cpu allocator.
This patch implements the following:
- Changes task_group->cfs_rq from 'struct cfs_rq **' to
'struct cfs_rq __percpu *'.
- Updates memory allocation in alloc_fair_sched_group() and
free_fair_sched_group() to use alloc_percpu() and free_percpu()
respectively.
- Uses the inline accessor tg_cfs_rq(tg, cpu) with per_cpu_ptr() to retrieve
the pointer to cfs_rq for the given task group and CPU.
- Replaces direct accesses tg->cfs_rq[cpu] with calls to the new tg_cfs_rq(tg,
cpu) helper.
- Handles the root_task_group: since struct rq is already a per-cpu variable
(runqueues), its embedded cfs_rq (rq->cfs) is also per-cpu. Therefore, we
assign root_task_group.cfs_rq = &runqueues.cfs.
- Cleanup the code in initializing the root task group.
This change places each CPU's cfs_rq and sched_entity in its local per-cpu
memory area to remove the per-task_group pointer arrays.
Signed-off-by: Zecheng Li <zecheng@google.com>
Signed-off-by: Zecheng Li <zli94@ncsu.edu>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: K Prateek Nayak <kprateek.nayak@amd.com>
Reviewed-by: Josh Don <joshdon@google.com>
Link: https://patch.msgid.link/20260522141623.600235-4-zli94@ncsu.edu
Now that struct sched_entity is co-located with struct cfs_rq for non-root task
groups, the task_group->se pointer array is redundant. The associated
sched_entity can be loaded directly from the cfs_rq.
This patch performs the access conversion with the helpers:
- is_root_task_group(tg): checks if a task group is the root task group. It
compares the task group's address with the global root_task_group variable.
- tg_se(tg, cpu): retrieves the cfs_rq and returns the address of the
co-located se. This function checks if tg is the root task group to ensure
behaving the same of previous tg->se[cpu]. Replaces all accesses that use
the tg->se[cpu] pointer array with calls to the new tg_se(tg, cpu) accessor.
- cfs_rq_se(cfs_rq): simplifies access paths like cfs_rq->tg->se[...] to use
the co-located sched_entity. This function also checks if tg is the root
task group to ensure same behavior.
Since tg_se is not in very hot code paths, and the branch is a register
comparison with an immediate value (`&root_task_group`), the performance impact
is expected to be negligible.
Signed-off-by: Zecheng Li <zecheng@google.com>
Signed-off-by: Zecheng Li <zli94@ncsu.edu>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: K Prateek Nayak <kprateek.nayak@amd.com>
Reviewed-by: Josh Don <joshdon@google.com>
Link: https://patch.msgid.link/20260522141623.600235-3-zli94@ncsu.edu
Improve data locality and reduce pointer chasing by allocating struct
cfs_rq and struct sched_entity together for non-root task groups. This
is achieved by introducing a new combined struct cfs_tg_state that
holds both objects in a single allocation.
This patch:
- Introduces struct cfs_tg_state that embeds cfs_rq, sched_entity, and
sched_statistics together in a single structure.
- Updates __schedstats_from_se() in stats.h to use cfs_tg_state for accessing
sched_statistics from a group sched_entity.
- Modifies alloc_fair_sched_group() and free_fair_sched_group() to allocate
and free the new struct as a single unit.
- Modifies the per-CPU pointers in task_group->se and task_group->cfs_rq to
point to the members in the new combined structure.
Signed-off-by: Zecheng Li <zecheng@google.com>
Signed-off-by: Zecheng Li <zli94@ncsu.edu>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: K Prateek Nayak <kprateek.nayak@amd.com>
Reviewed-by: Josh Don <joshdon@google.com>
Link: https://patch.msgid.link/20260522141623.600235-2-zli94@ncsu.edu
Commit ed4fb6d7ef ("hrtimer: Use and report correct timerslack values
for realtime tasks") sets timer_slack_ns to 0 for RT tasks in
__setscheduler_params(). However, when an RT task with SCHED_RESET_ON_FORK
creates child threads, the children inherit timer_slack_ns=0 from the
parent. sched_fork() resets the child's policy to SCHED_NORMAL but does
not restore timer_slack_ns, leaving the child permanently running with
zero slack.
Fix this by restoring timer_slack_ns from default_timer_slack_ns in
sched_fork() when resetting from RT/DL to NORMAL policy, matching the
existing behavior in __setscheduler_params().
Note: this fix alone requires a correct default_timer_slack_ns to be
effective. See the following patch for that fix.
Fixes: ed4fb6d7ef ("hrtimer: Use and report correct timerslack values for realtime tasks")
Reported-by: Qiaoting.Lin <linqiaoting@xiaomi.com>
Signed-off-by: Guanyou.Chen <chenguanyou@xiaomi.com>
Signed-off-by: Chunhui.Li <chunhui.li@mediatek.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260522131000.1664983-2-chenguanyou@xiaomi.com
Now that the proxy path uses ->is_blocked, use the '->is_blocked &&
!->blocked_on' state instead of PROXY_WAKING. Notably, this is where a
blocked_on relation is broken but the donor task might still need a return
migration.
Signed-off-by: K Prateek Nayak <kprateek.nayak@amd.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260526113322.596522894%40infradead.org
Rather than gate the proxy paths with p->blocked_on, use p->is_blocked.
This opens up the state: '->is_blocked && !->blocked_on' for future use.
Notably, only proxy and delayed tasks can be ->on_rq && ->is_blocked, and it is
guaranteed that sched_class::pick_task() will never return a delayed task.
Therefore any task returned from pick_next_task() that has ->is_blocked set,
must be a proxy task.
Suggested-by: K Prateek Nayak <kprateek.nayak@amd.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260526113322.477954312%40infradead.org
Current code will 'unconditionally' return migrate on PROXY_WAKING, even if the
task is (still) on the original CPU.
Check task_cpu(p) against p->waking_cpu, which per proxy_set_task_cpu()
preserves the original CPU the task was on. If they do not mis-match, there is
no need to go through the more expensive wakeup path.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260527082916.GP3126523%40noisy.programming.kicks-ass.net
Upon entry to try_to_block_task(), p->is_blocked should be false. After all,
the prior wakeup would have made it so per ttwu_do_wakeup().
Ensure this is the case, rather than clearing it in the path that doesn't set
it.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: John Stultz <jstultz@google.com>
Link: https://patch.msgid.link/20260526113322.364017314%40infradead.org
The reason for the clause in try_to_wake_up() is, per its comment, that
find_proxy_task()'s proxy_deactivate() is not always called with a cleared
p->blocked_on.
However, that seems silly and easily cured. Make sure to always call
proxy_deactivate() with a cleared p->blocked_on such that we might remove this
clause from the common wake-up path.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: John Stultz <jstultz@google.com>
Link: https://patch.msgid.link/20260526113322.244729903%40infradead.org
Add link to the task this task is proxying for, and use it so
the mutex owner can do an intelligent hand-off of the mutex to
the task that the owner is running on behalf.
[jstultz: This patch was split out from larger proxy patch]
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Juri Lelli <juri.lelli@redhat.com>
Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>
Signed-off-by: Connor O'Brien <connoro@google.com>
Signed-off-by: John Stultz <jstultz@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260512025635.2840817-8-jstultz@google.com
Add a new is_blocked flag to the task struct. This flag is set
by try_to_block_task() and cleared by ttwu_do_wakeup() and
tracks if the task is blocked.
Traditionally this would mirror !p->on_rq, however due things
like DELAY_DEQUEUE and PROXY_EXEC, this can diverge, so its
useful to manage separately.
Additionally with this, we might be able to get rid of the
p->se.sched_delayed (ab)use in the core code (eventually).
Taken whole cloth from Peter's email:
https://lore.kernel.org/lkml/20260501132143.GC1026330@noisy.programming.kicks-ass.net/
With a few additional p->is_blocked = 0 in a few cases where
we return current if blocked_on gets zeroed or there is
no owner. This may hint that these current special cases
might be dropped eventually.
This change also helps resolve wait-queue stalls seen with
proxy-execution. See previous patch attempts for details:
https://lore.kernel.org/lkml/20260430215103.2978955-2-jstultz@google.com/
Reported-by: Vineeth Pillai <vineethrp@google.com>
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: John Stultz <jstultz@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260512025635.2840817-7-jstultz@google.com
This patch adds logic so try_to_wake_up() will notice if we are
waking a task where blocked_on == PROXY_WAKING, and if necessary
dequeue the task so the wakeup will naturally return-migrate the
donor task back to a cpu it can run on.
This helps performance as we do the dequeue and wakeup under the
locks normally taken in the try_to_wake_up() and avoids having
to do proxy_force_return() from __schedule(), which has to
re-take similar locks and then force a pick again loop.
This was split out from the larger proxy patch, and
significantly reworked.
Credits for the original patch go to:
Peter Zijlstra (Intel) <peterz@infradead.org>
Juri Lelli <juri.lelli@redhat.com>
Valentin Schneider <valentin.schneider@arm.com>
Connor O'Brien <connoro@google.com>
Signed-off-by: John Stultz <jstultz@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260512025635.2840817-6-jstultz@google.com
Pull most of the logic out of try_to_block_task() and put it
into block_task() directly, so that we can call block_task() and
not have to worry about the failing cases in try_to_block_task()
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: John Stultz <jstultz@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260512025635.2840817-5-jstultz@google.com
The DL scheduler keeps the current task in the rbtree, since
the deadline value isn't usually chagned while the task is
runnable.
This results in set_next_task() and put_prev_task() being
simpler, but unfortunately this causes complexity elsewhere.
Specifically when update_curr_dl() updates the deadline, it has
to dequeue and then enqueue the task.
From put_prev_task_dl(), we first call update_curr_dl(), and
then call enqueue_pushable_dl_task().
However, with Proxy Exec this goes awry. Since when a mutex is
released, we might wake the waiting rq->donor. This will cause
put_prev_task() to be called on the donor to take it off the
cpu for return migration.
At that point, from put_prev_task_dl() the update_curr_dl()
logic will dequeue & enqueue the task, and the enqueue function
will call enqueue_pushable_dl_task() (since the task_current()
check won't prevent it). Then back up the callstack in
put_prev_task_dl() we'll end up calling
enqueue_pushable_dl_task() again, tripping the
!RB_EMPTY_NODE(&p->pushable_dl_tasks) warning.
So to avoid this, use Peter's suggested[1] approach, and add a
dl_rq->curr pointer that is set/cleared from set_next_task()/
put_prev_task(), which effectively tracks the rq->donor. We can
then use this to avoid adding the active donor to the pushable
list from enqueue_task_dl().
[1]: https://lore.kernel.org/lkml/20260304095123.GP606826@noisy.programming.kicks-ass.net/
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: John Stultz <jstultz@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260512025635.2840817-4-jstultz@google.com
As part of an improvement to handling pushable deadline tasks,
Peter suggested this cleanup[1], to use helper values for
dl_entity and dl_rq in the enqueue_task_dl() and
put_prev_task_dl() functions. There should be no functional
change from this patch.
To make sure this cleanup change doesn't obscure later logic
changes, I've split it into its own patch.
[1]: https://lore.kernel.org/lkml/20260304095123.GP606826@noisy.programming.kicks-ass.net/
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: John Stultz <jstultz@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260512025635.2840817-3-jstultz@google.com
Historically, the prev value from __schedule() was the rq->curr.
This prev value is passed down through numerous functions, and
used in the class scheduler implementations. The fact that
prev was on_cpu until the end of __schedule(), meant it was
stable across the rq lock drops that the class->balance()
implementations often do.
However, with proxy-exec, the prev passed to functions called
by __schedule() is rq->donor, which may not be the same as
rq->curr and may not be on_cpu, this makes the prev value
potentially unstable across rq lock drops.
A recently found issue with proxy-exec, is when we begin doing
return migration from try_to_wake_up(), its possible we may be
waking up the rq->donor. When we do this, we proxy_resched_idle()
to put_prev_set_next() setting the rq->donor to rq->idle, allowing
the rq->donor to be return migrated and allowed to run.
This however runs into trouble, as on another cpu we might be in
the middle of calling __schedule(). Conceptually the rq lock is
held for the majority of the time, but in calling prev_balance()
its possible the class->balance() handler call may briefly drop the rq lock.
This opens a window for try_to_wake_up() to wake and return migrate the
rq->donor before the class logic reacquires the rq lock.
Unfortunately prev_balance() pass in a prev argument, to which we pass
rq->donor. However this prev value can now become stale and incorrect across a
rq lock drop.
So, to correct this, rework the prev_balance() call so that it does not take a
"prev" argument.
Signed-off-by: John Stultz <jstultz@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260512025635.2840817-2-jstultz@google.com
Vineeth found came up with a test driver that could trip up
workqueue stalls. After fixing one issue this test found,
Vineeth reported the test was still failing.
Greatly simplified, a task that tries to take a mutex already
owned by another task that is sleeping, can hit a edge case in
the mutex_lock_common() case.
If the task fails to get the lock, calls into schedule, but gets
a spurious wakeup, it will find that it is first waiter, and
go into the mutex_optimistic_spin() logic. Though before calling
mutex_optimistic_spin(), we clear task blocked_on state, since
mutex_optimistic_spin() may call schedule() if need_resched() is
set.
After mutex_optimistic_spin() fails, we set blocked_on again,
restart the main mutex loop, try to take the lock and call into
schedule_preempt_disabled().
From there, with proxy-execution, we'll see the task is
blocked_on, follow the chain, see the owner is sleeping and
dequeue the waiting task from the runqueue.
This all sounds fine and reasonable. But what I had missed is
that in mutex_optimistic_spin(), not only do we call schedule()
but we set TASK_RUNNABLE right before doing so.
This is ok for that invocation of schedule(). But when we come
back we re-set the blocked_on we had just cleared, but we do not
re-set the task state to TASK_INTERRUPTIBLE/UNINTERRUPTIBLE.
This means we have a task that is blocked_on & TASK_RUNNABLE,
so when the proxy execution code dequeues the task, we are
in trouble since future wakeups will be shortcut by the
ttwu_state_match() check.
Thus, to avoid this, after mutex_optimistic_spin(), set the task
state back when we set blocked_on.
Many many thanks again to Vineeth for his very useful testing
driver that uncovered this long hidden bug, that I hadn't
tripped in all my testing! Very impressed with the problems he's
uncovered!
Reported-by: Vineeth Pillai <vineethrp@google.com>
Signed-off-by: John Stultz <jstultz@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Vineeth Pillai <vineethrp@google.com>
Link: https://patch.msgid.link/20260430215103.2978955-3-jstultz@google.com
system_time_snapshot::systime provides the same information as
system_time_snapshot::real when the snapshot was taken with
ktime_get_snapshot_id(CLOCK_REALTIME).
Convert the history interpolation over to use 'systime' and 'monoraw' as
'real/raw' are going away once all users are converted.
As a side effect this is the first step to support CLOCK_AUX with
get_device_crosstime_stamp() and the history interpolation.
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Tested-by: David Woodhouse <dwmw@amazon.co.uk>
Tested-by: Arthur Kiyanovski <akiyano@amazon.com>
Reviewed-by: David Woodhouse <dwmw@amazon.co.uk>
Reviewed-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Link: https://patch.msgid.link/20260529195557.024415766@kernel.org
ktime_get_snapshot() provides a snapshot of the underlying clocksource
counter value and the corresponding CLOCK_MONOTONIC_RAW, CLOCK_REALTIME and
CLOCK_BOOTTIME timestamps.
There is no usage of CLOCK_REALTIME and CLOCK_BOOTTIME at the same time and
CLOCK_BOOTTIME support was just added for the ARM64 KVM tracing mechanism,
which needs CLOCK_BOOTTIME and the underlying clocksource counter value.
ktime_get_snapshot() is also not suitable for usage with CLOCK_AUX, but
that's a prerequisite to support PTP hardware timestamping for CLOCK_AUX
steering.
As a first step, rename ktime_get_snapshot() to ktime_get_snapshot_id(),
which now takes a clockid argument to select the clock which needs to be
captured. The result is stored in system_time_snapshot::systime, which will
replace the system_time_snapshot::real/boot members once all usage sites
have been converted.
ktime_get_snapshot() is a simple wrapper which hands in CLOCK_REALTIME as
clockid argument for the conversion period. That means CLOCK_REALTIME is
now captured twice, but that redunancy is only temporary.
As all usage sites of struct system_time_snapshot has to be updated anyway,
rename the 'raw' member to 'monoraw' for clarity.
No functional change vs. current users of ktime_get_snapshot()
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Tested-by: David Woodhouse <dwmw@amazon.co.uk>
Tested-by: Arthur Kiyanovski <akiyano@amazon.com>
Reviewed-by: David Woodhouse <dwmw@amazon.co.uk>
Reviewed-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Link: https://patch.msgid.link/20260529195556.971591633@kernel.org
commit 4f375ade6a ("bpf: Avoid RCU context warning when unpinning
htab with internal structs") moved inode cleanup from ->free_inode()
into ->destroy_inode() to avoid sleeping in RCU context when calling
bpf_any_put(). However this removed the RCU delay on freeing the
inode itself and the cached symlink body (i_link), both of which
can be accessed by RCU pathwalk (pick_link, may_lookup etc.).
This causes a use-after-free when a concurrent unlinkat() drops the
last inode reference and destroy_inode() frees the inode immediately,
while another task is still walking the path in RCU mode and reads
inode->i_opflags (offset +2) inside current_time() -> is_mgtime().
KASAN reports:
BUG: KASAN: slab-use-after-free in is_mgtime include/linux/fs.h:2313
Read of size 2 at addr ffff8880407e4282 (offset +2 = i_opflags)
The rules (per Al Viro):
->destroy_inode() called immediately, can sleep, use for blocking
cleanup e.g. bpf_any_put()
->free_inode() called after RCU grace period, use for freeing
inode and anything RCU-accessible e.g. i_link
Fix: split the two concerns properly:
- keep bpf_any_put() in bpf_destroy_inode() since it is blocking
and needs to run promptly
- introduce bpf_free_inode() to handle kfree(i_link) and
free_inode_nonrcu() with proper RCU delay, preventing the UAF
Fixes: 4f375ade6a ("bpf: Avoid RCU context warning when unpinning htab with internal structs")
Reported-by: syzbot+36e50496c8ac4bcde3f9@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=36e50496c8ac4bcde3f9
Suggested-by: Al Viro <viro@zeniv.linux.org.uk>
Link: https://lore.kernel.org/all/20260423043906.GN3518998@ZenIV/
Link: https://lore.kernel.org/all/20260602002607.110866-1-kartikey406@gmail.com/T/ [v1]
Signed-off-by: Deepanshu Kartikey <kartikey406@gmail.com>
Acked-by: Al Viro <viro@zeniv.linux.org.uk>
Link: https://lore.kernel.org/r/20260602025249.113828-1-kartikey406@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
BPF subprogs currently only return void or scalar values. However,
it is also safe to return arena pointers between subprogs in the same
BPF program: Arena pointers are guaranteed to be safe for both programs
at any point. Expand the verifier to permit returning an arena pointer
to the caller.
The main subprog is still not allowed to return an arena pointer because
arena pointers are internal to the BPF program, and the return values
permitted for each main subprog depend on the program type anyway.
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Emil Tsalapatis <emil@etsalapatis.com>
Link: https://lore.kernel.org/r/20260602004120.17087-4-emil@etsalapatis.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
The BTF parsing logic for function arguments goes through
the arguments' decl tags, but does not go into their type
tags. Add type tag parsing for function arguments.
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Emil Tsalapatis <emil@etsalapatis.com>
Link: https://lore.kernel.org/r/20260602004120.17087-3-emil@etsalapatis.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
The loader verifies map->sha against the metadata hash in its
instructions. map->sha is calculated when BPF_OBJ_GET_INFO_BY_FD is
called on the frozen map.
While the map is frozen, the /signed loader/ must also ensure the map
is exclusive, as, without exclusivity (which a hostile host could just
omit when loading the loader), another BPF program with map access can
mutate the contents afterwards, so the check passes on stale data.
With the extra check as part of the signed loader, it now refuses to
move on with map->sha validation if the host set it up wrongly.
Fixes: fb2b0e2901 ("libbpf: Update light skeleton for signing")
Signed-off-by: KP Singh <kpsingh@kernel.org>
Co-developed-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/r/20260601150248.394863-4-daniel@iogearbox.net
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
bpf_map_get_info_by_fd() is the only caller of the ->map_get_hash
and always invokes it with hash_buf == map->sha and hash_buf_size
of SHA256_DIGEST_SIZE. array_map_get_hash() in turn lets sha256()
write the digest directly into that buffer (map->sha) and then
performs a trailing memcpy(), which evaluates to memcpy(map->sha,
map->sha, 32): a redundant self-copy. The hash_buf_size argument
was never used at all. Simplify this a bit, no functional change.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/r/20260601150248.394863-3-daniel@iogearbox.net
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
An exclusive map (created with excl_prog_hash) is bound to a single
program by hash: check_map_prog_compatibility() refuses to load any
program whose digest does not match map->excl_prog_sha. That check
only runs for maps a program references directly, i.e. its used_maps.
A map reached at runtime through a map-of-maps is never in used_maps,
and bpf_map_meta_equal() does not consider excl_prog_sha, so an
exclusive map can be inserted into a non-exclusive outer map and
then looked up and mutated by an unrelated program, bypassing the
exclusivity guarantee.
For the signed loader this defeats the metadata map exclusivity check
added in the signed loader: the cached map->sha[] is validated against
the signed hash while another program on a hostile host rewrites the
frozen map's contents through the outer map.
Fixes: baefdbdf68 ("bpf: Implement exclusive map creation")
Reported-by: sashiko <sashiko@sashiko.dev>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/r/20260601150248.394863-2-daniel@iogearbox.net
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
When checking whether a referenced dynptr can be overwritten,
destroy_if_dynptr_stack_slot only counted sibling dynptrs in the
current call frame. If a clone sharing the same virtual ref parent
existed in a different frame (e.g., passed to a subprog), it would
not be counted, causing the verifier to incorrectly reject the
overwrite with "cannot overwrite referenced dynptr".
Fix by extracting the counting into dynptr_ref_cnt() which uses
bpf_for_each_reg_in_vstate_mask() to scan dynptr stack slots across
all call frames.
Fixes: 017f5c4ef7 ("bpf: Allow overwriting referenced dynptr when refcnt > 1")
Reported-by: Eduard Zingerman <eddyz87@gmail.com>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Amery Hung <ameryhung@gmail.com>
Link: https://lore.kernel.org/r/20260529014936.2811085-10-ameryhung@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Introduce release_reg() to consolidate the release logic shared by both
helpers and kfuncs: dynptr release, kptr_xchg percpu-to-RCU conversion,
regular reference release, and NULL pass-through. NULL pass-through is
only allowed if the prototype indicates the argument may be null.
Determine release_regno from the function prototype/metadata before
argument checking, rather than discovering it dynamically during
argument processing. For helpers, scan the arg_type array in
check_func_proto() via check_proto_release_reg(). For kfuncs, set
release_regno to BPF_REG_1 in bpf_fetch_kfunc_arg_meta() when
KF_RELEASE is set. In the future when we start adding decl_tag to
kfunc arguments, we can just look at the function prototype instead
of a release_regno.
Extract ref_convert_alloc_rcu_protected() and
invalidate_rcu_protected_refs() to make it more clear what the code is
doing. For ref_convert_alloc_rcu_protected(), it pre-converts
MEM_ALLOC | MEM_PERCPU registers to MEM_RCU (clearing id so they
survive), then calls release_reference() to invalidate the remaining
registers and release the reference state.
Add KF_RELEASE to bpf_dynptr_file_discard() so its release_regno is set
via fetch_kfunc_meta rather than being assigned manually in the dynptr
argument processing. Set arg_type to ARG_PTR_TO_DYNPTR for
KF_ARG_PTR_TO_DYNPTR so that check_func_arg_reg_off() correctly allows
non-zero stack offsets for dynptr release arguments same as helper.
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Amery Hung <ameryhung@gmail.com>
Link: https://lore.kernel.org/r/20260529014936.2811085-9-ameryhung@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Helpers and kfuncs independently tracked referenced object metadata
using standalone id fields in their respective arg_meta structs.
This led to duplicated logic and inconsistent error handling between the
two paths.
Introduce struct ref_obj_desc to consolidate id and parent_id along with
a count of how many arguments carry a reference. Add update_ref_obj() to
populate it from a bpf_reg_state, replacing open-coded assignments in
check_func_arg(), check_kfunc_args(), and process_iter_arg(). Add
validate_ref_obj() to check for ambiguous ref_obj before using it.
For ref_obj releasing helpers and kfuncs, keep checking it before
calling update_ref_obj() for now. A later patch will make these
functions not depending on ref_obj. For other users of ref_obj, move the
checks to the use locations. For helper, this means moving the checks
inside helper_multiple_ref_obj_use() to use locations.
is_acquire_function() is dropped as ref_obj is never used.
Pass ref_obj_desc into process_dynptr_func()/mark_stack_slots_dynptr()
instead of a bare parent_id to make it less confusing.
Drop the selftest introduced in 7ec899ac90 ("selftests/bpf: Negative
test case for ref_obj_id in args") since the verifier no longer
complains about ambiguous ref_obj if it is not used.
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Amery Hung <ameryhung@gmail.com>
Link: https://lore.kernel.org/r/20260529014936.2811085-8-ameryhung@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
unmark_stack_slots_dynptr() already makes sure that CONST_PTR_TO_DYNPTR
cannot be released. process_dynptr_func() also prevents passing
uninitialized dynptr to helpers expecting initialized dynptr. Now that
unmark_stack_slots_dynptr() also reports error returned from
release_reference(), there should be no reason to keep these redundant
checks.
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Amery Hung <ameryhung@gmail.com>
Link: https://lore.kernel.org/r/20260529014936.2811085-7-ameryhung@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Refactor object relationship tracking in the verifier and fix a dynptr
use-after-free bug where file/skb dynptrs are not invalidated when the
parent referenced object is freed.
Add parent_id to bpf_reg_state to precisely track child-parent
relationships. A child object's parent_id points to the parent object's
id. This replaces the PTR_TO_MEM-specific dynptr_id.
Remove ref_obj_id from bpf_reg_state by folding its role into the
existing id field. Previously, id tracked pointer identity for null
checking while ref_obj_id tracked the owning reference for lifetime
management. These are now unified: acquire helpers and kfuncs set id
to the acquired reference id, and release paths use id directly.
Add reg_is_referenced() which checks if a register is referenced by
looking up its id in the reference array. This replaces all former
ref_obj_id checks.
For release_reference(), invalidating an object now also invalidates
all descendants by traversing the object tree. This is done using
stack-based DFS to avoid recursive call chains of release_reference() ->
unmark_stack_slots_dynptr() -> release_reference(). Referenced objects
encountered during tree traversal are reported as leaked references.
Add parent_id to bpf_reference_state to enable hierarchical reference
tracking. When acquiring a reference, a parent_id can be specified to
link the new reference to an existing one (e.g., referenced dynptrs
acquire a reference with parent_id linking to the parent object's
reference).
Pointer casting:
For pointer casting helpers (bpf_sk_fullsock, bpf_tcp_sock), instead of
propagating ref_obj_id, the cast result reuses the same reference id as
the source pointer. Since the cast may return NULL for a non-NULL input,
the NULL case is explored as a separate verifier branch. This allows
releasing any of the original or cast pointers to invalidate all others.
Referenced dynptrs:
When constructing a referenced dynptr, acquire a intermediate reference
with parent_id linking to the parent referenced object. The dynptr and
all clones share the same parent_id (pointing to the intermediate ref)
but get unique ids for independent slice tracking. Releasing a
referenced dynptr releases the parent reference, which in turn
invalidates all clones and their derived slices.
Owning to non-owning reference conversion:
After converting owning to non-owning by clearing id (e.g.,
object(id=1) -> object(id=0)), the verifier releases the reference
state via release_reference_nomark().
Note that the error message "reference has not been acquired before" in
the helper and kfunc release paths is removed. This message was already
unreachable. The verifier only calls release_reference() after
confirming the reference is valid, so the condition could never trigger
in practice.
Fixes: 870c28588a ("bpf: net_sched: Add basic bpf qdisc kfuncs")
Signed-off-by: Amery Hung <ameryhung@gmail.com>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20260529014936.2811085-6-ameryhung@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Assign reg->id when getting referenced kptr from read program context
to be consistent with R0 of KF_ACQUIRE kfunc. skb dynptr will track the
referenced skb in qdisc programs using a new field reg->parent_id in
a later patch.
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Amery Hung <ameryhung@gmail.com>
Link: https://lore.kernel.org/r/20260529014936.2811085-4-ameryhung@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Simplify dynptr checking for helper and kfunc by unifying it. Remember
the initialized dynptr (i.e.,g !(arg_type |= MEM_UNINIT)) pass to a
dynptr kfunc during process_dynptr_func() so that we can easily
retrieve the information for verification later. By saving it in
meta->dynptr, there is no need to call dynptr helpers such as
dynptr_id(), dynptr_ref_obj_id() and dynptr_type() in check_func_arg().
Remove and open code the helpers in process_dynptr_func() when
saving id, ref_obj_id, and type.
Besides, since dynptr ref_obj_id information is now pass around in
meta->bpf_dynptr_desc, drop the check in helper_multiple_ref_obj_use.
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Acked-by: Mykyta Yatsenko <yatsenko@meta.com>
Signed-off-by: Amery Hung <ameryhung@gmail.com>
Link: https://lore.kernel.org/r/20260529014936.2811085-3-ameryhung@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Rename mark_stack_slot_obj_read() as mark_stack_slots_scratched() and
directly call it from functions processing iter, dynptr and irq_flag.
Commit 6762e3a0bc ("bpf: simplify liveness to use (callsite, depth)
keyed func_instances") has removed the dynamic liveness component in
mark_stack_slot_obj_read(). The function effectively only marks stack
slots as scratched and always succeed. Therefore, return void, drop the
unused bpf_reg_state argument and rename it to
mark_stack_slots_scratched() to reflect what it does now.
In addition, to prepare for unifying dynptr handling, dynptr_get_spi()
will be moved out of mark_dynptr_read(). As mark_dynptr_read() would join
mark_iter_read() as a thin wrapper of mark_stack_slots_scratched(), just
open code these helpers.
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Amery Hung <ameryhung@gmail.com>
Link: https://lore.kernel.org/r/20260529014936.2811085-2-ameryhung@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Replace BUG_ON(!mutex_is_locked(&event_mutex)) with
lockdep_assert_held(&event_mutex) in uprobe_buffer_enable() and
uprobe_buffer_disable().
BUG_ON() will crash the kernel. mutex_is_locked() only checks
if any task holds lock,but not the caller task. lockdep_assert_held()
also check current task for lock and no crash on true condition.
Link: https://lore.kernel.org/all/20260521192846.8306-1-yashsuthar983@gmail.com/
Signed-off-by: Yash Suthar <yashsuthar983@gmail.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Store probe entry fetch instructions in the probe_entry_arg
allocation instead of allocating a separate instruction array.
This keeps the entry fetch code tied to the entry argument lifetime while
leaving regular probe_arg instruction arrays separately allocated and
freed.
Assisted-by: Codex:GPT-5.5
Link: https://lore.kernel.org/all/20260520215817.16560-1-rosenp@gmail.com/
Signed-off-by: Rosen Penev <rosenp@gmail.com>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
The ser field in struct luo_session was intended to point to the
serialized data for a session, but it was never actually utilized in the
implementation. All serialization and deserialization logic consistently
uses the pointers maintained in struct luo_session_header.
Remove the dead field to clean up the structure.
Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Reviewed-by: Pratyush Yadav (Google) <pratyush@kernel.org>
Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Link: https://patch.msgid.link/20260527202737.1345192-6-pasha.tatashin@soleen.com
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
In luo_file_unpreserve_files() and luo_file_finish(), reorder
module_put() and xa_erase() to ensure the file handler module remains
pinned while its operations are being accessed.
Specifically, luo_get_id() dereferences fh->ops->get_id, so the module
reference must be held until after xa_erase() (which calls luo_get_id)
completes.
For luo_file_finish(), this requires moving the module_put() call out of
the luo_file_finish_one() helper and into the main loop of
luo_file_finish() itself.
Fixes: 00d0b37237 ("liveupdate: prevent double management of files")
Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Reviewed-by: Pratyush Yadav (Google) <pratyush@kernel.org>
Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Link: https://patch.msgid.link/20260527202737.1345192-5-pasha.tatashin@soleen.com
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
During the reboot() syscall, user processes may still be running
concurrently and attempting to mutate sessions (e.g., creating,
retrieving, or releasing sessions). To prevent this, introduce
luo_session_serialize_rwsem to synchronize mutations with the
serialization process.
All session mutation operations (create, retrieve, release, ioctl) take
the read lock. The serialization process (luo_session_serialize) takes
the write lock and holds it indefinitely on success. This effectively
freezes the LUO session subsystem during the transition to the new
kernel. If serialization fails, the lock is released to allow recovery.
Fixes: 0153094d03 ("liveupdate: luo_session: add sessions support")
Reported-by: Oskar Gerlicz Kowalczuk <oskar@gerlicz.space>
Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Reviewed-by: Pratyush Yadav (Google) <pratyush@kernel.org>
Link: https://patch.msgid.link/20260527202737.1345192-4-pasha.tatashin@soleen.com
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Extend the scope of the rwsem_read lock in luo_session_retrieve() to
overlap with the acquisition of the session mutex. This prevents a
concurrent thread from releasing and freeing the session between the
lookup and the mutex lock.
Fixes: 0153094d03 ("liveupdate: luo_session: add sessions support")
Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Reviewed-by: Pratyush Yadav (Google) <pratyush@kernel.org>
Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Link: https://patch.msgid.link/20260527202737.1345192-3-pasha.tatashin@soleen.com
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
A preserve_context kexec returns to the current kernel, which is
unrelated to live update where the state is passed to the next kernel.
Skip liveupdate_reboot() in this case to avoid serialization and prevent
sessions from being left in a frozen state upon return.
Fixes: db8bed8082 ("kexec: call liveupdate_reboot() before kexec")
Reported-by: Oskar Gerlicz Kowalczuk <oskar@gerlicz.space>
Reviewed-by: Pratyush Yadav (Google) <pratyush@kernel.org>
Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Link: https://patch.msgid.link/20260527202737.1345192-2-pasha.tatashin@soleen.com
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
When using scratch_scale, the scratch sizes are rounded up to
CMA_MIN_ALIGNMENT_BYTES since they will be released as MIGRATE_CMA. This
is not done when using fixed scratch sizes via command line. This can
result in user specifying a size which is not aligned, and thus kernel
releasing a pageblock that is only partially scratch.
Do the rounding up for both cases in scratch_size_update().
Fixes: 3dc92c3114 ("kexec: add Kexec HandOver (KHO) generation helpers")
Cc: stable@kernel.org
Signed-off-by: Pratyush Yadav (Google) <pratyush@kernel.org>
Link: https://patch.msgid.link/20260519160554.2713361-1-pratyush@kernel.org
Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
While the liveupdate= parameter is documented in kernel-parameters.txt,
it is not listed in LUO's user facing documentation. This can make it
hard for users to figure out how to enable the subsystem, since enabling
just the config isn't enough.
Note the need for the kernel parameter in LUO core documentation, which
gets exported to Documentation/core-api/liveupdate.rst.
Suggested-by: Luca Boccassi <luca.boccassi@gmail.com>
Signed-off-by: Pratyush Yadav (Google) <pratyush@kernel.org>
Acked-by: Luca Boccassi <luca.boccassi@gmail.com>
Link: https://patch.msgid.link/20260519125714.2435640-1-pratyush@kernel.org
Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
The sessions ioctls are not applicable to all session types. PRESERVE_FD
is only applicable to outgoing sessions. RETRIEVE_FD and FINISH are only
valid for incoming session. Calling a incoming ioctl on an outgoing
session is invalid and can cause file handlers to run into unexpected
errors.
For example, a user can create a (outgoing) session, preserve a memfd,
and then immediately do a retrieve without doing a kexec in between.
This would result in memfd's retrieve handler to run. The handlers
expects to be called from a post-kexec context, and will try to do a
kho_restore_vmalloc() or kho_restore_folio() to try and restore memory.
KHO catches this (thanks to KHO_PAGE_MAGIC) and returns an error, but
since this is considered an internal error and KHO throws out a bunch of
WARN()s.
Associate a type with each ioctl op and validate the type in
luo_session_ioctl() before dispatching the ioctl handler to make sure
the op is being called for the right session type.
Fixes: 16cec0d265 ("liveupdate: luo_session: add ioctls for file preservation")
Cc: stable@vger.kernel.org
Signed-off-by: Pratyush Yadav (Google) <pratyush@kernel.org>
Link: https://patch.msgid.link/20260519122428.2378446-1-pratyush@kernel.org
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
If security_bpf_prog_load() fails there is no need to call into
security_bpf_prog_free() as the LSM will handle the cleanup of any partial
LSM state before returning to the caller with an error. Thankfully this
isn't an issue with any of the existing code as the LSMs which currently
provide BPF hook callback implementations don't allocate any internal
state, but this is something we want to fix for potential future users.
Signed-off-by: Paul Moore <paul@paul-moore.com>
Link: https://lore.kernel.org/r/20260523160025.16363-2-paul@paul-moore.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Global subprogram argument checking derives generic pointer sizes from BTF
and passes the resolved size to check_mem_reg() as a u32. The access-size
validation path then uses a signed int, and stack pointers negate the value
before calling check_helper_mem_access().
This creates a wrap when BTF describes a pointee size larger than S32_MAX.
For example, a global subprogram argument of type:
int (*p)[0x3fffffff]
has a BTF-resolved pointee size of 0xfffffffc bytes. At a call site the
caller can pass a pointer to a 4-byte stack slot at fp-4. The current
PTR_TO_STACK path computes:
size = -(int)mem_size
so 0xfffffffc becomes -4 as a signed int and the negation validates only
a 4-byte stack range. That range is covered by the caller's stack slot,
so the call is accepted.
The callee is then verified independently with R1 as PTR_TO_MEM and
mem_size 0xfffffffc. A small instruction such as:
r0 = *(u32 *)(r1 + 4)
is accepted as being inside that BTF-described memory region. At run time,
however, the actual argument value is still fp-4, so r1 + 4 addresses fp+0,
outside the 4-byte object that the caller provided.
Reject sizes that cannot be represented by the verifier's signed
access-size API before the stack-specific negation. Add a verifier
regression test for the oversized BTF argument.
Fixes: 2cb27158ad ("bpf: poison dead stack slots")
Signed-off-by: Taegu Ha <hataegu0826@gmail.com>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20260528062155.3988156-1-hataegu0826@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
If the persistent ring buffer is detected on boot up to have a corrupted
sub-buffer, that sub-buffer is cleared to zero and its commit value has
the RB_MISSED_EVENTS bit set. That bit is to allow the "trace",
"trace_pipe" and "trace_pipe_raw" files know that events were dropped by
outputting "[LOST EVENTS]".
Only in this case does that bit get set in the writeable portion of the
ring buffer. When events are dropped in the normal ring buffer, that
information is stored in the cpu_buffer descriptor and the
RB_MISSED_EVENTS is set in the buffer page at the time the page is
consumed. It is never set in the writeable portion of the buffer.
Add comments to describe this better as it can be confusing to know when
the RB_MISSED_EVENTS are set in the commit portion of the buffer page.
Link: https://lore.kernel.org/all/20260529001500.14178455a046a5cbc6180861@kernel.org/
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Link: https://patch.msgid.link/20260528223738.41276c0e@fedora
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Increment the incoming FLB refcount in liveupdate_flb_get_incoming() so
that the FLB structure cannot be freed while the caller is actively using
it. Add an additional liveupdate_flb_put_incoming() function so the
caller can explicitly indicate when it is done using the FLB data.
During a Live Update, a subsystem might need to hold onto the incoming
File-Lifecycle-Bound (FLB) data for an extended period, such as during
device enumeration. Incrementing the reference count guarantees that the
data remains valid and accessible until the subsystem releases it,
preventing future use-after-free bugs.
Fixes: cab056f2aa ("liveupdate: luo_flb: introduce File-Lifecycle-Bound global state")
Signed-off-by: David Matlack <dmatlack@google.com>
Reviewed-by: Samiullah Khawaja <skhawaja@google.com>
Reviewed-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Link: https://lore.kernel.org/r/20260423174032.3140399-3-dmatlack@google.com
Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Use refcount_t instead of a raw integer to keep track of references on
incoming and outgoing FLBs. Using refcount_t provides protection from
overflow, underflow, and other issues.
Fixes: cab056f2aa ("liveupdate: luo_flb: introduce File-Lifecycle-Bound global state")
Signed-off-by: David Matlack <dmatlack@google.com>
Reviewed-by: Samiullah Khawaja <skhawaja@google.com>
Reviewed-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Link: https://lore.kernel.org/r/20260423174032.3140399-2-dmatlack@google.com
Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Userspace when requesting a session via the ioctl specifies a name and
gets a FD, but then there is no ioctl to go back the other way and get
the name given a LUO session FD. This is problematic especially when
there is a userspace orchestrator that wants to check what FDs it is
handling for clients without having to do manual string scraping of
procfs, or without procfs at all.
Add a ioctl to simply get the name from an FD.
Signed-off-by: Luca Boccassi <luca.boccassi@gmail.com>
Reviewed-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Reviewed-by: Pratyush Yadav <pratyush@kernel.org>
Link: https://lore.kernel.org/r/20260429212221.814107-4-luca.boccassi@gmail.com
Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
A session name must not be an empty string, and must not exceed the
maximum size define in the uapi header, including null termination.
Fixes: 0153094d03 ("liveupdate: luo_session: add sessions support")
Cc: stable@vger.kernel.org
Signed-off-by: Luca Boccassi <luca.boccassi@gmail.com>
Reviewed-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Reviewed-by: Pratyush Yadav <pratyush@kernel.org>
Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Link: https://lore.kernel.org/r/20260429212221.814107-2-luca.boccassi@gmail.com
Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
When CONFIG_DEFERRED_STRUCT_PAGE_INIT is enabled, struct page
initialization is deferred to parallel kthreads that run later
in the boot process.
During KHO restoration, kho_preserved_memory_reserve() writes metadata
for each preserved memory region. However, if the struct page has not
been initialized, this write targets uninitialized memory, potentially
leading to errors like:
BUG: unable to handle page fault for address: ...
Fix this by introducing kho_get_preserved_page(), which ensures
all struct pages in a preserved region are initialized by calling
init_deferred_page() which is a no-op when the struct page is already
initialized.
Signed-off-by: Evangelos Petrongonas <epetron@amazon.de>
Co-developed-by: Michal Clapinski <mclapinski@google.com>
Signed-off-by: Michal Clapinski <mclapinski@google.com>
Reviewed-by: Pratyush Yadav (Google) <pratyush@kernel.org>
Reviewed-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Link: https://patch.msgid.link/20260423122538.140993-3-mclapinski@google.com
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Currently, if CONFIG_DEFERRED_STRUCT_PAGE_INIT is enabled,
kho_release_scratch() will initialize the struct pages and set migratetype
of KHO scratch. Unless the whole scratch fits below first_deferred_pfn,
some of that will be overwritten either by deferred_init_pages() or
memmap_init_reserved_range().
To fix it, make memmap_init_range(), deferred_init_memmap_chunk() and
__init_page_from_nid() recognize KHO scratch regions and set
migratetype of pageblocks in those regions to MIGRATE_CMA.
Co-developed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Signed-off-by: Michal Clapinski <mclapinski@google.com>
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Reviewed-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Reviewed-by: Pratyush Yadav (Google) <pratyush@kernel.org>
Link: https://patch.msgid.link/20260423122538.140993-2-mclapinski@google.com
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
BPF arena (kernel/bpf/arena.c) is compiled only on MMU && 64BIT, while
SCHED_CLASS_EXT depends on BPF_SYSCALL && BPF_JIT && DEBUG_INFO_BTF with no
64BIT requirement. On a 32-bit arch with a BPF JIT, SCX builds while the
arena helpers are absent, so the cid-form code's unconditional calls to
bpf_prog_arena() and bpf_arena_map_kern_vm_start() fail to link:
build_policy.o: undefined reference to `bpf_prog_arena'
build_policy.o: undefined reference to `bpf_arena_map_kern_vm_start'
Guard the three call sites with the same MMU && 64BIT condition that gates
arena.o. A cid-form scheduler needs a BPF arena, which isn't available on
such builds, so it can't run there regardless. cpu-form schedulers don't
touch the arena and are unaffected.
This is a quick workaround to get past the build errors. A fuller fix may
make the whole cid-form path conditional on the same condition, or drop
32-bit support outright.
Fixes: 0e2819cba9 ("sched_ext: Require an arena for cid-form schedulers")
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202605310454.U9iByL2n-lkp@intel.com/
Closes: https://lore.kernel.org/oe-kbuild-all/202605310926.APXMc0RJ-lkp@intel.com/
Signed-off-by: Tejun Heo <tj@kernel.org>
BPF_PROG_QUERY writes back the 'query.revision' field unconditionally to
userspace. If userspace passes a smaller 'bpf_attr' structure (e.g. 40
bytes, which was the layout before the addition of 'query.revision'),
the kernel performs an out-of-bounds write.
Fix this by propagating the user-provided attribute size 'uattr_size'
down to the cgroup query handlers, and conditionally skipping writing
the revision field to userspace when the provided buffer size is
insufficient.
query.revision in bpf_mprog_query is structurally identical to the
cgroup case: a late tail field, written unconditionally.
But the backward-compat hazard is not the same.
The min-historical-size test is per command, and bpf_mprog_query only
serves attach types that were born with revision in the struct:
- tcx_prog_query -> BPF_TCX_INGRESS/EGRESS
- netkit_prog_query -> BPF_NETKIT_PRIMARY/PEER
tcx, netkit, the revision field, and bpf_mprog_query itself all landed in
the same v6.6 merge window (053c8e1f23 added the mprog query API +
revision; tcx in e420bed025, netkit in 35dfaad718). There has never
been a tcx/netkit BPF_PROG_QUERY userspace that doesn't know about
revision. So for these commands the minimum legitimate struct already
covers offset 56-64 — no old binary can be broken here.
Contrast with cgroup: BPF_PROG_QUERY on cgroup attach types shipped in
2017; revision write-back was bolted on years later (1209339844). That
path has a real population of pre-revision callers.
Fixes: 1209339844 ("bpf: Implement mprog API on top of existing cgroup progs")
Cc: Maciej Żenczykowski <maze@google.com>
Cc: Lorenzo Colitti <lorenzo@google.com>
Signed-off-by: Yuyang Huang <yuyanghuang@google.com>
Link: https://lore.kernel.org/r/20260531075600.4058207-2-yuyanghuang@google.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
* fix order calculation for kho_unpreserve_pages() to make sure sure that
the order calculation in kho_unpreserve_pages() mathes the order
calculation in kho_preserve_pages().
* fix math in calculation of KHO_TREE_MAX_DEPTH to make it work with 16KB
pages.
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Merge tag 'liveupdate-fixes-2026-05-30' of git://git.kernel.org/pub/scm/linux/kernel/git/liveupdate/linux
Pull liveupdate fixes from Mike Rapoport:
"Two kexec handover regression fixes:
- fix order calculation for kho_unpreserve_pages() to make sure sure
that the order calculation in kho_unpreserve_pages() mathes the
order calculation in kho_preserve_pages().
- fix math in calculation of KHO_TREE_MAX_DEPTH to make it work with
16KB pages"
* tag 'liveupdate-fixes-2026-05-30' of git://git.kernel.org/pub/scm/linux/kernel/git/liveupdate/linux:
kho: fix order calculation for kho_unpreserve_pages()
kho: fix KHO_TREE_MAX_DEPTH for non-4KB page sizes
Fix to point the error offset correctly for eprobe argument error.
In the cleanup commit 1b8b0cd754 ("tracing/probes: Move event parameter
fetching code to common parser"), due to incorrect backward compatibility
aimed at conforming to the test specifications, the error location was set
to 0 when a non-existent formal parameter was specified for Eprobe.
However, this should be corrected in both the test and the implementation
to point correct error position.
Link: https://lore.kernel.org/all/177967567399.209006.1451571244515632097.stgit@devnote2/
Fixes: 1b8b0cd754 ("tracing/probes: Move event parameter fetching code to common parser")
Cc: stable@vger.kernel.org
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Reviewed-by: Steven Rostedt <rostedt@goodmis.org>
generate_sched_domains() returns sched-domain masks and optional
attributes that are normally handed to partition_sched_domains(), which
takes ownership of them.
rebuild_sched_domains_locked() has a WARN guard after
generate_sched_domains() and before partition_sched_domains() to avoid
passing offline CPUs into the scheduler domain rebuild path. If that
guard fires, the function currently returns directly without freeing
the generated doms and attr.
Free the generated sched-domain masks and attributes before returning
from the guard failure path.
Signed-off-by: Guopeng Zhang <zhangguopeng@kylinos.cn>
Reviewed-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Currently there are no checks in order to enforce the use of one between
WQ_PERCPU or WQ_UNBOUND.
So act as following:
- if neither of them is present, set WQ_PERCPU
- if both are present, remove WQ_PERCPU
Along with this change, WARN_ONCE(), so that the code still uses both or
neither of them, can be changed.
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>
Currently many users transitioned already to the new introduced workqueue
(system_percpu_wq, system_dfl_wq), but there are new users who still use the
older system_wq and system_unbound_wq.
This change try to push this transition forward, by warning whether the old
workqueues are used.
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>
perf_ftrace_function_unregister() unconditionally calls
unregister_ftrace_function() without checking whether the ftrace_ops
was ever successfully registered. This triggers a WARN_ON in
__unregister_ftrace_function() when the ops doesn't have
FTRACE_OPS_FL_ENABLED set.
This can happen during perf_event_alloc() error cleanup when
perf_trace_destroy() is called via __free_event() on an event whose
ftrace_ops registration failed or was already torn down by
perf_try_init_event()'s err_destroy path.
The call path is:
perf_event_alloc() error cleanup
-> __free_event()
-> event->destroy() [tp_perf_event_destroy]
-> perf_trace_destroy()
-> perf_trace_event_close()
-> TRACE_REG_PERF_CLOSE
-> perf_ftrace_function_unregister()
-> unregister_ftrace_function()
-> __unregister_ftrace_function()
-> WARN_ON(!(ops->flags & FTRACE_OPS_FL_ENABLED))
Fix this by checking FTRACE_OPS_FL_ENABLED before attempting to
unregister. If the ops is not enabled, just free the filter and
return success.
Link: https://patch.msgid.link/20260527111301.2d0d8256@fangorn
Signed-off-by: Rik van Riel <riel@surriel.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
When KCOV runs its boot selftest with whole-kernel instrumentation
enabled, it sets current->kcov_mode to KCOV_MODE_TRACE_PC without
installing a coverage area. Any instrumented code accepted as task-context
coverage in that window dereferences current->kcov_area and crashes.
On ARMv5 Versatile PB with CONFIG_KCOV_SELFTEST=y,
CONFIG_KCOV_INSTRUMENT_ALL=y and CONFIG_IRQSOFF_TRACER=y, boot hits a
NULL pointer fault during the selftest:
kcov: running self test
Internal error: Oops: 5 [#1] ARM
PC is at __sanitizer_cov_trace_pc+0x4c/0x90
Kernel panic - not syncing: Fatal exception
A diagnostic run showed the unwanted coverage comes from the IRQs-off
tracer callbacks reached from ARM IRQ entry before hardirq context is
visible to KCOV:
__sanitizer_cov_trace_pc from tracer_hardirqs_off+0x18/0x1cc
tracer_hardirqs_off from trace_hardirqs_off+0x34/0x54
trace_hardirqs_off from __irq_svc+0x58/0xb0
__irq_svc from kcov_init+0x7c/0xdc
and similarly through tracer_hardirqs_on().
trace_preemptirq.o is already excluded because this tracing path can run
from early interrupt code and produce coverage unrelated to syscall
inputs. Exclude trace_irqsoff.o as well, instead of requiring users to
turn off CONFIG_KCOV_INSTRUMENT_ALL=y, which is the default whole-kernel
KCOV mode.
With the exclusion in place, the same ARMv5 Versatile PB QEMU test boots
through the KCOV selftest and reaches userspace.
Tested on ARMv5 Versatile PB QEMU with CONFIG_KCOV_SELFTEST=y,
CONFIG_KCOV_INSTRUMENT_ALL=y and CONFIG_IRQSOFF_TRACER=y.
Link: https://patch.msgid.link/20260525170428.67211-1-kmehltretter@gmail.com
Assisted-by: Codex:gpt-5
Signed-off-by: Karl Mehltretter <kmehltretter@gmail.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
The field_var_str array was allocated separately via kcalloc() with its
length already known at elt_data allocation time. Convert it to a
flexible array member and fold the two allocations into a single
kzalloc_flex(), reordering hist_trigger_elt_data_alloc() so n_str is
computed and bounds-checked before the struct allocation.
hist_elt_data is only reached through tracing_map_elt::private_data
(a void *), never embedded, so adding a FAM imposes no tail-position
constraint on any enclosing struct.
Added __counted_by for extra runtime analysis.
Link: https://patch.msgid.link/20260522214407.18120-1-rosenp@gmail.com
Assisted-by: Claude:Opus-4.7
Signed-off-by: Rosen Penev <rosenp@gmail.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
None of the calls to trace_array_printk_buf() will do anything
if we don't initialize the buffer on instance creation (unless
some other tracer called it), so do that.
Add an osnoise_print() function to facilitate adding debug prints
(without tainting).
Use trace_array_printk() instead of trace_array_printk_buf(), as we're
only writing to the main buffer (of a non-main instance) anyway -- and
trace_array_printk_buf() skips the check to make sure we're not printing
to the global instance.
Link: https://patch.msgid.link/20260511223035.1475676-1-crwood@redhat.com
Signed-off-by: Crystal Wood <crwood@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
update_tg_load_avg() is called once per leaf cfs_rq from the
__update_blocked_fair() walk that runs inside the NOHZ idle-balance
softirq, and again from update_load_avg() with UPDATE_TG. Its first
operation after the trivial early-outs is unconditionally:
now = sched_clock_cpu(cpu_of(rq_of(cfs_rq)));
if (now - cfs_rq->last_update_tg_load_avg < NSEC_PER_MSEC)
return;
Jakub ran into a system where nohz_idle_balance() was taking 75%
of a CPU (which is handling network traffic and doing many irq_exit_cpu
calls), with 35% of that CPU spent in update_load_avg, and 17% of the
CPU in sched_clock_cpu(), reading the TSC.
In a quick synthetic test, it looks like this patch reduces the
CPU use of sched_balance_update_blocked_averages by about 20%.
Switch the rate-limit to read rq_clock(rq_of(cfs_rq)) instead.
This eliminates the rdtsc, and uses a fairly fresh timestamp,
because all callers of update_tg_load_avg() and clear_tg_load_avg()
hold rq->lock and have called update_rq_clock(rq) within microseconds:
caller pre-state
__update_blocked_fair encloser did update_rq_clock(rq)
update_load_avg's three UPDATE_TG sites under rq->lock after enqueue/dequeue/update_curr
attach_/detach_entity_cfs_rq preceded by update_load_avg(...)
clear_tg_load_avg via offline path rq_clock_start_loop_update(rq) upfront
so rq->clock is fresh at every call. Since cfs_rqs are per-CPU
per-task_group, cfs_rq->last_update_tg_load_avg is always compared
against the same rq's clock; no cross-rq drift.
Signed-off-by: Rik van Riel <riel@surriel.com>
Assisted-by: Claude (Anthropic)
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://patch.msgid.link/20260527110250.6a91718d@fangorn
Commit cd959a3562 ("sched_ext: Add a DL server for sched_ext tasks")
introduced an ext_server deadline server to protect sched_ext tasks from
fair/RT starvation, mirroring the existing fair_server.
Currently, both servers reserve their 50ms/1000ms bandwidth at boot,
regardless of whether a BPF scheduler is loaded. Unused bandwidth is
still reclaimed at runtime by other classes, but the static reservation
prevents the RT class from implicitly using that headroom when one of
the two classes is guaranteed to be empty.
A sysadmin can work around this by writing
/sys/kernel/debug/sched/{fair,ext}_server/cpu*/runtime, but that
requires manual action and not all systems expose debugfs.
A better approach is to make server bandwidth reservations dynamic: only
the scheduling policy that is currently active should register its
reservation, while the inactive one should not artificially hold
capacity (keeping both reservations only when the BPF scheduler is
running in partial mode):
+---------------------------------------------+-------------+------------+
| BPF scheduler state | fair server | ext server |
+---------------------------------------------+-------------+------------+
| not loaded (default boot) | reserved | none |
| loaded full mode (!SCX_OPS_SWITCH_PARTIAL) | none | reserved |
| loaded partial mode (SCX_OPS_SWITCH_PARTIAL)| reserved | reserved |
+---------------------------------------------+-------------+------------+
To achieve this, introduce an "attached/detached" state for each
deadline server, so the kernel can decide whether a server's bandwidth
should be accounted in global bandwidth tracking.
At boot, the system starts with only the fair server contributing to
bandwidth accounting. When a BPF scheduler is enabled, the ext server is
attached and may replace or complement the fair server depending on
whether full or partial mode is used. When sched_ext is disabled, the
system restores the previous deadline bandwidth values and behavior.
The transition logic ensures that switching between scheduling modes is
consistent and reversible, without losing runtime configuration or
requiring manual intervention.
Signed-off-by: Andrea Righi <arighi@nvidia.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Juri Lelli <juri.lelli@redhat.com>
Link: https://patch.msgid.link/20260526164420.638711-2-arighi@nvidia.com
Writing runtime or period via the per-CPU dl_server debugfs files
(/sys/kernel/debug/sched/{fair,ext}_server/cpu*/{runtime,period}) on an
offline CPU can trigger two distinct kernel issues:
1) Divide-by-zero in dl_server_apply_params():
Oops: divide error: 0000 [#1] SMP NOPTI
RIP: 0010:dl_server_apply_params+0x239/0x3a0
Call Trace:
sched_server_write_common.isra.0+0x21a/0x3c0
full_proxy_write+0x78/0xd0
vfs_write+0xe7/0x6e0
Both __dl_sub() and __dl_add() divide by cpus internally, which can be
0 once the CPU has been removed from any active root-domain span (this
has been latent since the debugfs interface was introduced).
2) WARN_ON_ONCE in dl_server_start():
WARNING: kernel/sched/deadline.c:1805 at dl_server_start+0x232/0x270
Commit ee6e44dfe6 ("sched/deadline: Stop dl_server before CPU goes
offline") added this check to catch enqueueing the server on an
offline rq.
There's no meaningful semantics for re-configuring the per-CPU dl_server
bandwidth while the CPU is offline, so simply reject the write with
-EBUSY so userspace gets a clear error.
Closes: https://lore.kernel.org/all/20260526092228.3B6891F00A3A@smtp.kernel.org/
Fixes: d741f297bc ("sched/fair: Fair server interface")
Reported-by: Sashiko <sashiko-bot@kernel.org>
Signed-off-by: Andrea Righi <arighi@nvidia.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Juri Lelli <juri.lelli@redhat.com>
Tested-by: abaci-kreproducer <abaci@linux.alibaba.com>
Link: https://patch.msgid.link/20260526100502.575774-1-arighi@nvidia.com
Venkat Reported a boot kernel panic next-20260522. Git bisect pointed to
b5ea300a17 ("sched/cache: Make LLC id continuous")
Stacktrace points to llc_mask being null.
NIP [c000000000e58504] _find_first_bit+0x44/0x130
LR [c000000000e58500] _find_first_bit+0x40/0x130
Call Trace:
build_sched_domains+0xad8/0xe50
sched_init_smp+0xa8/0x164
kernel_init_freeable+0x250/0x370
ret_from_kernel_user_thread+0x14/0x1c
On powerpc, cpu_coregroup_mask is available only when the underlying
hardware support coregroup. In shared LPAR, QEMU guest or power9 etc
coregroup isn't supported. In such cases llc_mask was being referenced
when it was null leading to panic.
On powerpc, LLC is at SMT core level. So assumption that coregroup(MC)
domain point to LLC is wrong. Provide a way for archs to say where its
LLC is if it not at MC domain.
Fixes: b5ea300a17 ("sched/cache: Make LLC id continuous")
Closes: https://lore.kernel.org/all/51154de7-3700-4cb4-82f2-1b3a8fa427f7@linux.ibm.com/
Reported-by: Venkat Rao Bagalkote <venkat88@linux.ibm.com>
Co-developed-by: Chen, Yu C <yu.c.chen@intel.com>
Signed-off-by: Shrikanth Hegde <sshegde@linux.ibm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Chen Yu <yu.c.chen@intel.com>
Tested-by: Venkat Rao Bagalkote <venkat88@linux.ibm.com>
Tested-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Link: https://patch.msgid.link/20260529075712.1181039-1-sshegde@linux.ibm.com
Allow the same userspace thread to simultaneously collect normal coverage
in syscall context (KCOV_ENABLE) and remote coverage of asynchronous work
created by the thread (KCOV_REMOTE_ENABLE). With this, remote KCOV
coverage becomes useful for generic fuzzing and not just fuzzing of
specific data injection interfaces.
This requires that the task_struct::kcov_* fields are separated into ones
that are used by the task that generates coverage, and ones that are used
by the task that requested remote coverage. To split this up:
- Split task_struct::kcov into kcov and kcov_remote. kcov_task_exit() now
has to clean up both separately.
- Only use task_struct::kcov_mode on the task that generates coverage.
- Only reset task_struct::kcov_handle on the task that requested remote
coverage.
After this change, fields used by the task that generates coverage are:
- kcov_mode
- kcov_size
- kcov_area
- kcov
- kcov_sequence
- kcov_softirq
Fields used by the task that requested remote coverage are:
- kcov_remote
- kcov_handle
[jannh@google.com: remove unused constant KCOV_MODE_REMOTE, per Dmitry]
Link: https://lore.kernel.org/20260515-kcov-simultaneous-remote-v2-1-56fde1cfa509@google.com
[jannh@google.com: update documentation on remote coverage collection]
Link: https://lore.kernel.org/20260519-kcov-docs-v1-1-5bb22f4cb20c@google.com
[jannh@google.com: move and reword sentence on simultaneous normal/remote collection
Link: https://lore.kernel.org/20260520-kcov-docs-v2-1-819f78778763@google.com
Link: https://lore.kernel.org/20260505-kcov-simultaneous-remote-v1-1-a670ba7cefd2@google.com
Signed-off-by: Jann Horn <jannh@google.com>
Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Marco Elver <elver@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Store common handle IDs in "struct kcov_common_handle_id", which consumes
no space in non-KCOV builds.
This cleanup removes #ifdef boilerplate code from subsystems that
integrate with KCOV (in particular in usbip_common.h and skbuff.h, see the
diffstat).
This should also make it easier to add KCOV remote coverage to more
subsystems in the future.
Link: https://lore.kernel.org/20260430-kcov-refactor-common-handle-v1-1-23a0c7a0ba38@google.com
Signed-off-by: Jann Horn <jannh@google.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
Acked-by: Jakub Kicinski <kuba@kernel.org>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Eugenio Pérez <eperezma@redhat.com>
Cc: Hongren (Zenithal) Zheng <i@zenithal.me>
Cc: Jann Horn <jannh@google.com>
Cc: Jason Wang <jasowang@redhat.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Valentina Manea <valentina.manea.m@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Patch series "taskstats: fix TGID dead-thread stat retention", v3.
This series fixes a taskstats TGID aggregation bug where fields added in
the TGID query path were not preserved after thread exit, and adds a
kselftest covering the regression.
The first patch keeps the cached TGID aggregate used for dead threads in
step with the fields already accumulated for live threads, and also fixes
the final TGID exit notification emitted when group_dead is true.
The second patch adds a kselftest that verifies TGID CPU stats do not
regress after a worker thread exits and has been reaped.
This patch (of 2):
fill_stats_for_tgid() builds TGID stats from two sources: the cached
aggregate in signal->stats and a scan of the live threads in the group.
However, fill_tgid_exit() only accumulates delay accounting into
signal->stats. This means that once a thread exits, TGID queries lose the
fields that fill_stats_for_tgid() adds for live threads.
This gap was introduced incrementally by two earlier changes that extended
fill_stats_for_tgid() but did not make the corresponding update to
fill_tgid_exit():
- commit 8c733420bd ("taskstats: add e/u/stime for TGID command")
added ac_etime, ac_utime, and ac_stime to the TGID query path.
- commit b663a79c19 ("taskstats: add context-switch counters")
added nvcsw and nivcsw to the TGID query path.
As a result, those fields were accounted for live threads in TGID queries,
but were dropped from the cached TGID aggregate after thread exit. The
final TGID exit notification emitted when group_dead is true also copies
that cached aggregate, so it loses the same fields.
Factor the per-task TGID accumulation into tgid_stats_add_task() and use
it in both fill_stats_for_tgid() and fill_tgid_exit(). This keeps the
cached aggregate used for dead threads aligned with the live-thread
accumulation used by TGID queries.
Link: https://lore.kernel.org/cover.1776094300.git.cyyzero16@gmail.com
Link: https://lore.kernel.org/abd2a15d33343636ab5ba43d540bcfe508bd66c7.1776094300.git.cyyzero16@gmail.com
Fixes: 8c733420bd ("taskstats: add e/u/stime for TGID command")
Fixes: b663a79c19 ("taskstats: add context-switch counters")
Signed-off-by: Yiyang Chen <cyyzero16@gmail.com>
Acked-by: Balbir Singh <balbirs@nvidia.com>
Cc: Dr. Thomas Orgis <thomas.orgis@uni-hamburg.de>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Wang Yaxin <wang.yaxin@zte.com.cn>
Cc: Yang Yang <yang.yang29@zte.com.cn>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
HW-tag KASAN never checks kernel stacks because stack pointers carry the
match-all tag, so setting/poisoning tags is pure overhead.
- Add __GFP_SKIP_KASAN to THREADINFO_GFP so every stack allocator that
uses it skips tagging (fork path plus arch users)
- Add __GFP_SKIP_KASAN to GFP_VMAP_STACK for the fork-specific vmap
stacks.
- When reusing cached vmap stacks, skip kasan_unpoison_range() if HW tags
are enabled.
Software KASAN is unchanged; this only affects tag-based KASAN.
Link: https://lore.kernel.org/20260429102704.680174-3-dev.jain@arm.com
Signed-off-by: Muhammad Usama Anjum <usama.anjum@arm.com>
Signed-off-by: Dev Jain <dev.jain@arm.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Ben Segall <bsegall@google.com>
Cc: David Hildenbrand (Arm) <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: K Prateek Nayak <kprateek.nayak@amd.com>
Cc: Liam Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: "Uladzislau Rezki (Sony)" <urezki@gmail.com>
Cc: Valentin Schneider <vschneid@redhat.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Vlastimil Babka <vbabka@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Pages that BPF arena code maps are allocated through
bpf_map_alloc_pages(), which does not allocate folios but pages.
In the future, pages will not have a mapcount, only folios will.
Converting the code to use folios and rely on folio_mapped() sounds like
the wrong approach.
Should BPF arena code allocate folios and use folio_mapped() here? But
likely we would not want to use folios here longterm, as we don't really
need folio information.
Hard to tell. But in the meantime, we can simply use the page refcount
instead, as a heuristic whether the page might be mapped to user space and
we would want to try zapping it, so we can get rid of page_mapped().
Page allocation will give us a page with a refcount of 1. Any user space
mapping adds a page reference. While there can be references from other
subsystems (e.g., GUP), in the common case for this test here relying on
the page count is good enough.
Link: https://lore.kernel.org/20260427-page_mapped-v1-2-e89c3592c74c@kernel.org
Signed-off-by: David Hildenbrand (Arm) <david@kernel.org>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Andrii Nakryiko <andrii@kernel.org>
Cc: Eduard Zingerman <eddyz87@gmail.com>
Cc: Harry Yoo <harry@kernel.org>
Cc: Jann Horn <jannh@google.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Cc: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Martin KaFai Lau <martin.lau@linux.dev>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Rich Felker <dalias@libc.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Song Liu <song@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: Yonghong Song <yonghong.song@linux.dev>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Because there is time gap between bpf_map_new_fd() and close_fd(), a
concurrent thread is able to close the new fd and opens a new, unrelated
file with the exact same fd number. Thereafter, this close_fd() might
inadvertently close the unrelated file.
To avoid such regression, do finalize log before security_bpf_map_create().
However, in order to achieve it, move bpf_get_file_flag(),
security_bpf_map_create(), bpf_map_alloc_id(), and bpf_map_new_fd() from
__map_create() to map_create(). And, rename __map_create() to
map_create_alloc() meanwhile.
Then, in order to reuse the map and token when all checks pass in
map_create_alloc(), pass "struct bpf_map **" and "struct bpf_token **" to
map_create_alloc().
Fixes: 49f9b2b2a1 ("bpf: Add syscall common attributes support for map_create")
Signed-off-by: Leon Hwang <leon.hwang@linux.dev>
Link: https://lore.kernel.org/r/20260521142909.95818-1-leon.hwang@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
When the persistent ring buffer is validated on boot up, if a subbuffer is
deemed invalid, it resets the buffer and continues. Have the code preserve
the RB_MISSED_EVENTS flag in the commit portion of the subbuffer header
and pass that back so that the trace_pipe file can show the missed events
like the trace file does.
For example:
<...>-1242 [005] d.... 4429.120116: page_fault_user: address=0x7ffaebb6e728 ip=0x7ffaeb9d4960 error_code=0x7
<...>-1242 [005] ..... 4429.120124: mm_page_alloc: page=00000000055254f3 pfn=0x1373bd order=0 migratetype=1 gfp_flags=GFP_HIGHUSER_MOVABLE|__GFP_COMP
<...>-1242 [005] d..2. 4429.120132: tlb_flush: pages:1 reason:local MM shootdown (3)
CPU:5 [LOST EVENTS]
<...>-1242 [005] d.... 4429.120661: page_fault_user: address=0x55ba7c2d0944 ip=0x55ba7c20cd02 error_code=0x7
<...>-1242 [005] ..... 4429.120669: mm_page_alloc: page=0000000005a02500 pfn=0x12b6e4 order=0 migratetype=1 gfp_flags=GFP_HIGHUSER_MOVABLE|__GFP_COMP
<...>-1242 [005] d..2. 4429.120680: tlb_flush: pages:1 reason:local MM shootdown (3)
Link: https://patch.msgid.link/20260522171052.156419479@kernel.org
Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
When the persistent ring buffer is validated on boot up, if a subbuffer is
deemed invalid, it resets the buffer and continues. Currently, these lost
events are not shown in the trace file output.
Have the trace iterator look for subbuffers that have the RB_MISSED_EVENTS
set and set the iter->missed_events flag when it is detected. This will
then have the trace file shows "LOST EVENTS" when it reads across a
subbuffer that was corrupted and invalidated.
For example:
<...>-1016 [005] ...1. 6230.660403: preempt_disable: caller=__mod_memcg_state+0x1c8/0x200 parent=__mod_memcg_state+0x1c8/0x200
CPU:5 [LOST EVENTS]
<...>-1016 [005] ..... 6230.660673: kmem_cache_alloc: call_site=__anon_vma_prepare+0x1ad/0x1e0 ptr=000000006e40294c name=anon_vma bytes_req=200 bytes_alloc=208 gfp_flags=GFP_KERNEL node=-1 accounted=true
Link: https://patch.msgid.link/20260522171052.006276604@kernel.org
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
When the persistent ring buffer detects a corrupted subbuffer, it will
zero its size and report dropped pages in the dmesg, then it continues
normally.
But if a reboot happens without clearing or restarting tracing on the
persistent ring buffer, the next boot will show no pages are dropped.
If the persistent ring buffer is still the same, then it should still
report dropped pages so the user knows that the buffer has missing events.
Add the RB_MISSED_EVENTS flag to the commit value of the subbuffer so that
the next boot will still show that pages were dropped.
Link: https://patch.msgid.link/20260522171051.860780286@kernel.org
Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Code cleanup related to buffer_data_page for readability,
which includes:
- Introduce rb_data_page_commit() and rb_data_page_size()
- Use 'dpage' for buffer_data_page, instead of 'bpage' because
'bpage' is used for buffer_page.
Link: https://patch.msgid.link/20260522171051.722645963@kernel.org
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Cleanup rb_meta_validate_events() function to make it easier to read.
This includes the following cleanups:
- Introduce rb_validatation_state to hold working variables in
validation.
- Move repleated validation state updates into rb_validate_buffer().
- Move reader_page injection code outside of rb_meta_validate_events().
Link: https://patch.msgid.link/20260522171051.577231395@kernel.org
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
In addition to the index number, show the commit numbers of
each data page in the per_cpu buffer_meta file.
This is useful for understanding the current status of the
persistent ring buffer. (Note that this file is shown
only for persistent ring buffer and its backup instance)
Link: https://patch.msgid.link/20260522171051.424411323@kernel.org
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Add a self-corrupting test for the persistent ring buffer.
This will inject an erroneous value to some sub-buffer pages (where
the index is even or multiples of 5) in the persistent ring buffer
when the kernel panics, and checks whether the number of detected
invalid pages and the total entry_bytes are the same as the recorded
values after reboot.
This ensures that the kernel can correctly recover a partially
corrupted persistent ring buffer after a reboot or panic.
The test only runs on the persistent ring buffer whose name is
"ptracingtest". The user has to fill it with events before a
kernel panic.
To run the test, enable CONFIG_RING_BUFFER_PERSISTENT_INJECT
and add the following kernel cmdline:
reserve_mem=20M:2M:trace trace_instance=ptracingtest^traceoff@trace
panic=1
Run the following commands after the 1st boot:
cd /sys/kernel/tracing/instances/ptracingtest
echo 1 > tracing_on
echo 1 > events/enable
sleep 3
echo c > /proc/sysrq-trigger
After panic message, the kernel will reboot and run the verification
on the persistent ring buffer, e.g.
Ring buffer meta [2] invalid buffer page detected
Ring buffer meta [2] is from previous boot! (318 pages discarded)
Ring buffer testing [2] invalid pages: PASSED (318/318)
Ring buffer testing [2] entry_bytes: PASSED (1300476/1300476)
Link: https://patch.msgid.link/20260522171051.260140328@kernel.org
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Skip invalid sub-buffers when rewinding the persistent ring buffer
instead of stopping the rewinding the ring buffer. The skipped
buffers are cleared.
To ensure the rewinding stops at the unused page, this also clears
buffer_data_page::time_stamp when tracing resets the buffer. This
allows us to identify unused pages and empty pages.
Link: https://patch.msgid.link/20260522171051.091265852@kernel.org
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
[ SDR: Have reader_page still get evaluated if header_page fails ]
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Skip invalid sub-buffers when validating the persistent ring buffer
instead of discarding the entire ring buffer. Only skipped buffers
are invalidated (cleared).
If the cache data in memory fails to be synchronized during a reboot,
the persistent ring buffer may become partially corrupted, but other
sub-buffers may still contain readable event data. Only discard the
subbuffers that are found to be corrupted.
Link: https://lore.kernel.org/all/20260520185018.051228084@kernel.org/
Link: https://patch.msgid.link/20260522171050.914418536@kernel.org
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
[SDR: Fixed max_loops in rb_iter_peek() as well ]
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Stack traces often contain adjacent IPs from the same VMA or from
different VMAs backed by the same ELF file. Cache the last successfully
parsed build id together with the resolved VMA range and backing file
so the sleepable build id path can avoid repeated VMA locking and file
parsing in common cases.
Suggested-by: Mykyta Yatsenko <yatsenko@meta.com>
Signed-off-by: Ihor Solodrai <ihor.solodrai@linux.dev>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Mykyta Yatsenko <yatsenko@meta.com>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20260525223948.1920986-4-ihor.solodrai@linux.dev
Commit 8312cab5ff ("timers/migration: Rename 'online' bit to
'available'") renamed the 'online' field of struct tmigr_cpu to
'available'. The kernel doc comment above the struct still describes the
old field name.
Update it to reflect the actual field name and use the 'available' wording
in the description.
Fixes: 8312cab5ff ("timers/migration: Rename 'online' bit to 'available'")
Signed-off-by: Zhan Xusheng <zhanxusheng@xiaomi.com>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Link: https://patch.msgid.link/20260526022106.1302279-1-zhanxusheng@xiaomi.com
cgroup.max.descendants and cgroup.max.depth are shown through seq_file.
Their show callbacks read cgrp->max_descendants and cgrp->max_depth with
READ_ONCE(), respectively.
The corresponding write callbacks update the same scalar fields while
holding the cgroup lock, but the seq_file show path does not serialize
against those stores. This leaves the lockless show-side loads annotated
with READ_ONCE(), while the corresponding stores remain plain stores.
Use WRITE_ONCE() for the updates so the intended lockless access is marked
consistently on both sides. This does not change locking, ordering, or
user-visible semantics.
Assisted-by: OpenAI-Codex:gpt-5.5
Signed-off-by: Ren Tamura <ren.tamura.oss@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Currently, there are 2 kernel cmdline ways to setup numa cma area:
"cma_pernuma=" and "numa_cma=", and there are 2 cma arrays as well,
while they have no difference technically. Robin suggested to cleanup
the code and only use one array [1], as "the apparent intent that
users only want one _or_ the other".
Simplify the code by only using one array to save the numa cma area.
And in rare case that a user really setup the 2 cmdline parameters
at the same time, let the per-node specific size setting 'numa_cma='
take priority over the global numa cma setting.
Link[1]: https://lore.kernel.org/lkml/43c5301c-fe6a-41e4-9482-ccfc7b62f2a7@arm.com/
Suggested-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Feng Tang <feng.tang@linux.alibaba.com>
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Link: https://lore.kernel.org/r/20260525015111.6267-1-feng.tang@linux.alibaba.com
A deadlock occurs in the audit subsystem when duplicating
executable-related rules.
When a file is moved (e.g., via do_renameat2()), the VFS layer locks
the parent directory (I_MUTEX_PARENT), which synchronously triggers an
fsnotify_move event. If an existing executable audit rule matches the
file being moved, the audit subsystem catches this event and calls
audit_dupe_exe() to duplicate the watch and update the rule. Then,
audit_alloc_mark() would call kern_path_parent() to resolve the path,
leading to a blind attempt to acquire the exact same I_MUTEX_PARENT lock
already held by the task, resulting in the following recursive locking
deadlock:
============================================
WARNING: possible recursive locking detected
6.12.0-55.27.1.el10_0.x86_64+debug #1 Not tainted
--------------------------------------------
mv/5099 is trying to acquire lock:
ffff888132845358 (&inode->i_sb->s_type->i_mutex_dir_key/1){+.+.}-{3:3},
at: __kern_path_locked+0x10a/0x2f0
but task is already holding lock:
ffff888132846b58 (&inode->i_sb->s_type->i_mutex_dir_key/1){+.+.}-{3:3},
at: lock_two_directories+0x13f/0x2b0
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0
----
lock(&inode->i_sb->s_type->i_mutex_dir_key/1);
lock(&inode->i_sb->s_type->i_mutex_dir_key/1);
*** DEADLOCK ***
May be due to missing lock nesting notation
6 locks held by mv/5099:
#0: ffff888112a9c440 (sb_writers#13)
at: do_renameat2+0x34c/0xbc0
#1: ffff888112a9c790 (&type->s_vfs_rename_key#3)
at: do_renameat2+0x415/0xbc0
#2: ffff888132846b58 (&inode->i_sb->s_type->i_mutex_dir_key/1)
at: lock_two_directories+0x13f/0x2b0
#3: ffff888132845358 (&inode->i_sb->s_type->i_mutex_dir_key/5)
at: lock_two_directories+0x175/0x2b0
#4: ffffffffb3a1fb10 (&fsnotify_mark_srcu)
at: fsnotify+0x454/0x28a0
#5: ffffffffaf886230 (audit_filter_mutex)
at: audit_update_watch+0x36/0x11e0
stack backtrace:
Call Trace:
<TASK>
dump_stack_lvl+0x6f/0xb0
print_deadlock_bug.cold+0xbd/0xca
validate_chain+0x83a/0xf00
__lock_acquire+0xcac/0x1d20
lock_acquire.part.0+0x11b/0x360
down_write_nested+0x9f/0x230
__kern_path_locked+0x10a/0x2f0
kern_path_locked+0x26/0x40
audit_alloc_mark+0xfb/0x4f0
audit_dupe_exe+0x6c/0xe0
audit_dupe_rule+0x6c2/0xc00
audit_update_watch+0x4cc/0x11e0
audit_watch_handle_event+0x12c/0x1b0
send_to_group+0x5d0/0x8b0
fsnotify+0x615/0x28a0
fsnotify_move+0x1d8/0x630
vfs_rename+0xdcd/0x1df0
do_renameat2+0x9d4/0xbc0
__x64_sys_renameat+0x192/0x260
do_syscall_64+0x92/0x180
entry_SYSCALL_64_after_hwframe+0x76/0x7e
RIP: 0033:0x7f0491fe8c4e
Code: 0f 1f 40 00 48 8b 15 c1 e1 16 00 f7 d8 64 89 02 b8 ff ff ff ff
c3 66 0f 1f 44 00 00 f3 0f 1e fa 49 89 ca b8 08 01 00 00 0f 05 <48>
3d 00 f0 ff ff 77 0a c3 66 0f 1f 84 00 00 00 00 00 48 8b 15 89
RSP: 002b:00007ffc7210bf38 EFLAGS: 00000246 ORIG_RAX: 0000000000000108
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f0491fe8c4e
RDX: 0000000000000003 RSI: 00007ffc7210e6c8 RDI: 00000000ffffff9c
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000001
R10: 00005575eb2dae2a R11: 0000000000000246 R12: 00005575eb2dae2a
R13: 00007ffc7210e6c8 R14: 0000000000000003 R15: 00000000ffffff9c
</TASK>
The aforementioned deadlock can be consistently reproduced by running
the script below:
audit-dupe-exe-deadlock.sh
--------------------------
#!/bin/bash
auditctl -D
mkdir -p /tmp/foo
touch /tmp/file
auditctl -a always,exit -F exe=/tmp/file -F path=/tmp/file -S all -k dr
mv /tmp/file /tmp/foo/file
rm -Rf /tmp/foo
This patch fixes the issue by introducing struct audit_watch_ctx to pass
the fsnotify event context down to audit_alloc_mark(). By utilizing the
already-resolved directory inode provided by the event, we bypass the
kern_path_parent() path resolution entirely, safely avoiding the
recursive lock. Furthermore, it explicitly allows duplicate fsnotify
marks (allow_dups = 1) during the rename update, allowing the new rule's
mark to safely coexist with the old rule's mark until the old rule is
freed.
P.S.: This issue was identified and reproduced during a comprehensive
code coverage analysis of the audit subsystem. The full report is
available at the link below:
https://people.redhat.com/rrobaina/audit-code-coverage-analysis.pdf
P.P.S: With the permission of both Ricardo and Nathan, I've squashed a
fixup patch from Nathan that addresses a compile time error when
CONFIG_AUDITSYSCALL=n.
Cc: stable@kernel.org
Fixes: 34d99af52a ("audit: implement audit by executable")
Acked-by: Waiman Long <longman@redhat.com>
Acked-by: Richard Guy Briggs <rgb@redhat.com>
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Ricardo Robaina <rrobaina@redhat.com>
[PM: move link metadata into the msg, apply fix from NC]
Signed-off-by: Paul Moore <paul@paul-moore.com>
On configs with CONFIG_BPF=y but CONFIG_BPF_SYSCALL=n (e.g. arm
multi_v7_defconfig), kernel/bpf/core.c defines a __weak
bpf_arena_handle_page_fault() while bpf_defs.h already supplies a static
inline stub for it, causing a redefinition error. Build the __weak
definition only under CONFIG_BPF_SYSCALL, matching the bpf_defs.h
declaration and the CONFIG_BPF_SYSCALL-gated strong definition in arena.c.
Fixes: dc11a4dba2 ("bpf: Recover arena kernel faults with scratch page")
Reported-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Song Liu <song@kernel.org>
Link: https://lore.kernel.org/r/20260527192632.2109419-1-tj@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
When sibling CPU exclusion occurs, a partition's user_xcpus may contain
CPUs that were never actually granted to it. These CPUs are present in
user_xcpus(cs) but not in cs->effective_xcpus.
The partcmd_update path in update_parent_effective_cpumask() uses
user_xcpus(cs) (via the local variable xcpus) to compute the addmask
(CPUs to return to parent) and delmask (CPUs to request from parent).
This is incorrect:
1) When newmask removes a CPU that was previously excluded by a
sibling, addmask incorrectly includes that CPU and tries to return
it to the parent even though the partition never actually owned it,
causing CPU overlap with sibling partitions and triggering warnings
in generate_sched_domains().
2) When newmask adds a previously excluded CPU that is now available,
delmask fails to request it from the parent because user_xcpus(cs)
already includes it.
Fix this by using cs->effective_xcpus instead of user_xcpus(cs) in all
partcmd_update paths that calculate addmask or delmask, including the
PERR_NOCPUS error handling paths.
Reproducers:
Example 1 - Removing a sibling-excluded CPU incorrectly returns it:
# cd /sys/fs/cgroup
# echo "0-1" > a1/cpuset.cpus
# echo "root" > a1/cpuset.cpus.partition
# echo "0-2" > b1/cpuset.cpus
# echo "root" > b1/cpuset.cpus.partition
# echo "2" > b1/cpuset.cpus
# cat cpuset.cpus.effective
# Actual: 0-1,3 Expected: 3
Example 2 - Expanding to a previously excluded CPU fails to request it:
# cd /sys/fs/cgroup
# echo "0-1" > a1/cpuset.cpus
# echo "root" > a1/cpuset.cpus.partition
# echo "0-2" > b1/cpuset.cpus
# echo "root" > b1/cpuset.cpus.partition
# echo "member" > a1/cpuset.cpus.partition
# echo "1-2" > b1/cpuset.cpus
# cat cpuset.cpus.effective
# Actual: 0-1,3 Expected: 0,3
Fixes: 2a3602030d ("cgroup/cpuset: Don't invalidate sibling partitions on cpuset.cpus conflict")
Cc: stable@vger.kernel.org # v7.0+
Suggested-by: Zhang Guopeng <zhangguopeng@kylinos.cn>
Signed-off-by: Sun Shaojie <sunshaojie@kylinos.cn>
Reviewed-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
print_worker_info() declares its local 'fn' as work_func_t * but
worker->current_func has type work_func_t (a function pointer). The
extra level of indirection is wrong and only happens to be harmless
today because every supported Linux architecture has
sizeof(work_func_t) == sizeof(work_func_t *):
copy_from_kernel_nofault() reads the correct number of bytes by
accident, and %ps still resolves the printed address because the
stored value is the function address regardless of declared type.
On any future ABI where sizeof(void (*)()) differs from
sizeof(void *), the nofault copy would transfer the wrong number of
bytes and the subsequent %ps would print an incorrect address.
Match the field type so the intent is explicit and the code does not
silently rely on equal pointer sizes.
Fixes: 3d1cb2059d ("workqueue: include workqueue info when printing debug dump of a worker task")
Signed-off-by: Breno Leitao <leitao@debian.org>
Signed-off-by: Tejun Heo <tj@kernel.org>
|| is a boolean operator, any nonzero (error) return short-circuits
to 1 rather than the actual errno. The caller in scx_init() logs and
propagates this value, so the wrong code reaches upper layers.
Signed-off-by: Cheng-Yang Chou <yphbchou0911@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
When an audited executable is deleted from the disk, its dentry
becomes negative. Any later attempt to delete the associated audit
rule will lead to audit_alloc_mark() encountering this negative
dentry and immediately aborting, returning -ENOENT.
This early abort prevents the subsystem from allocating the temporary
fsnotify mark needed to construct the search key, meaning the kernel
cannot find the existing rule in its own lists to delete it. This
leaves a dangling rule in memory, resulting in the following error
while attempting to delete the rule:
# ./audit-dupe-exe-deadlock.sh
No rules
Error deleting rule (No such file or directory)
There was an error while processing parameters
# auditctl -l
-a always,exit -S all -F exe=/tmp/file -F path=/tmp/file -F key=dr
# auditctl -D
Error deleting rule (No such file or directory)
There was an error while processing parameters
This patch fixes this issue by removing the d_really_is_negative()
check. By doing so, a dummy mark can be successfully generated for
the deleted path, which allows the audit subsystem to properly match
and flush the dangling rule.
Cc: stable@kernel.org
Fixes: 76a53de6f7 ("VFS/audit: introduce kern_path_parent() for audit")
Acked-by: Waiman Long <longman@redhat.com>
Acked-by: Richard Guy Briggs <rgb@redhat.com>
Signed-off-by: Ricardo Robaina <rrobaina@redhat.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
Address checkpatch.pl warning below, across the audit subsystem:
WARNING: Prefer 'unsigned int' to bare use of 'unsigned'
Minor cleanup, no functional changes.
Signed-off-by: Ricardo Robaina <rrobaina@redhat.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
post-7.1 issues or aren't considered suitable for backporting.
All patches are singletons - please see the individual changelogs for
details.
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Merge tag 'mm-hotfixes-stable-2026-05-25-16-22' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Pull misc fixes from Andrew Morton:
"13 hotfixes. 9 are for MM. 9 are cc:stable and the remaining 4 address
post-7.1 issues or aren't considered suitable for backporting.
All patches are singletons - please see the individual changelogs for
details"
* tag 'mm-hotfixes-stable-2026-05-25-16-22' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm:
Revert "mm: introduce a new page type for page pool in page type"
mm/vmalloc: do not trigger BUG() on BH disabled context
MAINTAINERS, mailmap: change email for Eugen Hristev
mm/migrate_device: fix pgtable leak in migrate_vma_insert_huge_pmd_page
kernel/fork: validate exit_signal in kernel_clone()
mm: memcontrol: propagate NMI slab stats to memcg vmstats
mm/damon/sysfs-schemes: delete tried region in regions_rmdirs()
mm/rmap: initialize nr_pages to 1 at loop start in try_to_unmap_one
zram: fix use-after-free in zram_writeback_endio
memfd: deny writeable mappings when implying SEAL_WRITE
ipc: limit next_id allocation to the valid ID range
Revert "mm/hugetlbfs: update hugetlbfs to use mmap_prepare"
MAINTAINERS: .mailmap: update after GEHC spin-off
Reading /proc/interrupts iterates over the interrupt number space one by
one and looks up the descriptors one by one. That's just a waste of time.
When CONFIG_GENERIC_IRQ_SHOW is enabled this can utilize the maple tree and
cache the descriptor pointer efficiently for the sequence file operations.
Implement a CONFIG_GENERIC_IRQ_SHOW specific version in the core code and
leave the fs/proc/ variant for the legacy architectures which ignore generic
code.
This reduces the time wasted for looking up the next record significantly.
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Tested-by: Michael Kelley <mhklinux@outlook.com>
Reviewed-by: Dmitry Ilvokhin <d@ilvokhin.com>
Link: https://patch.msgid.link/20260517194932.165280601@kernel.org
The chip name column in the /proc/interrupt output is 8 characters and
right aligned, which causes visual clutter due to the fixed length and the
alignment. Many interrupt chips, e.g. PCI/MSI[X] have way longer names.
Update the length when a chip is assigned to an interrupt and utilize this
information for the output. Align it left so all chip names start at the
begin of the column.
Update the GDB script as well and disentangle the header maze so it
actually works with all .config combinations.
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Tested-by: Michael Kelley <mhklinux@outlook.com>
Reviewed-by: Dmitry Ilvokhin <d@ilvokhin.com>
Link: https://patch.msgid.link/20260517194932.085786035@kernel.org
... in preparation for a smarter iterator for /proc/interrupts.
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Tested-by: Michael Kelley <mhklinux@outlook.com>
Reviewed-by: Dmitry Ilvokhin <d@ilvokhin.com>
Link: https://patch.msgid.link/20260517194932.005787611@kernel.org
Prepare for a smarter iterator for /proc/interrupts so that the next
interrupt descriptor can be cached after lookup.
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Tested-by: Michael Kelley <mhklinux@outlook.com>
Reviewed-by: Dmitry Ilvokhin <d@ilvokhin.com>
Link: https://patch.msgid.link/20260517194931.917415190@kernel.org
Quite some architectures have four character wide acronyms for architecture
specific interrupts like IPI, NMI, etc.
The default precision of printing the Linux device interrupt numbers is
three, which causes quite some code to play games with adding or omitting
space after the acronym and the colon in order to keep the per CPU numbers
properly aligned.
Increase the default number precision to four in the core code and get rid
of the space games all over the place. At the same time align all
architecture specific descriptor texts left so that they show up in the
same column as the interrupt chip names, which makes the output more
uniform accross architectures. Fix up the GDB script to this new scheme as
well.
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Link: https://patch.msgid.link/20260517194931.839482411@kernel.org
Calculating the precision of the interrupt number column on every initial
show_interrupt() invocation is a pointless exercise as the underlying
maximum number of interrupts rarely changes.
Calculate it only when that number is modified and let show_interrupts()
use the cached value.
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Tested-by: Michael Kelley <mhklinux@outlook.com>
Reviewed-by: Dmitry Ilvokhin <d@ilvokhin.com>
Reviewed-by: Radu Rendec <radu@rendec.net>
Link: https://patch.msgid.link/20260517194931.760664517@kernel.org
show_interrupts() evaluates a boatload of conditions to establish whether
it should expose an interrupt in /proc/interrupts or not.
That can be simplified by caching the condition in an internal status flag,
which is updated when one of the relevant inputs changes.
The irq_desc::kstat_irq check is dropped because visible interrupt
descriptors always have a valid pointer.
As a result the number of instructions and branches for reading
/proc/interrupts is reduced significantly.
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Tested-by: Michael Kelley <mhklinux@outlook.com>
Reviewed-by: Dmitry Ilvokhin <d@ilvokhin.com>
Reviewed-by: Radu Rendec <radu@rendec.net>
Link: https://patch.msgid.link/20260517194931.680943749@kernel.org
Eventually blocking functions cannot be invoked with interrupts disabled
and a raw spin lock held. Restructure the code so this happens outside of
the descriptor lock held region.
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Tested-by: Michael Kelley <mhklinux@outlook.com>
Link: https://patch.msgid.link/20260517194931.601972758@kernel.org
... to avoid function calls in the core code to retrieve the maximum number
of interrupts.
Rename it to 'total_nr_irqs' as 'nr_irqs' is too generic and fix up the
'nr_irqs' reference in the related GDB script as well.
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Tested-by: Michael Kelley <mhklinux@outlook.com>
Reviewed-by: Dmitry Ilvokhin <d@ilvokhin.com>
Reviewed-by: Radu Rendec <radu@rendec.net>
Reviewed-by: Shrikanth Hegde <sshegde@linux.ibm.com>
Link: https://patch.msgid.link/20260517194931.522168332@kernel.org
Interrupts which are not marked per CPU increment not only the per CPU
statistics, but also the accumulation counter irq_desc::tot_count.
Change the counter to type unsigned long so it does not produce sporadic
zeros due to wrap arounds on 64-bit machines and do a quick check for non
per CPU interrupts. If the counter is zero, then simply emit a full set of
zero strings. That spares the evaluation of the per CPU counters completely
for interrupts with zero events.
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Tested-by: Michael Kelley <mhklinux@outlook.com>
Reviewed-by: Dmitry Ilvokhin <d@ilvokhin.com>
Reviewed-by: Radu Rendec <radu@rendec.net>
Link: https://patch.msgid.link/20260517194931.115522199@kernel.org
A large portion of interrupt count entries are zero. There is no point in
formatting the zero value as it is way cheeper to just emit a constant
string.
Collect the number of consecutive zero counts and emit them in one go
before a non-zero count and at the end of the line.
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Tested-by: Michael Kelley <mhklinux@outlook.com>
Reviewed-by: Dmitry Ilvokhin <d@ilvokhin.com>
Reviewed-by: Radu Rendec <radu@rendec.net>
Reviewed-by: Shrikanth Hegde <sshegde@linux.ibm.com>
Link: https://patch.msgid.link/20260517194931.034728540@kernel.org
The CRC uncompressed buffer pointer array has the same lifetime as
struct crc_data, but it is currently allocated separately. That adds
another allocation failure path and a matching cleanup branch without
providing any extra flexibility.
Store the pointer array as a flexible array member and allocate it
together with the crc_data using kzalloc_flex(). The array remains
zero-initialized, while the allocation and error handling become
simpler.
Assisted-by: Codex:GPT-5.5
Signed-off-by: Rosen Penev <rosenp@gmail.com>
Link: https://patch.msgid.link/20260510213948.41750-1-rosenp@gmail.com
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
The reason for pick_next_task_fair() is the put/set optimization that
avoids touching the common ancestors. However, it is possible to
implement this in the put_prev_task() and set_next_task() calls as
used in put_prev_set_next_task().
Notably, put_prev_set_next_task() is the only site that:
- calls put_prev_task() with a .next argument;
- calls set_next_task() with .first = true.
This means that put_prev_task() can determine the common hierarchy and
stop there, and then set_next_task() can terminate where put_prev_task
stopped.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://patch.msgid.link/20260511120628.057634261@infradead.org
With commit 50653216e4 ("sched: Add support to pick functions to
take rf") removing the balance callback, the pick_task() callback is
in charge of newidle balancing.
This means pick_task_fair() should do so too. This hasn't been a
problem in practise because pick_next_task_fair() is used. However,
since we'll be removing that one shortly, make sure pick_next_task()
is up to scratch.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://patch.msgid.link/20260511120627.944705718@infradead.org
Robots figured out you can read and write this concurrently and got
'upset'. Gemini even noted sched_dynamic_show() can generate
'confusing' output if it observed different values during the
printing.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260511120627.176946327@infradead.org
Commit c9d93a73ce ("sched/fair: Drop redundant RCU read lock in NOHZ
kick path") removed the rcu_read_lock()/unlock() pair from
set_cpu_sd_state_busy() and set_cpu_sd_state_idle() on the assumption
that all callers run in a safe context for rcu_dereference_all(): IRQs
disabled or cpus_write_lock() held.
That assumption is wrong for the CPU hotplug teardown path. When CPUs
are taken offline, set_cpu_sd_state_busy() is invoked via:
cpuhp/N kthread
cpuhp_thread_fun()
cpuhp_invoke_callback()
sched_cpu_deactivate()
nohz_balance_exit_idle()
set_cpu_sd_state_busy()
rcu_dereference_all(per_cpu(sd_llc, cpu))
The cpuhp kthread holds cpu_hotplug_lock (percpu-rwsem) but runs with
preemption and IRQs enabled. As a result, lockdep correctly reports a
suspicious RCU usage on CPU offline, e.g.:
# echo 0 > /sys/devices/system/cpu/cpu1/online
=============================
WARNING: suspicious RCU usage
-----------------------------
kernel/sched/fair.c:12793 suspicious rcu_dereference_check() usage!
...
2 locks held by cpuhp/1/20:
#0: (cpu_hotplug_lock){++++}-{0:0}, at: cpuhp_thread_fun+0x42/0x1ae
#1: (cpuhp_state-down){+.+.}-{0:0}, at: cpuhp_thread_fun+0x72/0x1ae
Call Trace:
lockdep_rcu_suspicious
nohz_balance_exit_idle
sched_cpu_deactivate
cpuhp_invoke_callback
cpuhp_thread_fun
smpboot_thread_fn
Fix this by adding RCU read lock coverage to the one caller that lacks
it: nohz_balance_exit_idle() in the CPU hotplug teardown.
The other callers (nohz_balancer_kick() and nohz_balance_enter_idle())
genuinely run with IRQs disabled, so they remain unchanged.
Fixes: c9d93a73ce ("sched/fair: Drop redundant RCU read lock in NOHZ kick path")
Closes: https://lore.kernel.org/all/38fe0a1d-1a48-435a-910a-c278024d9ac9@samsung.com/
Reported-by: Marek Szyprowski <m.szyprowski@samsung.com>
Suggested-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Andrea Righi <arighi@nvidia.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260522092523.2046095-1-arighi@nvidia.com
Without this, CRYPTO_LZ4 had to be manually enabled in the config
to use LZ4 for hibernation compression. Add the select so it gets
pulled in automatically when hibernation is enabled, just like
CRYPTO_LZO already does.
Tested-by: l1rox3 <l1rox3.developer@gmail.com>
Signed-off-by: l1rox3 <l1rox3.developer@gmail.com>
Link: https://patch.msgid.link/20260520081254.13493-1-l1rox3.developer@gmail.com
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
The dumpable flag captured at execve() is consulted by
__ptrace_may_access() and several /proc owner / visibility checks.
It lives on mm_struct today, which exit_mm() clears from the task
long before the task itself is reaped.
exec_state is anchored to the execve() that established the current
privilege domain. CLONE_VM siblings refcount-share the parent's
exec_state via copy_exec_state(); non-CLONE_VM clones allocate a
fresh exec_state inheriting the parent's dumpable mode and user_ns
reference via task_exec_state_copy(). execve() allocates a fresh
instance (via alloc_task_exec_state() in begin_new_exec()) and
installs it under task_lock + exec_update_lock with
task_exec_state_replace(). init_task uses a static instance.
The dumpable mode now lives on task->exec_state->dumpable.
task->mm->flags no longer carries dumpability; MMF_DUMPABLE_MASK is
removed, but MMF_DUMPABLE_BITS is reserved so MMF_DUMP_FILTER_* bit
positions remain stable for the /proc/<pid>/coredump_filter ABI. The
task->user_dumpable cache bit and its assignment in exit_mm() are
removed; readers go through get_dumpable(task) directly.
coredump_params gains a snapshot field cprm.dumpable, populated from
get_dumpable(current) at vfs_coredump() entry, replacing the previous
__get_dumpable(cprm->mm_flags) consumers in fs/coredump.c and
fs/pidfs.c.
The user namespace recorded at execve() is consulted by
__ptrace_may_access() and by /proc/PID/* owner derivation. Move the
captured user_ns onto task_exec_state, which stays attached to the task
past exit_mm() and across exit_files().
bprm grows a user_ns field staged in bprm_mm_init() with the caller's
user_ns, narrowed by would_dump() to the closest privileged ancestor,
and consumed by exec_mmap() via alloc_task_exec_state(bprm->user_ns).
free_bprm() releases the staging reference.
mm_struct loses ->user_ns entirely. Initializers in init-mm, efi_mm,
and the implicit one in mm_init()/dup_mm()/mm_alloc() are removed;
__mmdrop() drops the matching put_user_ns(). The kthread_use_mm()
WARN_ON_ONCE(!mm->user_ns) is no longer meaningful and goes too.
Reviewed-by: Jann Horn <jannh@google.com>
Link: https://patch.msgid.link/20260520-work-task_exec_state-v3-4-69f895bc1385@kernel.org
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
Add a helper that encapsulates all of the logic for checking ptrace
access and remove open-coded versions in follow-up patches.
Reviewed-by: Jann Horn <jannh@google.com>
Reviewed-by: David Hildenbrand (arm) <david@kernel.org>
Link: https://patch.msgid.link/20260520-work-task_exec_state-v3-3-69f895bc1385@kernel.org
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
Introduce struct task_exec_state, a per-task RCU-protected structure
that holds the dumpable mode and the user namespace and stays attached
to the task for its full lifetime.
task_exec_state_rcu() is the canonical reader: asserts RCU or
task_lock is held, WARNs on a NULL state, returns the
rcu_dereference()'d pointer.
Reviewed-by: Jann Horn <jannh@google.com>
Link: https://patch.msgid.link/20260520-work-task_exec_state-v3-2-69f895bc1385@kernel.org
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
Replace the SUID_DUMP_DISABLE/USER/ROOT preprocessor constants with
enum task_dumpable. Numeric values are preserved (kernel.suid_dumpable
sysctl and prctl(PR_SET_DUMPABLE) ABI), so this is a pure rename with
no behavioral change.
Subsequent commits relocate dumpability onto a per-task structure
where the enum type will allow stronger type-checking on the new API.
Reviewed-by: Jann Horn <jannh@google.com>
Reviewed-by: David Hildenbrand (arm) <david@kernel.org>
Link: https://patch.msgid.link/20260520-work-task_exec_state-v3-1-69f895bc1385@kernel.org
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
Commit 91e74fa8b1 ("kho: make sure preservations do not span multiple
NUMA nodes") made sure preservations from kho_preserve_pages() do not
span multiple NUMA nodes. If they do, the order is reduced and tried
again.
The same logic was not implemented for kho_unpreserve_pages(). This can
result in unpreserve calculating a different order than preserve, and
thus not actually unpreserving the pages.
Fix this by moving the order calculation logic to
__kho_preserve_pages_order() and use it from both preserve and
unpreserve paths.
Move __kho_unpreserve() down to avoid having a forward declaration. Its
users are further down in the file anyway. Also, it results in grouping
for all the page-level preservation and unpreservation functions. This
unfortunately makes the diff hard to read, but the main change in
__kho_unpreserve() is to call __kho_preserve_pages_order() instead of
open-coding the order calculation.
Fixes: 91e74fa8b1 ("kho: make sure preservations do not span multiple NUMA nodes")
Cc: stable@vger.kernel.org
Signed-off-by: Pratyush Yadav (Google) <pratyush@kernel.org>
Reviewed-by: Samiullah Khawaja <skhawaja@google.com>
Reviewed-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Link: https://patch.msgid.link/20260519133332.2498092-1-pratyush@kernel.org
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
ops_cid.set_cmask() expects a cmask. The kernel couldn't write into the
arena, so it translated cpumask -> cmask in kernel memory and passed the
result as a trusted pointer. The BPF cmask helpers all operate on arena
cmasks though, so the BPF side had to word-by-word probe-read the kernel
cmask into an arena cmask via cmask_copy_from_kernel() before any helper
could touch it. It works, but is clumsy.
With direct kernel-side arena access now in place, build the cmask in the
arena. The kernel writes to it through the kern_va side of the dual mapping.
BPF directly dereferences it via an __arena pointer like any other arena
struct.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Emil Tsalapatis <emil@etsalapatis.com>
Build a per-scheduler sub-allocator on top of pages claimed from the BPF
arena registered in the previous patch. Subsequent kernel-managed
arena-resident structures (e.g. per-CPU set_cmask cmask) carve their storage
from this pool.
scx_arena_pool_init() creates a gen_pool. scx_arena_alloc() returns the
kernel VA. On exhaustion, the pool grows by claiming more pages via
bpf_arena_alloc_pages_sleepable(). Chunks are added at the kernel-side
mapping address. Callers translate to the BPF-arena form themselves if
needed.
Allocations sleep (GFP_KERNEL) - they may grow the pool through vzalloc and
arena page allocation. All current consumers run from the enable path (after
ops.init() and the kernel-side arena auto-discovery, before validate_ops()),
where sleeping is fine.
scx_arena_pool_destroy() walks each chunk, returns outstanding ranges to the
gen_pool with gen_pool_free() and then calls gen_pool_destroy(). The
underlying arena pages are released when the arena map itself is torn down,
so the pool destroy doesn't free them explicitly.
v2: Switch scx_arena_alloc() to a loop. (Andrea)
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Andrea Righi <arighi@nvidia.com>
Upcoming patches will let the kernel place arena-resident scratch shared
with the BPF program (e.g. per-CPU set_cmask cmask) so the BPF side can
dereference it directly via __arena pointers, replacing the current
cmask_copy_from_kernel() probe-read loop. That requires each cid-form
scheduler to expose its arena to the kernel. Kernel- side accesses are
recovered by the per-arena scratch-page mechanism.
bpf_scx_reg_cid() walks the struct_ops member progs via
bpf_struct_ops_for_each_prog() and reads each prog's arena via
bpf_prog_arena(). The verifier enforces one arena per program, so each
member prog contributes at most one arena. All non-NULL contributions must
match and at least one member prog must use an arena. The map ref is held on
scx_sched and dropped on sched destroy. cpu-form schedulers (bpf_scx_reg)
are unchanged - no arena requirement.
Signed-off-by: Tejun Heo <tj@kernel.org>
Tejun Heo says:
====================
This makes BPF arena memory directly dereferenceable from kernel code
(struct_ops callbacks, kfuncs). Each arena gets a per-arena scratch page
that an arch fault hook installs into empty PTEs on kernel-side faults,
after KFENCE. The faulting instruction retries and the violation is reported
through the program's BPF stream.
v4:
- Patch 1: note that the strict-zero cmpxchg is narrower than pte_none() in
inline comments on both x86 and arm64. (Andrea)
- Patch 2: stub bpf_arena_handle_page_fault() for !CONFIG_BPF_SYSCALL via a
new include/linux/bpf_defs.h. (lkp)
- Patch 7: scx_arena_alloc() retries via a loop instead of a single retry on
pool growth. (Andrea)
- Picked up Reviewed-by tags from Emil and Andrea.
v3: https://lore.kernel.org/r/20260520235052.4180316-1-tj@kernel.org
v2: https://lore.kernel.org/r/20260517211232.1670594-1-tj@kernel.org
v1 (RFC): https://lore.kernel.org/r/20260427105109.2554518-1-tj@kernel.org
Motivation
----------
sched_ext's ops_cid.set_cmask() hands the BPF scheduler a struct scx_cmask
*. The kernel translates a kernel cpumask to a cmask, but it had no way to
write into the arena, so the cmask lived in kernel memory and was passed as
a trusted pointer. BPF cmask helpers all operate on arena cmasks though, so
the BPF side had to word-by-word probe-read the kernel cmask into an arena
cmask via cmask_copy_from_kernel() before any helper could touch it. It
works, but is clumsy.
The shape isn't unique to set_cmask. Sub-scheduler support is on the way and
more sched_ext callbacks will want to pass structured data to BPF. Anywhere
a kfunc or struct_ops callback wants to hand a struct to a BPF program,
arena residence is the natural answer.
Approach
--------
Each arena gets a per-arena scratch page. Arenas stay sparsely mapped as
today - PTEs are populated only for allocated pages. A new arch fault hook
(bpf_arena_handle_page_fault) is wired into x86 page_fault_oops() and arm64
__do_kernel_fault(), after KFENCE. When a kernel-side access faults inside
an arena's kern_vm range, the helper walks the stack to find the BPF program
responsible, range-checks the fault address against prog->aux->arena, and
atomically installs the scratch page into the empty PTE via the new
ptep_try_set() wrapper. The kernel instruction retries and reads/writes the
scratch page. Free paths and map destruction treat scratch as non-owned.
Real allocation refuses to overwrite scratch (apply_range_set_cb returns
-EBUSY). A scratched address stays dead until map destroy, since its
presence means the BPF program has already malfunctioned.
The mechanism is default behavior - no UAPI flag.
What this preserves
-------------------
All the debugging properties of today's sparse-PTE design are preserved:
* BPF programs still fault on unmapped arena accesses. The fault semantics
(instruction retry with rdst = 0) and the violation report through
bpf_streams are unchanged for prog-side accesses.
* The first kernel-side touch of an unmapped address is reported via
bpf_streams the same way as a prog-side fault, with the stack walk
attributing it to the originating prog.
* User-side fault on a never-scratched address still lazy-allocates a real
page (or returns SIGSEGV under BPF_F_SEGV_ON_FAULT). User-side fault on a
scratched address SIGSEGVs.
What changes for the kernel-side caller is just that an unmapped deref no
longer oopses - it retries through the scratch page and emits a violation
report. The same shape today's BPF instruction faults have.
Patches 1-2 (atomic PTE install + arena scratch-page recovery)
--------------------------------------------------------------
mm: Add ptep_try_set() for lockless empty-slot installs
bpf: Recover arena kernel faults with scratch page
Patches 3-5 (helpers used by struct_ops registration)
-----------------------------------------------------
bpf: Add sleepable variant of bpf_arena_alloc_pages for kernel callers
bpf: Add bpf_struct_ops_for_each_prog()
bpf/arena: Add bpf_arena_map_kern_vm_start() and bpf_prog_arena()
====================
Link: https://lore.kernel.org/bpf/20260522172219.1423324-1-tj@kernel.org/
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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Merge tag 'v7.1-rc5' into driver-core-next
We need the driver-core fixes in here as well to build on top of.
Signed-off-by: Danilo Krummrich <dakr@kernel.org>
The following scenarios will cause the call_rcu_tasks() boot-time
tests failed:
CPU0 CPU1
rcu_init_tasks_generic()
->rcu_tasks_initiate_self_tests()
->call_rcu_tasks_trace(&tests[1].rh, test_rcu_tasks_callback)
->call_rcu_tasks_generic()
->havekthread = smp_load_acquire(&rtp->kthread_ptr)
"The havekthread is false"
....
rcu_tasks_kthread()
->smp_store_release(&rtp->kthread_ptr, current)
->rcu_tasks_one_gp()
->rcuwait_wait_event()
->rcu_tasks_need_gpcb()
->for (cpu = 0; cpu < dequeue_limit; cpu++)
->rcu_segcblist_n_cbs(&rtpcp->cblist) == 0
->schedule()
->raw_spin_trylock_rcu_node()
->needwake = (func == wakeme_after_rcu) ||
(rcu_segcblist_n_cbs(&rtpcp->cblist) == rcu_task_lazy_lim)
"the rcu_task_lazy_lim default value is 32, and the
func pointer is test_rcu_tasks_callback, lead to needwake
is false."
->if (havekthread && !needwake && !timer_pending(&rtpcp->lazy_timer))
"the havekthread is false, will not enter here."
....
"the needwake is false lead to rtp_irq_work can not queue,
even if the rtp->kthread_ptr already exists at this point."
->if (needwake && READ_ONCE(rtp->kthread_ptr))
->irq_work_queue(&rtpcp->rtp_irq_work)
For the above scenarios, if the call_rcu_tasks() is not called again
afterward, the rcu_tasks_kthread will not have a chance to be wakeup,
the test_rcu_tasks_callback() will never be called, the boot-time tests
failed can happen, this commit therefore check havekthread variable, if
it's false and the rtpcp->cblist is empty, set needwake variable is true,
if the rtp->kthread_ptr exist, the rtpcp->rtp_irq_work can be queued to
wakeup rcu_tasks_kthread.
Signed-off-by: Zqiang <qiang.zhang@linux.dev>
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Currently, rcu_normal_wake_from_gp is only enabled by default
on small systems(<= 16 CPUs) or when a user explicitly set it
enabled.
Introduce an adaptive latching mechanism:
* Track the number of in-flight synchronize_rcu() requests
using a new rcu_sr_normal_count counter;
* If the count reaches/exceeds RCU_SR_NORMAL_LATCH_THR(64),
it sets the rcu_sr_normal_latched, reverting new requests
onto the scaled wait_rcu_gp() path;
* The latch is cleared only when the pending requests are fully
drained(nr == 0);
* Enables rcu_normal_wake_from_gp by default for all systems,
relying on this dynamic throttling instead of static CPU
limits.
Testing(synthetic flood workload):
* Kernel version: 6.19.0-rc6
* Number of CPUs: 1536
* 60K concurrent synchronize_rcu() calls
Perf(cycles, system-wide):
total cycles: 932020263832
rcu_sr_normal_add_req(): 2650282811 cycles(~0.28%)
Perf report excerpt:
0.01% 0.01% sync_test/... [k] rcu_sr_normal_add_req
Measured overhead of rcu_sr_normal_add_req() remained ~0.28%
of total CPU cycles in this synthetic stress test.
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Tested-by: Samir M <samir@linux.ibm.com>
Suggested-by: Joel Fernandes <joelagnelf@nvidia.com>
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
This commit replaces a nested ?: sequence with clamp_val(). 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 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>
