Bring in the shared branch with the kbuild tree to enable
'-fms-extensions' for 6.19. Further namespace cleanup work
requires this extension.
Signed-off-by: Christian Brauner <brauner@kernel.org>
cgroup_task_dead() is called from finish_task_switch() which runs with
preemption disabled and doesn't allow scheduling even on PREEMPT_RT. The
function needs to acquire css_set_lock which is a regular spinlock that can
sleep on RT kernels, leading to "sleeping function called from invalid
context" warnings.
css_set_lock is too large in scope to convert to a raw_spinlock. However,
the unlinking operations don't need to run synchronously - they just need
to complete after the task is done running.
On PREEMPT_RT, defer the work through irq_work. While the work doesn't need
to happen immediately, it can't be delayed indefinitely either as the dead
task pins the cgroup and task_struct can be pinned indefinitely. Use the
lazy version of irq_work to allow batching and lower impact while ensuring
timely completion.
v2: Use IRQ_WORK_INIT_LAZY instead of immediate irq_work and add explanation
for why the work can't be delayed indefinitely (Sebastian Andrzej Siewior).
Fixes: d245698d72 ("cgroup: Defer task cgroup unlink until after the task is done switching out")
Reported-by: Calvin Owens <calvin@wbinvd.org>
Link: https://lore.kernel.org/r/20251104181114.489391-1-calvin@wbinvd.org
Signed-off-by: Tejun Heo <tj@kernel.org>
The current cpuset code passes a local isolcpus_updated flag around in a
number of functions to determine if external isolation related cpumasks
like wq_unbound_cpumask should be updated. It is a bit cumbersome and
makes the code more complex. Simplify the code by using a global boolean
flag "isolated_cpus_updating" to track this. This flag will be set in
isolated_cpus_update() and cleared in update_isolation_cpumasks().
No functional change is expected.
Signed-off-by: Waiman Long <longman@redhat.com>
Reviewed-by: Chen Ridong <chenridong@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Commit 4a74e41888 ("cgroup/cpuset: Check partition conflict with
housekeeping setup") is supposed to ensure that domain isolated CPUs
designated by the "isolcpus" boot command line option stay either in
root partition or in isolated partitions. However, the required check
wasn't implemented when a remote partition was created or when an
existing partition changed type from "root" to "isolated".
Even though this is a relatively minor issue, we still need to add the
required prstate_housekeeping_conflict() call in the right places to
ensure that the rule is strictly followed.
The following steps can be used to reproduce the problem before this
fix.
# fmt -1 /proc/cmdline | grep isolcpus
isolcpus=9
# cd /sys/fs/cgroup/
# echo +cpuset > cgroup.subtree_control
# mkdir test
# echo 9 > test/cpuset.cpus
# echo isolated > test/cpuset.cpus.partition
# cat test/cpuset.cpus.partition
isolated
# cat test/cpuset.cpus.effective
9
# echo root > test/cpuset.cpus.partition
# cat test/cpuset.cpus.effective
9
# cat test/cpuset.cpus.partition
root
With this fix, the last few steps will become:
# echo root > test/cpuset.cpus.partition
# cat test/cpuset.cpus.effective
0-8,10-95
# cat test/cpuset.cpus.partition
root invalid (partition config conflicts with housekeeping setup)
Reported-by: Chen Ridong <chenridong@huawei.com>
Signed-off-by: Waiman Long <longman@redhat.com>
Reviewed-by: Chen Ridong <chenridong@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Move up the prstate_housekeeping_conflict() helper so that it can be
used in remote partition code.
Signed-off-by: Waiman Long <longman@redhat.com>
Reviewed-by: Chen Ridong <chenridong@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Currently the user can set up isolated cpus via cpuset and nohz_full in
such a way that leaves no housekeeping CPU (i.e. no CPU that is neither
domain isolated nor nohz full). This can be a problem for other
subsystems (e.g. the timer wheel imgration).
Prevent this configuration by blocking any assignation that would cause
the union of domain isolated cpus and nohz_full to covers all CPUs.
[longman: Remove isolated_cpus_should_update() and rewrite the checking
in update_prstate() and update_parent_effective_cpumask()]
Originally-by: Gabriele Monaco <gmonaco@redhat.com>
Signed-off-by: Waiman Long <longman@redhat.com>
Reviewed-by: Chen Ridong <chenridong@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
update_unbound_workqueue_cpumask() updates unbound workqueues settings
when there's a change in isolated CPUs, but it can be used for other
subsystems requiring updated when isolated CPUs change.
Generalise the name to update_isolation_cpumasks() to prepare for other
functions unrelated to workqueues to be called in that spot.
[longman: Change the function name to update_isolation_cpumasks()]
Acked-by: Frederic Weisbecker <frederic@kernel.org>
Acked-by: Waiman Long <longman@redhat.com>
Signed-off-by: Gabriele Monaco <gmonaco@redhat.com>
Signed-off-by: Waiman Long <longman@redhat.com>
Reviewed-by: Chen Ridong <chenridong@huaweicloud.com>
Reviewed-by: Chen Ridong <chenridong@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
When a task exits, css_set_move_task(tsk, cset, NULL, false) unlinks the task
from its cgroup. From the cgroup's perspective, the task is now gone. If this
makes the cgroup empty, it can be removed, triggering ->css_offline() callbacks
that notify controllers the cgroup is going offline resource-wise.
However, the exiting task can still run, perform memory operations, and schedule
until the final context switch in finish_task_switch(). This creates a confusing
situation where controllers are told a cgroup is offline while resource
activities are still happening in it. While this hasn't broken existing
controllers, it has caused direct confusion for sched_ext schedulers.
Split cgroup_task_exit() into two functions. cgroup_task_exit() now only calls
the subsystem exit callbacks and continues to be called from do_exit(). The
css_set cleanup is moved to the new cgroup_task_dead() which is called from
finish_task_switch() after the final context switch, so that the cgroup only
appears empty after the task is truly done running.
This also reorders operations so that subsys->exit() is now called before
unlinking from the cgroup, which shouldn't break anything.
Cc: Dan Schatzberg <dschatzberg@meta.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Tejun Heo <tj@kernel.org>
Currently, cgroup_task_exit() adds thread group leaders with live member
threads to their css_set's dying_tasks list (so cgroup.procs iteration can
still see the leader), and cgroup_task_release() later removes them with
list_del_init(&task->cg_list).
An upcoming patch will defer the dying_tasks list addition, moving it from
cgroup_task_exit() (called from do_exit()) to a new function called from
finish_task_switch(). However, release_task() (which calls
cgroup_task_release()) can run either before or after finish_task_switch(),
creating a race where cgroup_task_release() might try to remove the task from
dying_tasks before or while it's being added.
Move the list_del_init() from cgroup_task_release() to cgroup_task_free() to
fix this race. cgroup_task_free() runs from __put_task_struct(), which is
always after both paths, making the cleanup safe.
Cc: Dan Schatzberg <dschatzberg@meta.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Tejun Heo <tj@kernel.org>
The current names cgroup_exit(), cgroup_release(), and cgroup_free() are
confusing because they look like they're operating on cgroups themselves when
they're actually task lifecycle hooks. For example, cgroup_init() initializes
the cgroup subsystem while cgroup_exit() is a task exit notification to
cgroup. Rename them to cgroup_task_exit(), cgroup_task_release(), and
cgroup_task_free() to make it clear that these operate on tasks.
Cc: Dan Schatzberg <dschatzberg@meta.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Reviewed-by: Chen Ridong <chenridong@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
The current naming is very misleading as this really isn't exiting all
of the task's namespaces. It is only exiting the namespaces that hang of
off nsproxy. Reflect that in the name.
Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-10-2e6f823ebdc0@kernel.org
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
cgroup1 freezer piggybacks on the PM freezer, which inadvertently allowed
userspace to produce uninterruptible tasks at will. To avoid the issue,
cgroup2 freezer switched to a separate job control based mechanism. While
this happened a long time ago, the code and comment haven't been updated
making it confusing to people who aren't familiar with the history.
Rename cgroup_freezing() to cgroup1_freezing() and update comments on top of
freezing() and frozen() to clarify that cgroup2 freezer isn't covered by the
PM freezer mechanism.
Signed-off-by: Tejun Heo <tj@kernel.org>
Suggested-by: Qu Wenruo <wqu@suse.com>
Link: https://patch.msgid.link/aPZ3q6Hm865NicBC@slm.duckdns.org
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
The cpuset structure has a nr_subparts field which tracks the number
of child local partitions underneath a particular cpuset. Right now,
nr_subparts is only used in partition_is_populated() to avoid iteration
of child cpusets if the condition is right. So by always performing the
child iteration, we can avoid tracking the number of child partitions
and simplify the code a bit.
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
This pull request contains the following branches, non-octopus merged:
Documentation updates:
- Update whatisRCU.rst and checklist.rst for recent RCU API additions.
- Fix RCU documentation formatting and typos.
- Replace dead Ottawa Linux Symposium links in RTFP.txt.
Miscellaneous RCU updates:
- Document that rcu_barrier() hurries RCU_LAZY callbacks.
- Remove redundant interrupt disabling from
rcu_preempt_deferred_qs_handler().
- Move list_for_each_rcu from list.h to rculist.h, and adjust the
include directive in kernel/cgroup/dmem.c accordingly.
- Make initial set of changes to accommodate upcoming system_percpu_wq
changes.
SRCU updates:
- Create an srcu_read_lock_fast_notrace() for eventual use in tracing,
including adding guards.
- Document the reliance on per-CPU operations as implicit RCU readers
in __srcu_read_{,un}lock_fast().
- Document the srcu_flip() function's memory-barrier D's relationship
to SRCU-fast readers.
- Remove a redundant preempt_disable() and preempt_enable() pair from
srcu_gp_start_if_needed().
Torture-test updates:
- Fix jitter.sh spin time so that it actually varies as advertised.
It is still quite coarse-grained, but at least it does now vary.
- Update torture.sh help text to include the not-so-new --do-normal
parameter, which permits (for example) testing KCSAN kernels without
doing non-debug kernels.
- Fix a number of false-positive diagnostics that were being triggered
by rcutorture starting before boot completed. Running multiple
near-CPU-bound rcutorture processes when there is only the boot CPU
is after all a bit excessive.
- Substitute kcalloc() for kzalloc().
- Remove a redundant kfree() and NULL out kfree()ed objects.
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Merge tag 'rcu.2025.09.26a' of git://git.kernel.org/pub/scm/linux/kernel/git/rcu/linux
Pull RCU updates from Paul McKenney:
"Documentation updates:
- Update whatisRCU.rst and checklist.rst for recent RCU API additions
- Fix RCU documentation formatting and typos
- Replace dead Ottawa Linux Symposium links in RTFP.txt
Miscellaneous RCU updates:
- Document that rcu_barrier() hurries RCU_LAZY callbacks
- Remove redundant interrupt disabling from
rcu_preempt_deferred_qs_handler()
- Move list_for_each_rcu from list.h to rculist.h, and adjust the
include directive in kernel/cgroup/dmem.c accordingly
- Make initial set of changes to accommodate upcoming
system_percpu_wq changes
SRCU updates:
- Create an srcu_read_lock_fast_notrace() for eventual use in
tracing, including adding guards
- Document the reliance on per-CPU operations as implicit RCU readers
in __srcu_read_{,un}lock_fast()
- Document the srcu_flip() function's memory-barrier D's relationship
to SRCU-fast readers
- Remove a redundant preempt_disable() and preempt_enable() pair from
srcu_gp_start_if_needed()
Torture-test updates:
- Fix jitter.sh spin time so that it actually varies as advertised.
It is still quite coarse-grained, but at least it does now vary
- Update torture.sh help text to include the not-so-new --do-normal
parameter, which permits (for example) testing KCSAN kernels
without doing non-debug kernels
- Fix a number of false-positive diagnostics that were being
triggered by rcutorture starting before boot completed. Running
multiple near-CPU-bound rcutorture processes when there is only the
boot CPU is after all a bit excessive
- Substitute kcalloc() for kzalloc()
- Remove a redundant kfree() and NULL out kfree()ed objects"
* tag 'rcu.2025.09.26a' of git://git.kernel.org/pub/scm/linux/kernel/git/rcu/linux: (31 commits)
rcu: WQ_UNBOUND added to sync_wq workqueue
rcu: WQ_PERCPU added to alloc_workqueue users
rcu: replace use of system_wq with system_percpu_wq
refperf: Set reader_tasks to NULL after kfree()
refperf: Remove redundant kfree() after torture_stop_kthread()
srcu/tiny: Remove preempt_disable/enable() in srcu_gp_start_if_needed()
srcu: Document srcu_flip() memory-barrier D relation to SRCU-fast
srcu: Document __srcu_read_{,un}lock_fast() implicit RCU readers
rculist: move list_for_each_rcu() to where it belongs
refscale: Use kcalloc() instead of kzalloc()
rcutorture: Use kcalloc() instead of kzalloc()
docs: rcu: Replace multiple dead OLS links in RTFP.txt
doc: Fix typo in RCU's torture.rst documentation
Documentation: RCU: Retitle toctree index
Documentation: RCU: Reduce toctree depth
Documentation: RCU: Wrap kvm-remote.sh rerun snippet in literal code block
rcu: docs: Requirements.rst: Abide by conventions of kernel documentation
doc: Add RCU guards to checklist.rst
doc: Update whatisRCU.rst for recent RCU API additions
rcutorture: Delay forward-progress testing until boot completes
...
The commit afa3701c0e ("cgroup: cgroup.stat.local time accounting")
introduced a seqcount to track freeze timing but initialized it as a
plain seqcount_t using seqcount_init().
However, the write-side critical section in cgroup_do_freeze() holds
the css_set_lock spinlock while calling write_seqcount_begin(). On
PREEMPT_RT kernels, spinlocks do not disable preemption, causing the
lockdep assertion for a plain seqcount_t, which checks for preemption
being disabled, to fail.
This triggers the following warning:
WARNING: CPU: 0 PID: 9692 at include/linux/seqlock.h:221
Fix this by changing the type to seqcount_spinlock_t and initializing
it with seqcount_spinlock_init() to associate css_set_lock with the
seqcount. This allows lockdep to correctly validate that the spinlock
is held during write operations, resolving the assertion failure on all
kernel configurations.
Reported-by: syzbot+27a2519eb4dad86d0156@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=27a2519eb4dad86d0156
Fixes: afa3701c0e ("cgroup: cgroup.stat.local time accounting")
Signed-off-by: Nirbhay Sharma <nirbhay.lkd@gmail.com>
Link: https://lore.kernel.org/r/20251002165510.KtY3IT--@linutronix.de/
Acked-by: Michal Koutný <mkoutny@suse.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
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Merge tag 'bpf-next-6.18' of git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next
Pull bpf updates from Alexei Starovoitov:
- Support pulling non-linear xdp data with bpf_xdp_pull_data() kfunc
(Amery Hung)
Applied as a stable branch in bpf-next and net-next trees.
- Support reading skb metadata via bpf_dynptr (Jakub Sitnicki)
Also a stable branch in bpf-next and net-next trees.
- Enforce expected_attach_type for tailcall compatibility (Daniel
Borkmann)
- Replace path-sensitive with path-insensitive live stack analysis in
the verifier (Eduard Zingerman)
This is a significant change in the verification logic. More details,
motivation, long term plans are in the cover letter/merge commit.
- Support signed BPF programs (KP Singh)
This is another major feature that took years to materialize.
Algorithm details are in the cover letter/marge commit
- Add support for may_goto instruction to s390 JIT (Ilya Leoshkevich)
- Add support for may_goto instruction to arm64 JIT (Puranjay Mohan)
- Fix USDT SIB argument handling in libbpf (Jiawei Zhao)
- Allow uprobe-bpf program to change context registers (Jiri Olsa)
- Support signed loads from BPF arena (Kumar Kartikeya Dwivedi and
Puranjay Mohan)
- Allow access to union arguments in tracing programs (Leon Hwang)
- Optimize rcu_read_lock() + migrate_disable() combination where it's
used in BPF subsystem (Menglong Dong)
- Introduce bpf_task_work_schedule*() kfuncs to schedule deferred
execution of BPF callback in the context of a specific task using the
kernel’s task_work infrastructure (Mykyta Yatsenko)
- Enforce RCU protection for KF_RCU_PROTECTED kfuncs (Kumar Kartikeya
Dwivedi)
- Add stress test for rqspinlock in NMI (Kumar Kartikeya Dwivedi)
- Improve the precision of tnum multiplier verifier operation
(Nandakumar Edamana)
- Use tnums to improve is_branch_taken() logic (Paul Chaignon)
- Add support for atomic operations in arena in riscv JIT (Pu Lehui)
- Report arena faults to BPF error stream (Puranjay Mohan)
- Search for tracefs at /sys/kernel/tracing first in bpftool (Quentin
Monnet)
- Add bpf_strcasecmp() kfunc (Rong Tao)
- Support lookup_and_delete_elem command in BPF_MAP_STACK_TRACE (Tao
Chen)
* tag 'bpf-next-6.18' of git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next: (197 commits)
libbpf: Replace AF_ALG with open coded SHA-256
selftests/bpf: Add stress test for rqspinlock in NMI
selftests/bpf: Add test case for different expected_attach_type
bpf: Enforce expected_attach_type for tailcall compatibility
bpftool: Remove duplicate string.h header
bpf: Remove duplicate crypto/sha2.h header
libbpf: Fix error when st-prefix_ops and ops from differ btf
selftests/bpf: Test changing packet data from kfunc
selftests/bpf: Add stacktrace map lookup_and_delete_elem test case
selftests/bpf: Refactor stacktrace_map case with skeleton
bpf: Add lookup_and_delete_elem for BPF_MAP_STACK_TRACE
selftests/bpf: Fix flaky bpf_cookie selftest
selftests/bpf: Test changing packet data from global functions with a kfunc
bpf: Emit struct bpf_xdp_sock type in vmlinux BTF
selftests/bpf: Task_work selftest cleanup fixes
MAINTAINERS: Delete inactive maintainers from AF_XDP
bpf: Mark kfuncs as __noclone
selftests/bpf: Add kprobe multi write ctx attach test
selftests/bpf: Add kprobe write ctx attach test
selftests/bpf: Add uprobe context ip register change test
...
- Extensive cpuset code cleanup and refactoring work with no functional
changes: CPU mask computation logic refactoring, introducing new helpers,
removing redundant code paths, and improving error handling for better
maintainability.
- A few bug fixes to cpuset including fixes for partition creation failures
when isolcpus is in use, missing error returns, and null pointer access
prevention in free_tmpmasks().
- Core cgroup changes include replacing the global percpu_rwsem with
per-threadgroup rwsem when writing to cgroup.procs for better scalability,
workqueue conversions to use WQ_PERCPU and system_percpu_wq to prepare for
workqueue default switching from percpu to unbound, and removal of unused
code including the post_attach callback.
- New cgroup.stat.local time accounting feature that tracks frozen time
duration.
- Misc changes including selftests updates (new freezer time tests and
backward compatibility fixes), documentation sync, string function safety
improvements, and 64-bit division fixes.
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Merge tag 'cgroup-for-6.18' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup
Pull cgroup updates from Tejun Heo:
- Extensive cpuset code cleanup and refactoring work with no functional
changes: CPU mask computation logic refactoring, introducing new
helpers, removing redundant code paths, and improving error handling
for better maintainability.
- A few bug fixes to cpuset including fixes for partition creation
failures when isolcpus is in use, missing error returns, and null
pointer access prevention in free_tmpmasks().
- Core cgroup changes include replacing the global percpu_rwsem with
per-threadgroup rwsem when writing to cgroup.procs for better
scalability, workqueue conversions to use WQ_PERCPU and
system_percpu_wq to prepare for workqueue default switching from
percpu to unbound, and removal of unused code including the
post_attach callback.
- New cgroup.stat.local time accounting feature that tracks frozen time
duration.
- Misc changes including selftests updates (new freezer time tests and
backward compatibility fixes), documentation sync, string function
safety improvements, and 64-bit division fixes.
* tag 'cgroup-for-6.18' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup: (39 commits)
cpuset: remove is_prs_invalid helper
cpuset: remove impossible warning in update_parent_effective_cpumask
cpuset: remove redundant special case for null input in node mask update
cpuset: fix missing error return in update_cpumask
cpuset: Use new excpus for nocpu error check when enabling root partition
cpuset: fix failure to enable isolated partition when containing isolcpus
Documentation: cgroup-v2: Sync manual toctree
cpuset: use partition_cpus_change for setting exclusive cpus
cpuset: use parse_cpulist for setting cpus.exclusive
cpuset: introduce partition_cpus_change
cpuset: refactor cpus_allowed_validate_change
cpuset: refactor out validate_partition
cpuset: introduce cpus_excl_conflict and mems_excl_conflict helpers
cpuset: refactor CPU mask buffer parsing logic
cpuset: Refactor exclusive CPU mask computation logic
cpuset: change return type of is_partition_[in]valid to bool
cpuset: remove unused assignment to trialcs->partition_root_state
cpuset: move the root cpuset write check earlier
cgroup/cpuset: Remove redundant rcu_read_lock/unlock() in spin_lock
cgroup: Remove redundant rcu_read_lock/unlock() in spin_lock
...
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Merge tag 'namespace-6.18-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs
Pull namespace updates from Christian Brauner:
"This contains a larger set of changes around the generic namespace
infrastructure of the kernel.
Each specific namespace type (net, cgroup, mnt, ...) embedds a struct
ns_common which carries the reference count of the namespace and so
on.
We open-coded and cargo-culted so many quirks for each namespace type
that it just wasn't scalable anymore. So given there's a bunch of new
changes coming in that area I've started cleaning all of this up.
The core change is to make it possible to correctly initialize every
namespace uniformly and derive the correct initialization settings
from the type of the namespace such as namespace operations, namespace
type and so on. This leaves the new ns_common_init() function with a
single parameter which is the specific namespace type which derives
the correct parameters statically. This also means the compiler will
yell as soon as someone does something remotely fishy.
The ns_common_init() addition also allows us to remove ns_alloc_inum()
and drops any special-casing of the initial network namespace in the
network namespace initialization code that Linus complained about.
Another part is reworking the reference counting. The reference
counting was open-coded and copy-pasted for each namespace type even
though they all followed the same rules. This also removes all open
accesses to the reference count and makes it private and only uses a
very small set of dedicated helpers to manipulate them just like we do
for e.g., files.
In addition this generalizes the mount namespace iteration
infrastructure introduced a few cycles ago. As reminder, the vfs makes
it possible to iterate sequentially and bidirectionally through all
mount namespaces on the system or all mount namespaces that the caller
holds privilege over. This allow userspace to iterate over all mounts
in all mount namespaces using the listmount() and statmount() system
call.
Each mount namespace has a unique identifier for the lifetime of the
systems that is exposed to userspace. The network namespace also has a
unique identifier working exactly the same way. This extends the
concept to all other namespace types.
The new nstree type makes it possible to lookup namespaces purely by
their identifier and to walk the namespace list sequentially and
bidirectionally for all namespace types, allowing userspace to iterate
through all namespaces. Looking up namespaces in the namespace tree
works completely locklessly.
This also means we can move the mount namespace onto the generic
infrastructure and remove a bunch of code and members from struct
mnt_namespace itself.
There's a bunch of stuff coming on top of this in the future but for
now this uses the generic namespace tree to extend a concept
introduced first for pidfs a few cycles ago. For a while now we have
supported pidfs file handles for pidfds. This has proven to be very
useful.
This extends the concept to cover namespaces as well. It is possible
to encode and decode namespace file handles using the common
name_to_handle_at() and open_by_handle_at() apis.
As with pidfs file handles, namespace file handles are exhaustive,
meaning it is not required to actually hold a reference to nsfs in
able to decode aka open_by_handle_at() a namespace file handle.
Instead the FD_NSFS_ROOT constant can be passed which will let the
kernel grab a reference to the root of nsfs internally and thus decode
the file handle.
Namespaces file descriptors can already be derived from pidfds which
means they aren't subject to overmount protection bugs. IOW, it's
irrelevant if the caller would not have access to an appropriate
/proc/<pid>/ns/ directory as they could always just derive the
namespace based on a pidfd already.
It has the same advantage as pidfds. It's possible to reliably and for
the lifetime of the system refer to a namespace without pinning any
resources and to compare them trivially.
Permission checking is kept simple. If the caller is located in the
namespace the file handle refers to they are able to open it otherwise
they must hold privilege over the owning namespace of the relevant
namespace.
The namespace file handle layout is exposed as uapi and has a stable
and extensible format. For now it simply contains the namespace
identifier, the namespace type, and the inode number. The stable
format means that userspace may construct its own namespace file
handles without going through name_to_handle_at() as they are already
allowed for pidfs and cgroup file handles"
* tag 'namespace-6.18-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: (65 commits)
ns: drop assert
ns: move ns type into struct ns_common
nstree: make struct ns_tree private
ns: add ns_debug()
ns: simplify ns_common_init() further
cgroup: add missing ns_common include
ns: use inode initializer for initial namespaces
selftests/namespaces: verify initial namespace inode numbers
ns: rename to __ns_ref
nsfs: port to ns_ref_*() helpers
net: port to ns_ref_*() helpers
uts: port to ns_ref_*() helpers
ipv4: use check_net()
net: use check_net()
net-sysfs: use check_net()
user: port to ns_ref_*() helpers
time: port to ns_ref_*() helpers
pid: port to ns_ref_*() helpers
ipc: port to ns_ref_*() helpers
cgroup: port to ns_ref_*() helpers
...
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Merge tag 'kernel-6.18-rc1.clone3' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs
Pull copy_process updates from Christian Brauner:
"This contains the changes to enable support for clone3() on nios2
which apparently is still a thing.
The more exciting part of this is that it cleans up the inconsistency
in how the 64-bit flag argument is passed from copy_process() into the
various other copy_*() helpers"
[ Fixed up rv ltl_monitor 32-bit support as per Sasha Levin in the merge ]
* tag 'kernel-6.18-rc1.clone3' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
nios2: implement architecture-specific portion of sys_clone3
arch: copy_thread: pass clone_flags as u64
copy_process: pass clone_flags as u64 across calltree
copy_sighand: Handle architectures where sizeof(unsigned long) < sizeof(u64)
It's misplaced in struct proc_ns_operations and ns->ops might be NULL if
the namespace is compiled out but we still want to know the type of the
namespace for the initial namespace struct.
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>
The is_prs_invalid helper function is redundant as it serves a similar
purpose to is_partition_invalid. It can be fully replaced by the existing
is_partition_invalid function, so this patch removes the is_prs_invalid
helper.
Signed-off-by: Chen Ridong <chenridong@huawei.com>
Acked-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
If the parent is not a valid partition, an error will be returned before
any partition update command is processed. This means the
WARN_ON_ONCE(!is_partition_valid(parent)) can never be triggered, so
it is safe to remove.
Signed-off-by: Chen Ridong <chenridong@huawei.com>
Acked-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
The nodelist_parse function already handles empty nodemask input
appropriately, making it unnecessary to handle this case separately
during the node mask update process.
Signed-off-by: Chen Ridong <chenridong@huawei.com>
Reviewed-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Simply derive the ns operations from the namespace type.
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>
A previous patch fixed a bug where new_prs should be assigned before
checking housekeeping conflicts. This patch addresses another potential
issue: the nocpu error check currently uses the xcpus which is not updated.
Although no issue has been observed so far, the check should be performed
using the new effective exclusive cpus.
The comment has been removed because the function returns an error if
nocpu checking fails, which is unrelated to the parent.
Signed-off-by: Chen Ridong <chenridong@huawei.com>
Reviewed-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
The 'isolcpus' parameter specified at boot time can be assigned to an
isolated partition. While it is valid put the 'isolcpus' in an isolated
partition, attempting to change a member cpuset to an isolated partition
will fail if the cpuset contains any 'isolcpus'.
For example, the system boots with 'isolcpus=9', and the following
configuration works correctly:
# cd /sys/fs/cgroup/
# mkdir test
# echo 1 > test/cpuset.cpus
# echo isolated > test/cpuset.cpus.partition
# cat test/cpuset.cpus.partition
isolated
# echo 9 > test/cpuset.cpus
# cat test/cpuset.cpus.partition
isolated
# cat test/cpuset.cpus
9
However, the following steps to convert a member cpuset to an isolated
partition will fail:
# cd /sys/fs/cgroup/
# mkdir test
# echo 9 > test/cpuset.cpus
# echo isolated > test/cpuset.cpus.partition
# cat test/cpuset.cpus.partition
isolated invalid (partition config conflicts with housekeeping setup)
The issue occurs because the new partition state (new_prs) is used for
validation against housekeeping constraints before it has been properly
updated. To resolve this, move the assignment of new_prs before the
housekeeping validation check when enabling a root partition.
Fixes: 4a74e41888 ("cgroup/cpuset: Check partition conflict with housekeeping setup")
Signed-off-by: Chen Ridong <chenridong@huawei.com>
Reviewed-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
And drop ns_free_inum(). Anything common that can be wasted centrally
should be wasted in the new common helper.
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>
There's a lot of information that namespace implementers don't need to
know about at all. Encapsulate this all in the initialization helper.
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>
Every namespace type has a container_of(ns, <ns_type>, ns) static inline
function that is currently not exposed in the header. So we have a bunch
of places that open-code it via container_of(). Move it to the headers
so we can use it directly.
Reviewed-by: Aleksa Sarai <cyphar@cyphar.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
Support the generic ns lookup infrastructure to support file handles for
namespaces.
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
Don't cargo-cult the same thing over and over.
Acked-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>
A previous patch has introduced a new helper function
partition_cpus_change(). Now replace the exclusive cpus setting logic
with this helper function.
Signed-off-by: Chen Ridong <chenridong@huawei.com>
Reviewed-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Previous patches made parse_cpulist handle empty cpu mask input.
Now use this helper for exclusive cpus setting. Also, compute_trialcs_xcpus
can be called with empty cpus and handles it correctly.
Signed-off-by: Chen Ridong <chenridong@huawei.com>
Reviewed-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Introduce the partition_cpus_change function to handle both regular CPU
set updates and exclusive CPU modifications, either of which may trigger
partition state changes. This generalized function will also be utilized
for exclusive CPU updates in subsequent patches.
With the introduction of compute_trialcs_excpus in a previous patch,
the trialcs->effective_xcpus field is now consistently computed and
maintained. Consequently, the legacy logic which assigned
**trialcs->allowed_cpus to a local 'xcpus' variable** when
trialcs->effective_xcpus was empty has been removed.
This removal is safe because when trialcs is not a partition member,
trialcs->effective_xcpus is now correctly populated with the intersection
of user_xcpus and the parent's effective_xcpus. This calculation inherently
covers the scenario previously handled by the removed code.
Signed-off-by: Chen Ridong <chenridong@huawei.com>
Reviewed-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Refactor cpus_allowed_validate_change to handle the special case where
cpuset.cpus can be set even when violating partition sibling CPU
exclusivity rules. This differs from the general validation logic in
validate_change. Add a wrapper function to properly handle this
exceptional case.
The trialcs->prs_err field is cleared before performing validation checks
for both CPU changes and partition errors. If cpus_allowed_validate_change
fails its validation, trialcs->prs_err is set to PERR_NOTEXCL. If partition
validation fails, the specific error code returned by validate_partition
is assigned to trialcs->prs_err.
With the partition validation status now directly available through
trialcs->prs_err, the local boolean variable 'invalidate' becomes
redundant and can be safely removed.
Signed-off-by: Chen Ridong <chenridong@huawei.com>
Reviewed-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Refactor the validate_partition function to handle cpuset partition
validation when modifying cpuset.cpus. This refactoring also makes the
function reusable for handling cpuset.cpus.exclusive updates in subsequent
patches.
Signed-off-by: Chen Ridong <chenridong@huawei.com>
Reviewed-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
This patch adds cpus_excl_conflict() and mems_excl_conflict() helper
functions to improve code readability and maintainability. The exclusive
conflict checking follows these rules:
1. If either cpuset has the 'exclusive' flag set, their user_xcpus must
not have any overlap.
2. If neither cpuset has the 'exclusive' flag set, their
'cpuset.cpus.exclusive' (only for v2) values must not intersect.
3. The 'cpuset.cpus' of one cpuset must not form a subset of another
cpuset's 'cpuset.cpus.exclusive'.
Signed-off-by: Chen Ridong <chenridong@huawei.com>
Reviewed-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
The current implementation contains redundant handling for empty mask
inputs, as cpulist_parse() already properly handles these cases. This
refactoring introduces a new helper function parse_cpuset_cpulist() to
consolidate CPU list parsing logic and eliminate special-case checks for
empty inputs.
Additionally, the effective_xcpus computation for trial cpusets has been
simplified. Rather than computing effective_xcpus only when exclusive_cpus
is set or when the cpuset forms a valid partition, we now recalculate it
on every cpuset.cpus update. This approach ensures consistency and allows
removal of redundant effective_xcpus logic in subsequent patches.
The trial cpuset's effective_xcpus calculation follows two distinct cases:
1. For member cpusets: effective_xcpus is determined by the intersection
of cpuset->exclusive_cpus and the parent's effective_xcpus.
2. For non-member cpusets: effective_xcpus is derived from the intersection
of user_xcpus and the parent's effective_xcpus.
Signed-off-by: Chen Ridong <chenridong@huawei.com>
Reviewed-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
The current compute_effective_exclusive_cpumask function handles multiple
scenarios with different input parameters, making the code difficult to
follow. This patch refactors it into two separate functions:
compute_excpus and compute_trialcs_excpus.
The compute_excpus function calculates the exclusive CPU mask for a given
input and excludes exclusive CPUs from sibling cpusets when cs's
exclusive_cpus is not explicitly set.
The compute_trialcs_excpus function specifically handles exclusive CPU
computation for trial cpusets used during CPU mask configuration updates,
and always excludes exclusive CPUs from sibling cpusets.
This refactoring significantly improves code readability and clarity,
making it explicit which function to call for each use case and what
parameters should be provided.
Signed-off-by: Chen Ridong <chenridong@huawei.com>
Reviewed-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
The functions is_partition_valid() and is_partition_invalid() logically
return boolean values, but were previously declared with return type
'int'. This patch changes their return type to 'bool' to better reflect
their semantic meaning and improve type safety.
Signed-off-by: Chen Ridong <chenridong@huawei.com>
Reviewed-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
The trialcs->partition_root_state field is not used during the
configuration of 'cpuset.cpus' or 'cpuset.cpus.exclusive'. Therefore,
the assignment of values to this field can be safely removed.
Signed-off-by: Chen Ridong <chenridong@huawei.com>
Reviewed-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
The 'cpus' or 'mems' lists of the top_cpuset cannot be modified.
This check can be moved before acquiring any locks as a common code
block to improve efficiency and maintainability.
Signed-off-by: Chen Ridong <chenridong@huawei.com>
Reviewed-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Since commit a8bb74acd8 ("rcu: Consolidate RCU-sched update-side function definitions")
there is no difference between rcu_read_lock(), rcu_read_lock_bh() and
rcu_read_lock_sched() in terms of RCU read section and the relevant grace
period. That means that spin_lock(), which implies rcu_read_lock_sched(),
also implies rcu_read_lock().
There is no need no explicitly start a RCU read section if one has already
been started implicitly by spin_lock().
Simplify the code and remove the inner rcu_read_lock() invocation.
Cc: Waiman Long <longman@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Waiman Long <longman@redhat.com>
Signed-off-by: pengdonglin <pengdonglin@xiaomi.com>
Signed-off-by: pengdonglin <dolinux.peng@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Since commit a8bb74acd8 ("rcu: Consolidate RCU-sched update-side function definitions")
there is no difference between rcu_read_lock(), rcu_read_lock_bh() and
rcu_read_lock_sched() in terms of RCU read section and the relevant grace
period. That means that spin_lock(), which implies rcu_read_lock_sched(),
also implies rcu_read_lock().
There is no need no explicitly start a RCU read section if one has already
been started implicitly by spin_lock().
Simplify the code and remove the inner rcu_read_lock() invocation.
Cc: Tejun Heo <tj@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Waiman Long <longman@redhat.com>
Signed-off-by: pengdonglin <pengdonglin@xiaomi.com>
Signed-off-by: pengdonglin <dolinux.peng@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
The bpf_cgroup_from_id kfunc relies on cgroup_get_from_id to obtain the
cgroup corresponding to a given cgroup ID. This helper can be called in
a lot of contexts where the current thread can be random. A recent
example was its use in sched_ext's ops.tick(), to obtain the root cgroup
pointer. Since the current task can be whatever random user space task
preempted by the timer tick, this makes the behavior of the helper
unreliable.
Refactor out __cgroup_get_from_id as the non-namespace aware version of
cgroup_get_from_id, and change bpf_cgroup_from_id to make use of it.
There is no compatibility breakage here, since changing the namespace
against which the lookup is being done to the root cgroup namespace only
permits a wider set of lookups to succeed now. The cgroup IDs across
namespaces are globally unique, and thus don't need to be retranslated.
Reported-by: Dan Schatzberg <dschatzberg@meta.com>
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20250915032618.1551762-2-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
The static usage pattern of creating a cgroup, enabling controllers,
and then seeding it with CLONE_INTO_CGROUP doesn't require write
locking cgroup_threadgroup_rwsem and thus doesn't benefit from this
patch.
To avoid affecting other users, the per threadgroup rwsem is only used
when the favordynmods is enabled.
As computer hardware advances, modern systems are typically equipped
with many CPU cores and large amounts of memory, enabling the deployment
of numerous applications. On such systems, container creation and
deletion become frequent operations, making cgroup process migration no
longer a cold path. This leads to noticeable contention with common
process operations such as fork, exec, and exit.
To alleviate the contention between cgroup process migration and
operations like process fork, this patch modifies lock to take the write
lock on signal_struct->group_rwsem when writing pid to
cgroup.procs/threads instead of holding a global write lock.
Cgroup process migration has historically relied on
signal_struct->group_rwsem to protect thread group integrity. In commit
<1ed1328792ff> ("sched, cgroup: replace signal_struct->group_rwsem with
a global percpu_rwsem"), this was changed to a global
cgroup_threadgroup_rwsem. The advantage of using a global lock was
simplified handling of process group migrations. This patch retains the
use of the global lock for protecting process group migration, while
reducing contention by using per thread group lock during
cgroup.procs/threads writes.
The locking behavior is as follows:
write cgroup.procs/threads | process fork,exec,exit | process group migration
------------------------------------------------------------------------------
cgroup_lock() | down_read(&g_rwsem) | cgroup_lock()
down_write(&p_rwsem) | down_read(&p_rwsem) | down_write(&g_rwsem)
critical section | critical section | critical section
up_write(&p_rwsem) | up_read(&p_rwsem) | up_write(&g_rwsem)
cgroup_unlock() | up_read(&g_rwsem) | cgroup_unlock()
g_rwsem denotes cgroup_threadgroup_rwsem, p_rwsem denotes
signal_struct->group_rwsem.
This patch eliminates contention between cgroup migration and fork
operations for threads that belong to different thread groups, thereby
reducing the long-tail latency of cgroup migrations and lowering system
load.
With this patch, under heavy fork and exec interference, the long-tail
latency of cgroup migration has been reduced from milliseconds to
microseconds. Under heavy cgroup migration interference, the multi-CPU
score of the spawn test case in UnixBench increased by 9%.
tj: Update comment in cgroup_favor_dynmods() and switch WARN_ONCE() to
pr_warn_once().
Signed-off-by: Yi Tao <escape@linux.alibaba.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Later patches will introduce a new parameter `task` to
cgroup_attach_lock, thus adjusting the position of cgroup_attach_lock
within cgroup_procs_write_start.
Between obtaining the threadgroup leader via PID and acquiring the
cgroup attach lock, the threadgroup leader may change, which could lead
to incorrect cgroup migration. Therefore, after acquiring the cgroup
attach lock, we check whether the threadgroup leader has changed, and if
so, retry the operation.
tj: Minor comment adjustments.
Signed-off-by: Yi Tao <escape@linux.alibaba.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Dynamic cgroup migration involving threadgroup locks can be in one of
two states: no lock held, or holding the global lock. Explicitly
declaring the different lock modes to make the code easier to
understand and facilitates future extensions of the lock modes.
Signed-off-by: Yi Tao <escape@linux.alibaba.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Pull for-6.17-fixes to receive 79f919a89c ("cgroup: split
cgroup_destroy_wq into 3 workqueues") to resolve its conflict with
7fa33aa3b0 ("cgroup: WQ_PERCPU added to alloc_workqueue users"). The
latter adds WQ_PERCPU when creating cgroup_destroy_wq and the former splits
the workqueue into three. Resolve by applying WQ_PERCPU to the three split
workqueues.
Signed-off-by: Tejun Heo <tj@kernel.org>
Currently if a user enqueue a work item using schedule_delayed_work() the
used wq is "system_wq" (per-cpu wq) while queue_delayed_work() use
WORK_CPU_UNBOUND (used when a cpu is not specified). The same applies to
schedule_work() that is using system_wq and queue_work(), that makes use
again of WORK_CPU_UNBOUND.
This lack of consistentcy cannot be addressed without refactoring the API.
alloc_workqueue() treats all queues as per-CPU by default, while unbound
workqueues must opt-in via WQ_UNBOUND.
This default is suboptimal: most workloads benefit from unbound queues,
allowing the scheduler to place worker threads where they’re needed and
reducing noise when CPUs are isolated.
This patch adds a new WQ_PERCPU flag to explicitly request the use of
the per-CPU behavior. Both flags coexist for one release cycle to allow
callers to transition their calls.
Once migration is complete, WQ_UNBOUND can be removed and unbound will
become the implicit default.
With the introduction of the WQ_PERCPU flag (equivalent to !WQ_UNBOUND),
any alloc_workqueue() caller that doesn’t explicitly specify WQ_UNBOUND
must now use WQ_PERCPU.
All existing users have been updated accordingly.
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 if a user enqueue a work item using schedule_delayed_work() the
used wq is "system_wq" (per-cpu wq) while queue_delayed_work() use
WORK_CPU_UNBOUND (used when a cpu is not specified). The same applies to
schedule_work() that is using system_wq and queue_work(), that makes use
again of WORK_CPU_UNBOUND.
This lack of consistentcy cannot be addressed without refactoring the API.
system_wq is a per-CPU worqueue, yet nothing in its name tells about that
CPU affinity constraint, which is very often not required by users. Make
it clear by adding a system_percpu_wq.
queue_work() / queue_delayed_work() mod_delayed_work() will now use the
new per-cpu wq: whether the user still stick on the old name a warn will
be printed along a wq redirect to the new one.
This patch add the new system_percpu_wq except for mm, fs and net
subsystem, whom are handled in separated patches.
The old wq will be kept for a few release cylces.
Suggested-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Marco Crivellari <marco.crivellari@suse.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
d8b269e009 ("cgroup: Remove unused cgroup_subsys::post_attach") made $ss
and $ssid unused but didn't drop them leading to compilation warnings. Drop
them.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Chuyi Zhou <zhouchuyi@bytedance.com>
cgroup_subsys::post_attach callback was introduced in commit 5cf1cacb49
("cgroup, cpuset: replace cpuset_post_attach_flush() with
cgroup_subsys->post_attach callback") and only cpuset would use this
callback to wait for the mm migration to complete at the end of
__cgroup_procs_write(). Since the previous patch defer the flush operation
until returning to userspace, no one use this callback now. Remove this
callback from cgroup_subsys.
Signed-off-by: Chuyi Zhou <zhouchuyi@bytedance.com>
Acked-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Now in cpuset_attach(), we need to synchronously wait for
flush_workqueue to complete. The execution time of flushing
cpuset_migrate_mm_wq depends on the amount of mm migration initiated by
cpusets at that time. When the cpuset.mems of a cgroup occupying a large
amount of memory is modified, it may trigger extensive mm migration,
causing cpuset_attach() to block on flush_workqueue for an extended period.
This could be dangerous because cpuset_attach() is within the critical
section of cgroup_mutex, which may ultimately cause all cgroup-related
operations in the system to be blocked.
This patch attempts to defer the flush_workqueue() operation until
returning to userspace using the task_work which is originally proposed by
tejun[1], so that flush happens after cgroup_mutex is dropped. That way we
maintain the operation synchronicity while avoiding bothering anyone else.
[1]: https://lore.kernel.org/cgroups/ZgMFPMjZRZCsq9Q-@slm.duckdns.org/T/#m117f606fa24f66f0823a60f211b36f24bd9e1883
Originally-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Chuyi Zhou <zhouchuyi@bytedance.com>
Reviewed-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
It is unnecessary to always wait for the flush operation of
cpuset_migrate_mm_wq to complete in cpuset_write_resmask, as modifying
cpuset.cpus or cpuset.exclusive does not trigger mm migrations. The
flush_workqueue can be executed only when cpuset.mems is modified.
Signed-off-by: Chuyi Zhou <zhouchuyi@bytedance.com>
Reviewed-by: Michal Koutný <mkoutny@suse.com>
Reviewed-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Commit 5806b3d051 ("cpuset: decouple tmpmasks and cpumasks freeing in
cgroup") separates out the freeing of tmpmasks into a new free_tmpmask()
helper but removes the NULL pointer check in the process. Unfortunately a
NULL pointer can be passed to free_tmpmasks() in cpuset_handle_hotplug()
if cpuset v1 is active. This can cause segmentation fault and crash
the kernel.
Fix that by adding the NULL pointer check to free_tmpmasks().
Fixes: 5806b3d051 ("cpuset: decouple tmpmasks and cpumasks freeing in cgroup")
Reported-by: Ashay Jaiswal <quic_ashayj@quicinc.com>
Closes: https://lore.kernel.org/lkml/20250902-cpuset-free-on-condition-v1-1-f46ffab53eac@quicinc.com/
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
With the introduction of clone3 in commit 7f192e3cd3 ("fork: add
clone3") the effective bit width of clone_flags on all architectures was
increased from 32-bit to 64-bit, with a new type of u64 for the flags.
However, for most consumers of clone_flags the interface was not
changed from the previous type of unsigned long.
While this works fine as long as none of the new 64-bit flag bits
(CLONE_CLEAR_SIGHAND and CLONE_INTO_CGROUP) are evaluated, this is still
undesirable in terms of the principle of least surprise.
Thus, this commit fixes all relevant interfaces of callees to
sys_clone3/copy_process (excluding the architecture-specific
copy_thread) to consistently pass clone_flags as u64, so that
no truncation to 32-bit integers occurs on 32-bit architectures.
Signed-off-by: Simon Schuster <schuster.simon@siemens-energy.com>
Link: https://lore.kernel.org/20250901-nios2-implement-clone3-v2-2-53fcf5577d57@siemens-energy.com
Acked-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Christian Brauner <brauner@kernel.org>
cpuset: add helpers for cpus_read_lock and cpuset_mutex locks.
Replace repetitive locking patterns with new helpers:
- cpuset_full_lock()
- cpuset_full_unlock()
This makes the code cleaner and ensures consistent lock ordering.
Signed-off-by: Chen Ridong <chenridong@huawei.com>
Reviewed-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Currently, free_cpumasks() can free both tmpmasks and cpumasks of a cpuset
(cs). However, these two operations are not logically coupled. To improve
code clarity:
1. Move cpumask freeing to free_cpuset()
2. Rename free_cpumasks() to free_tmpmasks()
This change enforces the single responsibility principle.
Signed-off-by: Chen Ridong <chenridong@huawei.com>
Reviewed-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
The list_for_each_rcu() relies on the rcu_dereference() API which is not
provided by the list.h. At the same time list.h is a low-level basic header
that must not have dependencies like RCU, besides the fact of the potential
circular dependencies in some cases. With all that said, move RCU related
API to the rculist.h where it belongs.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Simona Vetter <simona.vetter@ffwll.ch>
Reviewed-by: "Paul E. McKenney" <paulmck@kernel.org>
Signed-off-by: Neeraj Upadhyay (AMD) <neeraj.upadhyay@kernel.org>
Signed-off-by: "Paul E. McKenney" <paulmck@kernel.org>
There isn't yet a clear way to identify a set of "lost" time that
everyone (or at least a wider group of users) cares about. However,
users can perform some delay accounting by iterating over components of
interest. This patch allows cgroup v2 freezing time to be one of those
components.
Track the cumulative time that each v2 cgroup spends freezing and expose
it to userland via a new local stat file in cgroupfs. Thank you to
Michal, who provided the ASCII art in the updated documentation.
To access this value:
$ mkdir /sys/fs/cgroup/test
$ cat /sys/fs/cgroup/test/cgroup.stat.local
freeze_time_total 0
Ensure consistent freeze time reads with freeze_seq, a per-cgroup
sequence counter. Writes are serialized using the css_set_lock.
Signed-off-by: Tiffany Yang <ynaffit@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Michal Koutný <mkoutny@suse.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
A hung task can occur during [1] LTP cgroup testing when repeatedly
mounting/unmounting perf_event and net_prio controllers with
systemd.unified_cgroup_hierarchy=1. The hang manifests in
cgroup_lock_and_drain_offline() during root destruction.
Related case:
cgroup_fj_function_perf_event cgroup_fj_function.sh perf_event
cgroup_fj_function_net_prio cgroup_fj_function.sh net_prio
Call Trace:
cgroup_lock_and_drain_offline+0x14c/0x1e8
cgroup_destroy_root+0x3c/0x2c0
css_free_rwork_fn+0x248/0x338
process_one_work+0x16c/0x3b8
worker_thread+0x22c/0x3b0
kthread+0xec/0x100
ret_from_fork+0x10/0x20
Root Cause:
CPU0 CPU1
mount perf_event umount net_prio
cgroup1_get_tree cgroup_kill_sb
rebind_subsystems // root destruction enqueues
// cgroup_destroy_wq
// kill all perf_event css
// one perf_event css A is dying
// css A offline enqueues cgroup_destroy_wq
// root destruction will be executed first
css_free_rwork_fn
cgroup_destroy_root
cgroup_lock_and_drain_offline
// some perf descendants are dying
// cgroup_destroy_wq max_active = 1
// waiting for css A to die
Problem scenario:
1. CPU0 mounts perf_event (rebind_subsystems)
2. CPU1 unmounts net_prio (cgroup_kill_sb), queuing root destruction work
3. A dying perf_event CSS gets queued for offline after root destruction
4. Root destruction waits for offline completion, but offline work is
blocked behind root destruction in cgroup_destroy_wq (max_active=1)
Solution:
Split cgroup_destroy_wq into three dedicated workqueues:
cgroup_offline_wq – Handles CSS offline operations
cgroup_release_wq – Manages resource release
cgroup_free_wq – Performs final memory deallocation
This separation eliminates blocking in the CSS free path while waiting for
offline operations to complete.
[1] https://github.com/linux-test-project/ltp/blob/master/runtest/controllers
Fixes: 334c3679ec ("cgroup: reimplement rebind_subsystems() using cgroup_apply_control() and friends")
Reported-by: Gao Yingjie <gaoyingjie@uniontech.com>
Signed-off-by: Chen Ridong <chenridong@huawei.com>
Suggested-by: Teju Heo <tj@kernel.org>
Signed-off-by: Tejun Heo <tj@kernel.org>
The CS_ONLINE flag was introduced prior to the CSS_ONLINE flag in the
cpuset subsystem. Currently, the flag setting sequence is as follows:
1. cpuset_css_online() sets CS_ONLINE
2. css->flags gets CSS_ONLINE set
...
3. cgroup->kill_css sets CSS_DYING
4. cpuset_css_offline() clears CS_ONLINE
5. css->flags clears CSS_ONLINE
The is_cpuset_online() check currently occurs between steps 1 and 3.
However, it would be equally safe to perform this check between steps 2
and 3, as CSS_ONLINE provides the same synchronization guarantee as
CS_ONLINE.
Since CS_ONLINE is redundant with CSS_ONLINE and provides no additional
synchronization benefits, we can safely remove it to simplify the code.
Signed-off-by: Chen Ridong <chenridong@huawei.com>
Acked-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
css_rstat_exit() may be called asynchronously in scenarios where preceding
calls to css_rstat_init() have not completed. One such example is this
sequence below:
css_create(...)
{
...
init_and_link_css(css, ...);
err = percpu_ref_init(...);
if (err)
goto err_free_css;
err = cgroup_idr_alloc(...);
if (err)
goto err_free_css;
err = css_rstat_init(css, ...);
if (err)
goto err_free_css;
...
err_free_css:
INIT_RCU_WORK(&css->destroy_rwork, css_free_rwork_fn);
queue_rcu_work(cgroup_destroy_wq, &css->destroy_rwork);
return ERR_PTR(err);
}
If any of the three goto jumps are taken, async cleanup will begin and
css_rstat_exit() will be invoked on an uninitialized css->rstat_cpu.
Avoid accessing the unitialized field by returning early in
css_rstat_exit() if this is the case.
Signed-off-by: JP Kobryn <inwardvessel@gmail.com>
Suggested-by: Michal Koutný <mkoutny@suse.com>
Fixes: 5da3bfa029 ("cgroup: use separate rstat trees for each subsystem")
Cc: stable@vger.kernel.org # v6.16
Reported-by: syzbot+8d052e8b99e40bc625ed@syzkaller.appspotmail.com
Acked-by: Shakeel Butt <shakeel.butt@linux.dev>
Signed-off-by: Tejun Heo <tj@kernel.org>
The css_get/put() calls in cpuset_partition_write() are unnecessary as
an active reference of the kernfs node will be taken which will prevent
its removal and guarantee the existence of the css. Only the online
check is needed.
Signed-off-by: Waiman Long <longman@redhat.com>
Reviewed-by: Michal Koutný <mkoutny@suse.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
It was found during testing that an invalid leaf partition with an
empty effective exclusive CPU list can become a valid empty partition
with no CPU afer an offline/online operation of an unrelated CPU. An
empty partition root is allowed in the special case that it has no
task in its cgroup and has distributed out all its CPUs to its child
partitions. That is certainly not the case here.
The problem is in the cpumask_subsets() test in the hotplug case
(update with no new mask) of update_parent_effective_cpumask() as it
also returns true if the effective exclusive CPU list is empty. Fix that
by addding the cpumask_empty() test to root out this exception case.
Also add the cpumask_empty() test in cpuset_hotplug_update_tasks()
to avoid calling update_parent_effective_cpumask() for this special case.
Fixes: 0c7f293efc ("cgroup/cpuset: Add cpuset.cpus.exclusive.effective for v2")
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
The following lockdep splat was observed.
[ 812.359086] ============================================
[ 812.359089] WARNING: possible recursive locking detected
[ 812.359097] --------------------------------------------
[ 812.359100] runtest.sh/30042 is trying to acquire lock:
[ 812.359105] ffffffffa7f27420 (cpu_hotplug_lock){++++}-{0:0}, at: static_key_enable+0xe/0x20
[ 812.359131]
[ 812.359131] but task is already holding lock:
[ 812.359134] ffffffffa7f27420 (cpu_hotplug_lock){++++}-{0:0}, at: cpuset_write_resmask+0x98/0xa70
:
[ 812.359267] Call Trace:
[ 812.359272] <TASK>
[ 812.359367] cpus_read_lock+0x3c/0xe0
[ 812.359382] static_key_enable+0xe/0x20
[ 812.359389] check_insane_mems_config.part.0+0x11/0x30
[ 812.359398] cpuset_write_resmask+0x9f2/0xa70
[ 812.359411] cgroup_file_write+0x1c7/0x660
[ 812.359467] kernfs_fop_write_iter+0x358/0x530
[ 812.359479] vfs_write+0xabe/0x1250
[ 812.359529] ksys_write+0xf9/0x1d0
[ 812.359558] do_syscall_64+0x5f/0xe0
Since commit d74b27d63a ("cgroup/cpuset: Change cpuset_rwsem
and hotplug lock order"), the ordering of cpu hotplug lock
and cpuset_mutex had been reversed. That patch correctly
used the cpuslocked version of the static branch API to enable
cpusets_pre_enable_key and cpusets_enabled_key, but it didn't do the
same for cpusets_insane_config_key.
The cpusets_insane_config_key can be enabled in the
check_insane_mems_config() which is called from update_nodemask()
or cpuset_hotplug_update_tasks() with both cpu hotplug lock and
cpuset_mutex held. Deadlock can happen with a pending hotplug event that
tries to acquire the cpu hotplug write lock which will block further
cpus_read_lock() attempt from check_insane_mems_config(). Fix that by
switching to use static_branch_enable_cpuslocked().
Fixes: d74b27d63a ("cgroup/cpuset: Change cpuset_rwsem and hotplug lock order")
Signed-off-by: Waiman Long <longman@redhat.com>
Reviewed-by: Juri Lelli <juri.lelli@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
- Allow css_rstat_updated() in NMI context to enable memory accounting for
allocations in NMI context.
- /proc/cgroups doesn't contain useful information for cgroup2 and was
updated to only show v1 controllers. This unfortunately broke something in
the wild. Add an option to bring back the old behavior to ease transition.
- selftest updates and other cleanups.
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Merge tag 'cgroup-for-6.17' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup
Pull cgroup updates from Tejun Heo:
- Allow css_rstat_updated() in NMI context to enable memory accounting
for allocations in NMI context.
- /proc/cgroups doesn't contain useful information for cgroup2 and was
updated to only show v1 controllers. This unfortunately broke
something in the wild. Add an option to bring back the old behavior
to ease transition.
- selftest updates and other cleanups.
* tag 'cgroup-for-6.17' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
cgroup: Add compatibility option for content of /proc/cgroups
selftests/cgroup: fix cpu.max tests
cgroup: llist: avoid memory tears for llist_node
selftests: cgroup: Fix missing newline in test_zswap_writeback_one
selftests: cgroup: Allow longer timeout for kmem_dead_cgroups cleanup
memcg: cgroup: call css_rstat_updated irrespective of in_nmi()
cgroup: remove per-cpu per-subsystem locks
cgroup: make css_rstat_updated nmi safe
cgroup: support to enable nmi-safe css_rstat_updated
selftests: cgroup: Fix compilation on pre-cgroupns kernels
selftests: cgroup: Optionally set up v1 environment
selftests: cgroup: Add support for named v1 hierarchies in test_core
selftests: cgroup_util: Add helpers for testing named v1 hierarchies
Documentation: cgroup: add section explaining controller availability
cgroup: Drop sock_cgroup_classid() dummy implementation
- The 4 patch series "mm: ksm: prevent KSM from breaking merging of new
VMAs" from Lorenzo Stoakes addresses an issue with KSM's
PR_SET_MEMORY_MERGE mode: newly mapped VMAs were not eligible for
merging with existing adjacent VMAs.
- The 4 patch series "mm/damon: introduce DAMON_STAT for simple and
practical access monitoring" from SeongJae Park adds a new kernel module
which simplifies the setup and usage of DAMON in production
environments.
- The 6 patch series "stop passing a writeback_control to swap/shmem
writeout" from Christoph Hellwig is a cleanup to the writeback code
which removes a couple of pointers from struct writeback_control.
- The 7 patch series "drivers/base/node.c: optimization and cleanups"
from Donet Tom contains largely uncorrelated cleanups to the NUMA node
setup and management code.
- The 4 patch series "mm: userfaultfd: assorted fixes and cleanups" from
Tal Zussman does some maintenance work on the userfaultfd code.
- The 5 patch series "Readahead tweaks for larger folios" from Ryan
Roberts implements some tuneups for pagecache readahead when it is
reading into order>0 folios.
- The 4 patch series "selftests/mm: Tweaks to the cow test" from Mark
Brown provides some cleanups and consistency improvements to the
selftests code.
- The 4 patch series "Optimize mremap() for large folios" from Dev Jain
does that. A 37% reduction in execution time was measured in a
memset+mremap+munmap microbenchmark.
- The 5 patch series "Remove zero_user()" from Matthew Wilcox expunges
zero_user() in favor of the more modern memzero_page().
- The 3 patch series "mm/huge_memory: vmf_insert_folio_*() and
vmf_insert_pfn_pud() fixes" from David Hildenbrand addresses some warts
which David noticed in the huge page code. These were not known to be
causing any issues at this time.
- The 3 patch series "mm/damon: use alloc_migrate_target() for
DAMOS_MIGRATE_{HOT,COLD" from SeongJae Park provides some cleanup and
consolidation work in DAMON.
- The 3 patch series "use vm_flags_t consistently" from Lorenzo Stoakes
uses vm_flags_t in places where we were inappropriately using other
types.
- The 3 patch series "mm/memfd: Reserve hugetlb folios before
allocation" from Vivek Kasireddy increases the reliability of large page
allocation in the memfd code.
- The 14 patch series "mm: Remove pXX_devmap page table bit and pfn_t
type" from Alistair Popple removes several now-unneeded PFN_* flags.
- The 5 patch series "mm/damon: decouple sysfs from core" from SeongJae
Park implememnts some cleanup and maintainability work in the DAMON
sysfs layer.
- The 5 patch series "madvise cleanup" from Lorenzo Stoakes does quite a
lot of cleanup/maintenance work in the madvise() code.
- The 4 patch series "madvise anon_name cleanups" from Vlastimil Babka
provides additional cleanups on top or Lorenzo's effort.
- The 11 patch series "Implement numa node notifier" from Oscar Salvador
creates a standalone notifier for NUMA node memory state changes.
Previously these were lumped under the more general memory on/offline
notifier.
- The 6 patch series "Make MIGRATE_ISOLATE a standalone bit" from Zi Yan
cleans up the pageblock isolation code and fixes a potential issue which
doesn't seem to cause any problems in practice.
- The 5 patch series "selftests/damon: add python and drgn based DAMON
sysfs functionality tests" from SeongJae Park adds additional drgn- and
python-based DAMON selftests which are more comprehensive than the
existing selftest suite.
- The 5 patch series "Misc rework on hugetlb faulting path" from Oscar
Salvador fixes a rather obscure deadlock in the hugetlb fault code and
follows that fix with a series of cleanups.
- The 3 patch series "cma: factor out allocation logic from
__cma_declare_contiguous_nid" from Mike Rapoport rationalizes and cleans
up the highmem-specific code in the CMA allocator.
- The 28 patch series "mm/migration: rework movable_ops page migration
(part 1)" from David Hildenbrand provides cleanups and
future-preparedness to the migration code.
- The 2 patch series "mm/damon: add trace events for auto-tuned
monitoring intervals and DAMOS quota" from SeongJae Park adds some
tracepoints to some DAMON auto-tuning code.
- The 6 patch series "mm/damon: fix misc bugs in DAMON modules" from
SeongJae Park does that.
- The 6 patch series "mm/damon: misc cleanups" from SeongJae Park also
does what it claims.
- The 4 patch series "mm: folio_pte_batch() improvements" from David
Hildenbrand cleans up the large folio PTE batching code.
- The 13 patch series "mm/damon/vaddr: Allow interleaving in
migrate_{hot,cold} actions" from SeongJae Park facilitates dynamic
alteration of DAMON's inter-node allocation policy.
- The 3 patch series "Remove unmap_and_put_page()" from Vishal Moola
provides a couple of page->folio conversions.
- The 4 patch series "mm: per-node proactive reclaim" from Davidlohr
Bueso implements a per-node control of proactive reclaim - beyond the
current memcg-based implementation.
- The 14 patch series "mm/damon: remove damon_callback" from SeongJae
Park replaces the damon_callback interface with a more general and
powerful damon_call()+damos_walk() interface.
- The 10 patch series "mm/mremap: permit mremap() move of multiple VMAs"
from Lorenzo Stoakes implements a number of mremap cleanups (of course)
in preparation for adding new mremap() functionality: newly permit the
remapping of multiple VMAs when the user is specifying MREMAP_FIXED. It
still excludes some specialized situations where this cannot be
performed reliably.
- The 3 patch series "drop hugetlb_free_pgd_range()" from Anthony Yznaga
switches some sparc hugetlb code over to the generic version and removes
the thus-unneeded hugetlb_free_pgd_range().
- The 4 patch series "mm/damon/sysfs: support periodic and automated
stats update" from SeongJae Park augments the present
userspace-requested update of DAMON sysfs monitoring files. Automatic
update is now provided, along with a tunable to control the update
interval.
- The 4 patch series "Some randome fixes and cleanups to swapfile" from
Kemeng Shi does what is claims.
- The 4 patch series "mm: introduce snapshot_page" from Luiz Capitulino
and David Hildenbrand provides (and uses) a means by which debug-style
functions can grab a copy of a pageframe and inspect it locklessly
without tripping over the races inherent in operating on the live
pageframe directly.
- The 6 patch series "use per-vma locks for /proc/pid/maps reads" from
Suren Baghdasaryan addresses the large contention issues which can be
triggered by reads from that procfs file. Latencies are reduced by more
than half in some situations. The series also introduces several new
selftests for the /proc/pid/maps interface.
- The 6 patch series "__folio_split() clean up" from Zi Yan cleans up
__folio_split()!
- The 7 patch series "Optimize mprotect() for large folios" from Dev
Jain provides some quite large (>3x) speedups to mprotect() when dealing
with large folios.
- The 2 patch series "selftests/mm: reuse FORCE_READ to replace "asm
volatile("" : "+r" (XXX));" and some cleanup" from wang lian does some
cleanup work in the selftests code.
- The 3 patch series "tools/testing: expand mremap testing" from Lorenzo
Stoakes extends the mremap() selftest in several ways, including adding
more checking of Lorenzo's recently added "permit mremap() move of
multiple VMAs" feature.
- The 22 patch series "selftests/damon/sysfs.py: test all parameters"
from SeongJae Park extends the DAMON sysfs interface selftest so that it
tests all possible user-requested parameters. Rather than the present
minimal subset.
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Merge tag 'mm-stable-2025-07-30-15-25' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Pull MM updates from Andrew Morton:
"As usual, many cleanups. The below blurbiage describes 42 patchsets.
21 of those are partially or fully cleanup work. "cleans up",
"cleanup", "maintainability", "rationalizes", etc.
I never knew the MM code was so dirty.
"mm: ksm: prevent KSM from breaking merging of new VMAs" (Lorenzo Stoakes)
addresses an issue with KSM's PR_SET_MEMORY_MERGE mode: newly
mapped VMAs were not eligible for merging with existing adjacent
VMAs.
"mm/damon: introduce DAMON_STAT for simple and practical access monitoring" (SeongJae Park)
adds a new kernel module which simplifies the setup and usage of
DAMON in production environments.
"stop passing a writeback_control to swap/shmem writeout" (Christoph Hellwig)
is a cleanup to the writeback code which removes a couple of
pointers from struct writeback_control.
"drivers/base/node.c: optimization and cleanups" (Donet Tom)
contains largely uncorrelated cleanups to the NUMA node setup and
management code.
"mm: userfaultfd: assorted fixes and cleanups" (Tal Zussman)
does some maintenance work on the userfaultfd code.
"Readahead tweaks for larger folios" (Ryan Roberts)
implements some tuneups for pagecache readahead when it is reading
into order>0 folios.
"selftests/mm: Tweaks to the cow test" (Mark Brown)
provides some cleanups and consistency improvements to the
selftests code.
"Optimize mremap() for large folios" (Dev Jain)
does that. A 37% reduction in execution time was measured in a
memset+mremap+munmap microbenchmark.
"Remove zero_user()" (Matthew Wilcox)
expunges zero_user() in favor of the more modern memzero_page().
"mm/huge_memory: vmf_insert_folio_*() and vmf_insert_pfn_pud() fixes" (David Hildenbrand)
addresses some warts which David noticed in the huge page code.
These were not known to be causing any issues at this time.
"mm/damon: use alloc_migrate_target() for DAMOS_MIGRATE_{HOT,COLD" (SeongJae Park)
provides some cleanup and consolidation work in DAMON.
"use vm_flags_t consistently" (Lorenzo Stoakes)
uses vm_flags_t in places where we were inappropriately using other
types.
"mm/memfd: Reserve hugetlb folios before allocation" (Vivek Kasireddy)
increases the reliability of large page allocation in the memfd
code.
"mm: Remove pXX_devmap page table bit and pfn_t type" (Alistair Popple)
removes several now-unneeded PFN_* flags.
"mm/damon: decouple sysfs from core" (SeongJae Park)
implememnts some cleanup and maintainability work in the DAMON
sysfs layer.
"madvise cleanup" (Lorenzo Stoakes)
does quite a lot of cleanup/maintenance work in the madvise() code.
"madvise anon_name cleanups" (Vlastimil Babka)
provides additional cleanups on top or Lorenzo's effort.
"Implement numa node notifier" (Oscar Salvador)
creates a standalone notifier for NUMA node memory state changes.
Previously these were lumped under the more general memory
on/offline notifier.
"Make MIGRATE_ISOLATE a standalone bit" (Zi Yan)
cleans up the pageblock isolation code and fixes a potential issue
which doesn't seem to cause any problems in practice.
"selftests/damon: add python and drgn based DAMON sysfs functionality tests" (SeongJae Park)
adds additional drgn- and python-based DAMON selftests which are
more comprehensive than the existing selftest suite.
"Misc rework on hugetlb faulting path" (Oscar Salvador)
fixes a rather obscure deadlock in the hugetlb fault code and
follows that fix with a series of cleanups.
"cma: factor out allocation logic from __cma_declare_contiguous_nid" (Mike Rapoport)
rationalizes and cleans up the highmem-specific code in the CMA
allocator.
"mm/migration: rework movable_ops page migration (part 1)" (David Hildenbrand)
provides cleanups and future-preparedness to the migration code.
"mm/damon: add trace events for auto-tuned monitoring intervals and DAMOS quota" (SeongJae Park)
adds some tracepoints to some DAMON auto-tuning code.
"mm/damon: fix misc bugs in DAMON modules" (SeongJae Park)
does that.
"mm/damon: misc cleanups" (SeongJae Park)
also does what it claims.
"mm: folio_pte_batch() improvements" (David Hildenbrand)
cleans up the large folio PTE batching code.
"mm/damon/vaddr: Allow interleaving in migrate_{hot,cold} actions" (SeongJae Park)
facilitates dynamic alteration of DAMON's inter-node allocation
policy.
"Remove unmap_and_put_page()" (Vishal Moola)
provides a couple of page->folio conversions.
"mm: per-node proactive reclaim" (Davidlohr Bueso)
implements a per-node control of proactive reclaim - beyond the
current memcg-based implementation.
"mm/damon: remove damon_callback" (SeongJae Park)
replaces the damon_callback interface with a more general and
powerful damon_call()+damos_walk() interface.
"mm/mremap: permit mremap() move of multiple VMAs" (Lorenzo Stoakes)
implements a number of mremap cleanups (of course) in preparation
for adding new mremap() functionality: newly permit the remapping
of multiple VMAs when the user is specifying MREMAP_FIXED. It still
excludes some specialized situations where this cannot be performed
reliably.
"drop hugetlb_free_pgd_range()" (Anthony Yznaga)
switches some sparc hugetlb code over to the generic version and
removes the thus-unneeded hugetlb_free_pgd_range().
"mm/damon/sysfs: support periodic and automated stats update" (SeongJae Park)
augments the present userspace-requested update of DAMON sysfs
monitoring files. Automatic update is now provided, along with a
tunable to control the update interval.
"Some randome fixes and cleanups to swapfile" (Kemeng Shi)
does what is claims.
"mm: introduce snapshot_page" (Luiz Capitulino and David Hildenbrand)
provides (and uses) a means by which debug-style functions can grab
a copy of a pageframe and inspect it locklessly without tripping
over the races inherent in operating on the live pageframe
directly.
"use per-vma locks for /proc/pid/maps reads" (Suren Baghdasaryan)
addresses the large contention issues which can be triggered by
reads from that procfs file. Latencies are reduced by more than
half in some situations. The series also introduces several new
selftests for the /proc/pid/maps interface.
"__folio_split() clean up" (Zi Yan)
cleans up __folio_split()!
"Optimize mprotect() for large folios" (Dev Jain)
provides some quite large (>3x) speedups to mprotect() when dealing
with large folios.
"selftests/mm: reuse FORCE_READ to replace "asm volatile("" : "+r" (XXX));" and some cleanup" (wang lian)
does some cleanup work in the selftests code.
"tools/testing: expand mremap testing" (Lorenzo Stoakes)
extends the mremap() selftest in several ways, including adding
more checking of Lorenzo's recently added "permit mremap() move of
multiple VMAs" feature.
"selftests/damon/sysfs.py: test all parameters" (SeongJae Park)
extends the DAMON sysfs interface selftest so that it tests all
possible user-requested parameters. Rather than the present minimal
subset"
* tag 'mm-stable-2025-07-30-15-25' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (370 commits)
MAINTAINERS: add missing headers to mempory policy & migration section
MAINTAINERS: add missing file to cgroup section
MAINTAINERS: add MM MISC section, add missing files to MISC and CORE
MAINTAINERS: add missing zsmalloc file
MAINTAINERS: add missing files to page alloc section
MAINTAINERS: add missing shrinker files
MAINTAINERS: move memremap.[ch] to hotplug section
MAINTAINERS: add missing mm_slot.h file THP section
MAINTAINERS: add missing interval_tree.c to memory mapping section
MAINTAINERS: add missing percpu-internal.h file to per-cpu section
mm/page_alloc: remove trace_mm_alloc_contig_migrate_range_info()
selftests/damon: introduce _common.sh to host shared function
selftests/damon/sysfs.py: test runtime reduction of DAMON parameters
selftests/damon/sysfs.py: test non-default parameters runtime commit
selftests/damon/sysfs.py: generalize DAMON context commit assertion
selftests/damon/sysfs.py: generalize monitoring attributes commit assertion
selftests/damon/sysfs.py: generalize DAMOS schemes commit assertion
selftests/damon/sysfs.py: test DAMOS filters commitment
selftests/damon/sysfs.py: generalize DAMOS scheme commit assertion
selftests/damon/sysfs.py: test DAMOS destinations commitment
...
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Merge tag 'bpf-next-6.17' of git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next
Pull bpf updates from Alexei Starovoitov:
- Remove usermode driver (UMD) framework (Thomas Weißschuh)
- Introduce Strongly Connected Component (SCC) in the verifier to
detect loops and refine register liveness (Eduard Zingerman)
- Allow 'void *' cast using bpf_rdonly_cast() and corresponding
'__arg_untrusted' for global function parameters (Eduard Zingerman)
- Improve precision for BPF_ADD and BPF_SUB operations in the verifier
(Harishankar Vishwanathan)
- Teach the verifier that constant pointer to a map cannot be NULL
(Ihor Solodrai)
- Introduce BPF streams for error reporting of various conditions
detected by BPF runtime (Kumar Kartikeya Dwivedi)
- Teach the verifier to insert runtime speculation barrier (lfence on
x86) to mitigate speculative execution instead of rejecting the
programs (Luis Gerhorst)
- Various improvements for 'veristat' (Mykyta Yatsenko)
- For CONFIG_DEBUG_KERNEL config warn on internal verifier errors to
improve bug detection by syzbot (Paul Chaignon)
- Support BPF private stack on arm64 (Puranjay Mohan)
- Introduce bpf_cgroup_read_xattr() kfunc to read xattr of cgroup's
node (Song Liu)
- Introduce kfuncs for read-only string opreations (Viktor Malik)
- Implement show_fdinfo() for bpf_links (Tao Chen)
- Reduce verifier's stack consumption (Yonghong Song)
- Implement mprog API for cgroup-bpf programs (Yonghong Song)
* tag 'bpf-next-6.17' of git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next: (192 commits)
selftests/bpf: Migrate fexit_noreturns case into tracing_failure test suite
selftests/bpf: Add selftest for attaching tracing programs to functions in deny list
bpf: Add log for attaching tracing programs to functions in deny list
bpf: Show precise rejected function when attaching fexit/fmod_ret to __noreturn functions
bpf: Fix various typos in verifier.c comments
bpf: Add third round of bounds deduction
selftests/bpf: Test invariants on JSLT crossing sign
selftests/bpf: Test cross-sign 64bits range refinement
selftests/bpf: Update reg_bound range refinement logic
bpf: Improve bounds when s64 crosses sign boundary
bpf: Simplify bounds refinement from s32
selftests/bpf: Enable private stack tests for arm64
bpf, arm64: JIT support for private stack
bpf: Move bpf_jit_get_prog_name() to core.c
bpf, arm64: Fix fp initialization for exception boundary
umd: Remove usermode driver framework
bpf/preload: Don't select USERMODE_DRIVER
selftests/bpf: Fix test dynptr/test_dynptr_memset_xdp_chunks failure
selftests/bpf: Fix test dynptr/test_dynptr_copy_xdp failure
selftests/bpf: Increase xdp data size for arm64 64K page size
...
An earlier commit to suppress a warning introduced a race condition where
tasks can escape cgroup1 freezer. Revert the commit and simply remove the
warning which was spurious to begin with.
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Merge tag 'cgroup-for-6.16-rc6-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup
Pull cgroup fixes from Tejun Heo:
"An earlier commit to suppress a warning introduced a race condition
where tasks can escape cgroup1 freezer. Revert the commit and simply
remove the warning which was spurious to begin with"
* tag 'cgroup-for-6.16-rc6-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
Revert "cgroup_freezer: cgroup_freezing: Check if not frozen"
sched,freezer: Remove unnecessary warning in __thaw_task
/proc/cgroups lists only v1 controllers by default, however, this is
only enforced since the commit af000ce852 ("cgroup: Do not report
unavailable v1 controllers in /proc/cgroups") and there is software in
the wild that uses content of /proc/cgroups to decide on availability of
v2 (sic) controllers.
Add a boottime param that can bring back the previous behavior for
setups where the check in the software cannot be changed and it causes
e.g. unintended OOMs.
Also, this patch takes out cgrp_v1_visible from cgroup1_subsys_absent()
guard since it's only important to check which hierarchy (v1 vs v2) the
subsys is attached to. This has no effect on the printed message but
the code is cleaner since cgrp_v1_visible is really about mounted
hierarchies, not the content of /proc/cgroups.
Link: https://lore.kernel.org/r/b26b60b7d0d2a5ecfd2f3c45f95f32922ed24686.camel@decadent.org.uk
Fixes: af000ce852 ("cgroup: Do not report unavailable v1 controllers in /proc/cgroups")
Fixes: a0ab145322 ("cgroup: Print message when /proc/cgroups is read on v2-only system")
Signed-off-by: Michal Koutný <mkoutny@suse.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
This reverts commit cff5f49d43.
Commit cff5f49d43 ("cgroup_freezer: cgroup_freezing: Check if not
frozen") modified the cgroup_freezing() logic to verify that the FROZEN
flag is not set, affecting the return value of the freezing() function,
in order to address a warning in __thaw_task.
A race condition exists that may allow tasks to escape being frozen. The
following scenario demonstrates this issue:
CPU 0 (get_signal path) CPU 1 (freezer.state reader)
try_to_freeze read freezer.state
__refrigerator freezer_read
update_if_frozen
WRITE_ONCE(current->__state, TASK_FROZEN);
...
/* Task is now marked frozen */
/* frozen(task) == true */
/* Assuming other tasks are frozen */
freezer->state |= CGROUP_FROZEN;
/* freezing(current) returns false */
/* because cgroup is frozen (not freezing) */
break out
__set_current_state(TASK_RUNNING);
/* Bug: Task resumes running when it should remain frozen */
The existing !frozen(p) check in __thaw_task makes the
WARN_ON_ONCE(freezing(p)) warning redundant. Removing this warning enables
reverting the commit cff5f49d43 ("cgroup_freezer: cgroup_freezing: Check
if not frozen") to resolve the issue.
The warning has been removed in the previous patch. This patch revert the
commit cff5f49d43 ("cgroup_freezer: cgroup_freezing: Check if not
frozen") to complete the fix.
Fixes: cff5f49d43 ("cgroup_freezer: cgroup_freezing: Check if not frozen")
Reported-by: Zhong Jiawei<zhongjiawei1@huawei.com>
Signed-off-by: Chen Ridong <chenridong@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Before the commit 36df6e3dbd ("cgroup: make css_rstat_updated nmi
safe"), the struct llist_node is expected to be private to the one
inserting the node to the lockless list or the one removing the node
from the lockless list. After the mentioned commit, the llist_node in
the rstat code is per-cpu shared between the stacked contexts i.e.
process, softirq, hardirq & nmi. It is possible the compiler may tear
the loads or stores of llist_node. Let's avoid that.
KCSAN reported the following race:
Reported by Kernel Concurrency Sanitizer on:
CPU: 60 UID: 0 PID: 5425 ... 6.16.0-rc3-next-20250626 #1 NONE
Tainted: [E]=UNSIGNED_MODULE
Hardware name: ...
==================================================================
==================================================================
BUG: KCSAN: data-race in css_rstat_flush / css_rstat_updated
write to 0xffffe8fffe1c85f0 of 8 bytes by task 1061 on cpu 1:
css_rstat_flush+0x1b8/0xeb0
__mem_cgroup_flush_stats+0x184/0x190
flush_memcg_stats_dwork+0x22/0x50
process_one_work+0x335/0x630
worker_thread+0x5f1/0x8a0
kthread+0x197/0x340
ret_from_fork+0xd3/0x110
ret_from_fork_asm+0x11/0x20
read to 0xffffe8fffe1c85f0 of 8 bytes by task 3551 on cpu 15:
css_rstat_updated+0x81/0x180
mod_memcg_lruvec_state+0x113/0x2d0
__mod_lruvec_state+0x3d/0x50
lru_add+0x21e/0x3f0
folio_batch_move_lru+0x80/0x1b0
__folio_batch_add_and_move+0xd7/0x160
folio_add_lru_vma+0x42/0x50
do_anonymous_page+0x892/0xe90
__handle_mm_fault+0xfaa/0x1520
handle_mm_fault+0xdc/0x350
do_user_addr_fault+0x1dc/0x650
exc_page_fault+0x5c/0x110
asm_exc_page_fault+0x22/0x30
value changed: 0xffffe8fffe18e0d0 -> 0xffffe8fffe1c85f0
$ ./scripts/faddr2line vmlinux css_rstat_flush+0x1b8/0xeb0
css_rstat_flush+0x1b8/0xeb0:
init_llist_node at include/linux/llist.h:86
(inlined by) llist_del_first_init at include/linux/llist.h:308
(inlined by) css_process_update_tree at kernel/cgroup/rstat.c:148
(inlined by) css_rstat_updated_list at kernel/cgroup/rstat.c:258
(inlined by) css_rstat_flush at kernel/cgroup/rstat.c:389
$ ./scripts/faddr2line vmlinux css_rstat_updated+0x81/0x180
css_rstat_updated+0x81/0x180:
css_rstat_updated at kernel/cgroup/rstat.c:90 (discriminator 1)
These are expected race and a simple READ_ONCE/WRITE_ONCE resolves these
reports. However let's add comments to explain the race and the need for
memory barriers if stronger guarantees are needed.
More specifically the rstat updater and the flusher can race and cause a
scenario where the stats updater skips adding the css to the lockless
list but the flusher might not see those updates done by the skipped
updater. This is benign race and the subsequent flusher will flush those
stats and at the moment there aren't any rstat users which are not fine
with this kind of race. However some future user might want more
stricter guarantee, so let's add appropriate comments to ease the job of
future users.
Signed-off-by: Shakeel Butt <shakeel.butt@linux.dev>
Reviewed-by: Paul E. McKenney <paulmck@kernel.org>
Fixes: 36df6e3dbd ("cgroup: make css_rstat_updated nmi safe")
Signed-off-by: Tejun Heo <tj@kernel.org>
cpuset is only concerned when a numa node changes its memory state, as it
needs to know the current numa nodes with memory to keep an updated
mems_allowed mask. So stop using the memory notifier and use the new numa
node notifer instead.
Link: https://lkml.kernel.org/r/20250616135158.450136-9-osalvador@suse.de
Signed-off-by: Oscar Salvador <osalvador@suse.de>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Harry Yoo <harry.yoo@oracle.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Cc: Rakie Kim <rakie.kim@sk.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cross-merge BPF, perf and other fixes after downstream PRs.
It restores BPF CI to green after critical fix
commit bc4394e5e7 ("perf: Fix the throttle error of some clock events")
No conflicts.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
In cgroup1 freezer, a task migrating into a frozen cgroup might not get
frozen immediately due to the wrong operation order. Fix it.
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Merge tag 'cgroup-for-6.16-rc2-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup
Pull cgroup fix from Tejun Heo:
- In cgroup1 freezer, a task migrating into a frozen cgroup might not
get frozen immediately due to the wrong operation order. Fix it.
* tag 'cgroup-for-6.16-rc2-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
cgroup,freezer: fix incomplete freezing when attaching tasks
An issue was found:
# cd /sys/fs/cgroup/freezer/
# mkdir test
# echo FROZEN > test/freezer.state
# cat test/freezer.state
FROZEN
# sleep 1000 &
[1] 863
# echo 863 > test/cgroup.procs
# cat test/freezer.state
FREEZING
When tasks are migrated to a frozen cgroup, the freezer fails to
immediately freeze the tasks, causing the cgroup to remain in the
"FREEZING".
The freeze_task() function is called before clearing the CGROUP_FROZEN
flag. This causes the freezing() check to incorrectly return false,
preventing __freeze_task() from being invoked for the migrated task.
To fix this issue, clear the CGROUP_FROZEN state before calling
freeze_task().
Fixes: f5d39b0208 ("freezer,sched: Rewrite core freezer logic")
Cc: stable@vger.kernel.org # v6.1+
Reported-by: Zhong Jiawei <zhongjiawei1@huawei.com>
Signed-off-by: Chen Ridong <chenridong@huawei.com>
Acked-by: Michal Koutný <mkoutny@suse.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
The rstat update side used to insert the cgroup whose stats are updated
in the update tree and the read side flush the update tree to get the
latest uptodate stats. The per-cpu per-subsystem locks were used to
synchronize the update and flush side. However now the update side does
not access update tree but uses per-cpu lockless lists. So there is no
need for locks to synchronize update and flush side. Let's remove them.
Suggested-by: JP Kobryn <inwardvessel@gmail.com>
Signed-off-by: Shakeel Butt <shakeel.butt@linux.dev>
Tested-by: JP Kobryn <inwardvessel@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
To make css_rstat_updated() able to safely run in nmi context, let's
move the rstat update tree creation at the flush side and use per-cpu
lockless lists in struct cgroup_subsys to track the css whose stats are
updated on that cpu.
The struct cgroup_subsys_state now has per-cpu lnode which needs to be
inserted into the corresponding per-cpu lhead of struct cgroup_subsys.
Since we want the insertion to be nmi safe, there can be multiple
inserters on the same cpu for the same lnode. Here multiple inserters
are from stacked contexts like softirq, hardirq and nmi.
The current llist does not provide function to protect against the
scenario where multiple inserters can use the same lnode. So, using
llist_node() out of the box is not safe for this scenario.
However we can protect against multiple inserters using the same lnode
by using the fact llist node points to itself when not on the llist and
atomically reset it and select the winner as the single inserter.
Signed-off-by: Shakeel Butt <shakeel.butt@linux.dev>
Tested-by: JP Kobryn <inwardvessel@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Add necessary infrastructure to enable the nmi-safe execution of
css_rstat_updated(). Currently css_rstat_updated() takes a per-cpu
per-css raw spinlock to add the given css in the per-cpu per-css update
tree. However the kernel can not spin in nmi context, so we need to
remove the spinning on the raw spinlock in css_rstat_updated().
To support lockless css_rstat_updated(), let's add necessary data
structures in the css and ss structures.
Signed-off-by: Shakeel Butt <shakeel.butt@linux.dev>
Tested-by: JP Kobryn <inwardvessel@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
One of key items in mprog API is revision for prog list. The revision
number will be increased if the prog list changed, e.g., attach, detach
or replace.
Add 'revisions' field to struct cgroup_bpf, representing revisions for
all cgroup related attachment types. The initial revision value is
set to 1, the same as kernel mprog implementations.
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20250606163136.2428732-1-yonghong.song@linux.dev
rstat per-subsystem split change skipped per-cpu allocation on UP configs;
however even on UP, depending on config options, the size of the percpu
struct may not be zero leading to crashes. Fix it by conditionalizing the
per-cpu area allocation and usage on the size of the per-cpu struct.
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Merge tag 'cgroup-for-6.16-rc1-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup
Pull cgroup fix from Tejun Heo:
"The rstat per-subsystem split change skipped per-cpu allocation on UP
configs; however even on UP, depending on config options, the size of
the percpu struct may not be zero leading to crashes.
Fix it by conditionalizing the per-cpu area allocation and usage on
the size of the per-cpu struct"
* tag 'cgroup-for-6.16-rc1-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
cgroup: adjust criteria for rstat subsystem cpu lock access
simplifies the act of creating a pte which addresses the first page in a
folio and reduces the amount of plumbing which architecture must
implement to provide this.
- The 8 patch series "Misc folio patches for 6.16" from Matthew Wilcox
is a shower of largely unrelated folio infrastructure changes which
clean things up and better prepare us for future work.
- The 3 patch series "memory,x86,acpi: hotplug memory alignment
advisement" from Gregory Price adds early-init code to prevent x86 from
leaving physical memory unused when physical address regions are not
aligned to memory block size.
- The 2 patch series "mm/compaction: allow more aggressive proactive
compaction" from Michal Clapinski provides some tuning of the (sadly,
hard-coded (more sadly, not auto-tuned)) thresholds for our invokation
of proactive compaction. In a simple test case, the reduction of a guest
VM's memory consumption was dramatic.
- The 8 patch series "Minor cleanups and improvements to swap freeing
code" from Kemeng Shi provides some code cleaups and a small efficiency
improvement to this part of our swap handling code.
- The 6 patch series "ptrace: introduce PTRACE_SET_SYSCALL_INFO API"
from Dmitry Levin adds the ability for a ptracer to modify syscalls
arguments. At this time we can alter only "system call information that
are used by strace system call tampering, namely, syscall number,
syscall arguments, and syscall return value.
This series should have been incorporated into mm.git's "non-MM"
branch, but I goofed.
- The 3 patch series "fs/proc: extend the PAGEMAP_SCAN ioctl to report
guard regions" from Andrei Vagin extends the info returned by the
PAGEMAP_SCAN ioctl against /proc/pid/pagemap. This permits CRIU to more
efficiently get at the info about guard regions.
- The 2 patch series "Fix parameter passed to page_mapcount_is_type()"
from Gavin Shan implements that fix. No runtime effect is expected
because validate_page_before_insert() happens to fix up this error.
- The 3 patch series "kernel/events/uprobes: uprobe_write_opcode()
rewrite" from David Hildenbrand basically brings uprobe text poking into
the current decade. Remove a bunch of hand-rolled implementation in
favor of using more current facilities.
- The 3 patch series "mm/ptdump: Drop assumption that pxd_val() is u64"
from Anshuman Khandual provides enhancements and generalizations to the
pte dumping code. This might be needed when 128-bit Page Table
Descriptors are enabled for ARM.
- The 12 patch series "Always call constructor for kernel page tables"
from Kevin Brodsky "ensures that the ctor/dtor is always called for
kernel pgtables, as it already is for user pgtables". This permits the
addition of more functionality such as "insert hooks to protect page
tables". This change does result in various architectures performing
unnecesary work, but this is fixed up where it is anticipated to occur.
- The 9 patch series "Rust support for mm_struct, vm_area_struct, and
mmap" from Alice Ryhl adds plumbing to permit Rust access to core MM
structures.
- The 3 patch series "fix incorrectly disallowed anonymous VMA merges"
from Lorenzo Stoakes takes advantage of some VMA merging opportunities
which we've been missing for 15 years.
- The 4 patch series "mm/madvise: batch tlb flushes for MADV_DONTNEED
and MADV_FREE" from SeongJae Park optimizes process_madvise()'s TLB
flushing. Instead of flushing each address range in the provided iovec,
we batch the flushing across all the iovec entries. The syscall's cost
was approximately halved with a microbenchmark which was designed to
load this particular operation.
- The 6 patch series "Track node vacancy to reduce worst case allocation
counts" from Sidhartha Kumar makes the maple tree smarter about its node
preallocation. stress-ng mmap performance increased by single-digit
percentages and the amount of unnecessarily preallocated memory was
dramaticelly reduced.
- The 3 patch series "mm/gup: Minor fix, cleanup and improvements" from
Baoquan He removes a few unnecessary things which Baoquan noted when
reading the code.
- The 3 patch series ""Enhance sysfs handling for memory hotplug in
weighted interleave" from Rakie Kim "enhances the weighted interleave
policy in the memory management subsystem by improving sysfs handling,
fixing memory leaks, and introducing dynamic sysfs updates for memory
hotplug support". Fixes things on error paths which we are unlikely to
hit.
- The 7 patch series "mm/damon: auto-tune DAMOS for NUMA setups
including tiered memory" from SeongJae Park introduces new DAMOS quota
goal metrics which eliminate the manual tuning which is required when
utilizing DAMON for memory tiering.
- The 5 patch series "mm/vmalloc.c: code cleanup and improvements" from
Baoquan He provides cleanups and small efficiency improvements which
Baoquan found via code inspection.
- The 2 patch series "vmscan: enforce mems_effective during demotion"
from Gregory Price "changes reclaim to respect cpuset.mems_effective
during demotion when possible". because "presently, reclaim explicitly
ignores cpuset.mems_effective when demoting, which may cause the cpuset
settings to violated." "This is useful for isolating workloads on a
multi-tenant system from certain classes of memory more consistently."
- The 2 patch series ""Clean up split_huge_pmd_locked() and remove
unnecessary folio pointers" from Gavin Guo provides minor cleanups and
efficiency gains in in the huge page splitting and migrating code.
- The 3 patch series "Use kmem_cache for memcg alloc" from Huan Yang
creates a slab cache for `struct mem_cgroup', yielding improved memory
utilization.
- The 4 patch series "add max arg to swappiness in memory.reclaim and
lru_gen" from Zhongkun He adds a new "max" argument to the "swappiness="
argument for memory.reclaim MGLRU's lru_gen. This directs proactive
reclaim to reclaim from only anon folios rather than file-backed folios.
- The 17 patch series "kexec: introduce Kexec HandOver (KHO)" from Mike
Rapoport is the first step on the path to permitting the kernel to
maintain existing VMs while replacing the host kernel via file-based
kexec. At this time only memblock's reserve_mem is preserved.
- The 7 patch series "mm: Introduce for_each_valid_pfn()" from David
Woodhouse provides and uses a smarter way of looping over a pfn range.
By skipping ranges of invalid pfns.
- The 2 patch series "sched/numa: Skip VMA scanning on memory pinned to
one NUMA node via cpuset.mems" from Libo Chen removes a lot of pointless
VMA scanning when a task is pinned a single NUMA mode. Dramatic
performance benefits were seen in some real world cases.
- The 2 patch series "JFS: Implement migrate_folio for
jfs_metapage_aops" from Shivank Garg addresses a warning which occurs
during memory compaction when using JFS.
- The 4 patch series "move all VMA allocation, freeing and duplication
logic to mm" from Lorenzo Stoakes moves some VMA code from kernel/fork.c
into the more appropriate mm/vma.c.
- The 6 patch series "mm, swap: clean up swap cache mapping helper" from
Kairui Song provides code consolidation and cleanups related to the
folio_index() function.
- The 2 patch series "mm/gup: Cleanup memfd_pin_folios()" from Vishal
Moola does that.
- The 8 patch series "memcg: Fix test_memcg_min/low test failures" from
Waiman Long addresses some bogus failures which are being reported by
the test_memcontrol selftest.
- The 3 patch series "eliminate mmap() retry merge, add .mmap_prepare
hook" from Lorenzo Stoakes commences the deprecation of
file_operations.mmap() in favor of the new
file_operations.mmap_prepare(). The latter is more restrictive and
prevents drivers from messing with things in ways which, amongst other
problems, may defeat VMA merging.
- The 4 patch series "memcg: decouple memcg and objcg stocks"" from
Shakeel Butt decouples the per-cpu memcg charge cache from the objcg's
one. This is a step along the way to making memcg and objcg charging
NMI-safe, which is a BPF requirement.
- The 6 patch series "mm/damon: minor fixups and improvements for code,
tests, and documents" from SeongJae Park is "yet another batch of
miscellaneous DAMON changes. Fix and improve minor problems in code,
tests and documents."
- The 7 patch series "memcg: make memcg stats irq safe" from Shakeel
Butt converts memcg stats to be irq safe. Another step along the way to
making memcg charging and stats updates NMI-safe, a BPF requirement.
- The 4 patch series "Let unmap_hugepage_range() and several related
functions take folio instead of page" from Fan Ni provides folio
conversions in the hugetlb code.
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Merge tag 'mm-stable-2025-05-31-14-50' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Pull MM updates from Andrew Morton:
- "Add folio_mk_pte()" from Matthew Wilcox simplifies the act of
creating a pte which addresses the first page in a folio and reduces
the amount of plumbing which architecture must implement to provide
this.
- "Misc folio patches for 6.16" from Matthew Wilcox is a shower of
largely unrelated folio infrastructure changes which clean things up
and better prepare us for future work.
- "memory,x86,acpi: hotplug memory alignment advisement" from Gregory
Price adds early-init code to prevent x86 from leaving physical
memory unused when physical address regions are not aligned to memory
block size.
- "mm/compaction: allow more aggressive proactive compaction" from
Michal Clapinski provides some tuning of the (sadly, hard-coded (more
sadly, not auto-tuned)) thresholds for our invokation of proactive
compaction. In a simple test case, the reduction of a guest VM's
memory consumption was dramatic.
- "Minor cleanups and improvements to swap freeing code" from Kemeng
Shi provides some code cleaups and a small efficiency improvement to
this part of our swap handling code.
- "ptrace: introduce PTRACE_SET_SYSCALL_INFO API" from Dmitry Levin
adds the ability for a ptracer to modify syscalls arguments. At this
time we can alter only "system call information that are used by
strace system call tampering, namely, syscall number, syscall
arguments, and syscall return value.
This series should have been incorporated into mm.git's "non-MM"
branch, but I goofed.
- "fs/proc: extend the PAGEMAP_SCAN ioctl to report guard regions" from
Andrei Vagin extends the info returned by the PAGEMAP_SCAN ioctl
against /proc/pid/pagemap. This permits CRIU to more efficiently get
at the info about guard regions.
- "Fix parameter passed to page_mapcount_is_type()" from Gavin Shan
implements that fix. No runtime effect is expected because
validate_page_before_insert() happens to fix up this error.
- "kernel/events/uprobes: uprobe_write_opcode() rewrite" from David
Hildenbrand basically brings uprobe text poking into the current
decade. Remove a bunch of hand-rolled implementation in favor of
using more current facilities.
- "mm/ptdump: Drop assumption that pxd_val() is u64" from Anshuman
Khandual provides enhancements and generalizations to the pte dumping
code. This might be needed when 128-bit Page Table Descriptors are
enabled for ARM.
- "Always call constructor for kernel page tables" from Kevin Brodsky
ensures that the ctor/dtor is always called for kernel pgtables, as
it already is for user pgtables.
This permits the addition of more functionality such as "insert hooks
to protect page tables". This change does result in various
architectures performing unnecesary work, but this is fixed up where
it is anticipated to occur.
- "Rust support for mm_struct, vm_area_struct, and mmap" from Alice
Ryhl adds plumbing to permit Rust access to core MM structures.
- "fix incorrectly disallowed anonymous VMA merges" from Lorenzo
Stoakes takes advantage of some VMA merging opportunities which we've
been missing for 15 years.
- "mm/madvise: batch tlb flushes for MADV_DONTNEED and MADV_FREE" from
SeongJae Park optimizes process_madvise()'s TLB flushing.
Instead of flushing each address range in the provided iovec, we
batch the flushing across all the iovec entries. The syscall's cost
was approximately halved with a microbenchmark which was designed to
load this particular operation.
- "Track node vacancy to reduce worst case allocation counts" from
Sidhartha Kumar makes the maple tree smarter about its node
preallocation.
stress-ng mmap performance increased by single-digit percentages and
the amount of unnecessarily preallocated memory was dramaticelly
reduced.
- "mm/gup: Minor fix, cleanup and improvements" from Baoquan He removes
a few unnecessary things which Baoquan noted when reading the code.
- ""Enhance sysfs handling for memory hotplug in weighted interleave"
from Rakie Kim "enhances the weighted interleave policy in the memory
management subsystem by improving sysfs handling, fixing memory
leaks, and introducing dynamic sysfs updates for memory hotplug
support". Fixes things on error paths which we are unlikely to hit.
- "mm/damon: auto-tune DAMOS for NUMA setups including tiered memory"
from SeongJae Park introduces new DAMOS quota goal metrics which
eliminate the manual tuning which is required when utilizing DAMON
for memory tiering.
- "mm/vmalloc.c: code cleanup and improvements" from Baoquan He
provides cleanups and small efficiency improvements which Baoquan
found via code inspection.
- "vmscan: enforce mems_effective during demotion" from Gregory Price
changes reclaim to respect cpuset.mems_effective during demotion when
possible. because presently, reclaim explicitly ignores
cpuset.mems_effective when demoting, which may cause the cpuset
settings to violated.
This is useful for isolating workloads on a multi-tenant system from
certain classes of memory more consistently.
- "Clean up split_huge_pmd_locked() and remove unnecessary folio
pointers" from Gavin Guo provides minor cleanups and efficiency gains
in in the huge page splitting and migrating code.
- "Use kmem_cache for memcg alloc" from Huan Yang creates a slab cache
for `struct mem_cgroup', yielding improved memory utilization.
- "add max arg to swappiness in memory.reclaim and lru_gen" from
Zhongkun He adds a new "max" argument to the "swappiness=" argument
for memory.reclaim MGLRU's lru_gen.
This directs proactive reclaim to reclaim from only anon folios
rather than file-backed folios.
- "kexec: introduce Kexec HandOver (KHO)" from Mike Rapoport is the
first step on the path to permitting the kernel to maintain existing
VMs while replacing the host kernel via file-based kexec. At this
time only memblock's reserve_mem is preserved.
- "mm: Introduce for_each_valid_pfn()" from David Woodhouse provides
and uses a smarter way of looping over a pfn range. By skipping
ranges of invalid pfns.
- "sched/numa: Skip VMA scanning on memory pinned to one NUMA node via
cpuset.mems" from Libo Chen removes a lot of pointless VMA scanning
when a task is pinned a single NUMA mode.
Dramatic performance benefits were seen in some real world cases.
- "JFS: Implement migrate_folio for jfs_metapage_aops" from Shivank
Garg addresses a warning which occurs during memory compaction when
using JFS.
- "move all VMA allocation, freeing and duplication logic to mm" from
Lorenzo Stoakes moves some VMA code from kernel/fork.c into the more
appropriate mm/vma.c.
- "mm, swap: clean up swap cache mapping helper" from Kairui Song
provides code consolidation and cleanups related to the folio_index()
function.
- "mm/gup: Cleanup memfd_pin_folios()" from Vishal Moola does that.
- "memcg: Fix test_memcg_min/low test failures" from Waiman Long
addresses some bogus failures which are being reported by the
test_memcontrol selftest.
- "eliminate mmap() retry merge, add .mmap_prepare hook" from Lorenzo
Stoakes commences the deprecation of file_operations.mmap() in favor
of the new file_operations.mmap_prepare().
The latter is more restrictive and prevents drivers from messing with
things in ways which, amongst other problems, may defeat VMA merging.
- "memcg: decouple memcg and objcg stocks"" from Shakeel Butt decouples
the per-cpu memcg charge cache from the objcg's one.
This is a step along the way to making memcg and objcg charging
NMI-safe, which is a BPF requirement.
- "mm/damon: minor fixups and improvements for code, tests, and
documents" from SeongJae Park is yet another batch of miscellaneous
DAMON changes. Fix and improve minor problems in code, tests and
documents.
- "memcg: make memcg stats irq safe" from Shakeel Butt converts memcg
stats to be irq safe. Another step along the way to making memcg
charging and stats updates NMI-safe, a BPF requirement.
- "Let unmap_hugepage_range() and several related functions take folio
instead of page" from Fan Ni provides folio conversions in the
hugetlb code.
* tag 'mm-stable-2025-05-31-14-50' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (285 commits)
mm: pcp: increase pcp->free_count threshold to trigger free_high
mm/hugetlb: convert use of struct page to folio in __unmap_hugepage_range()
mm/hugetlb: refactor __unmap_hugepage_range() to take folio instead of page
mm/hugetlb: refactor unmap_hugepage_range() to take folio instead of page
mm/hugetlb: pass folio instead of page to unmap_ref_private()
memcg: objcg stock trylock without irq disabling
memcg: no stock lock for cpu hot-unplug
memcg: make __mod_memcg_lruvec_state re-entrant safe against irqs
memcg: make count_memcg_events re-entrant safe against irqs
memcg: make mod_memcg_state re-entrant safe against irqs
memcg: move preempt disable to callers of memcg_rstat_updated
memcg: memcg_rstat_updated re-entrant safe against irqs
mm: khugepaged: decouple SHMEM and file folios' collapse
selftests/eventfd: correct test name and improve messages
alloc_tag: check mem_profiling_support in alloc_tag_init
Docs/damon: update titles and brief introductions to explain DAMOS
selftests/damon/_damon_sysfs: read tried regions directories in order
mm/damon/tests/core-kunit: add a test for damos_set_filters_default_reject()
mm/damon/paddr: remove unused variable, folio_list, in damon_pa_stat()
mm/damon/sysfs-schemes: fix wrong comment on damons_sysfs_quota_goal_metric_strs
...
Previously it was found that on uniprocessor machines the size of
raw_spinlock_t could be zero so a pre-processor conditional was used to
avoid the allocation of ss->rstat_ss_cpu_lock. The conditional did not take
into account cases where lock debugging features were enabled. Cover these
cases along with the original non-smp case by explicitly using the size of
size of the lock type as criteria for allocation/access where applicable.
Signed-off-by: JP Kobryn <inwardvessel@gmail.com>
Fixes: 748922dcfa "cgroup: use subsystem-specific rstat locks to avoid contention"
Reported-by: kernel test robot <oliver.sang@intel.com>
Closes: https://lore.kernel.org/oe-lkp/202505281034.7ae1668d-lkp@intel.com
Reviewed-by: Shakeel Butt <shakeel.butt@linux.dev>
Reviewed-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
* Add large stage-2 mapping (THP) support for non-protected guests when
pKVM is enabled, clawing back some performance.
* Enable nested virtualisation support on systems that support it,
though it is disabled by default.
* Add UBSAN support to the standalone EL2 object used in nVHE/hVHE and
protected modes.
* Large rework of the way KVM tracks architecture features and links
them with the effects of control bits. While this has no functional
impact, it ensures correctness of emulation (the data is automatically
extracted from the published JSON files), and helps dealing with the
evolution of the architecture.
* Significant changes to the way pKVM tracks ownership of pages,
avoiding page table walks by storing the state in the hypervisor's
vmemmap. This in turn enables the THP support described above.
* New selftest checking the pKVM ownership transition rules
* Fixes for FEAT_MTE_ASYNC being accidentally advertised to guests
even if the host didn't have it.
* Fixes for the address translation emulation, which happened to be
rather buggy in some specific contexts.
* Fixes for the PMU emulation in NV contexts, decoupling PMCR_EL0.N
from the number of counters exposed to a guest and addressing a
number of issues in the process.
* Add a new selftest for the SVE host state being corrupted by a
guest.
* Keep HCR_EL2.xMO set at all times for systems running with the
kernel at EL2, ensuring that the window for interrupts is slightly
bigger, and avoiding a pretty bad erratum on the AmpereOne HW.
* Add workaround for AmpereOne's erratum AC04_CPU_23, which suffers
from a pretty bad case of TLB corruption unless accesses to HCR_EL2
are heavily synchronised.
* Add a per-VM, per-ITS debugfs entry to dump the state of the ITS
tables in a human-friendly fashion.
* and the usual random cleanups.
LoongArch:
* Don't flush tlb if the host supports hardware page table walks.
* Add KVM selftests support.
RISC-V:
* Add vector registers to get-reg-list selftest
* VCPU reset related improvements
* Remove scounteren initialization from VCPU reset
* Support VCPU reset from userspace using set_mpstate() ioctl
x86:
* Initial support for TDX in KVM. This finally makes it possible to use the
TDX module to run confidential guests on Intel processors. This is quite a
large series, including support for private page tables (managed by the
TDX module and mirrored in KVM for efficiency), forwarding some TDVMCALLs
to userspace, and handling several special VM exits from the TDX module.
This has been in the works for literally years and it's not really possible
to describe everything here, so I'll defer to the various merge commits
up to and including commit 7bcf7246c4 ("Merge branch 'kvm-tdx-finish-initial'
into HEAD").
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Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm
Pull kvm updates from Paolo Bonzini:
"As far as x86 goes this pull request "only" includes TDX host support.
Quotes are appropriate because (at 6k lines and 100+ commits) it is
much bigger than the rest, which will come later this week and
consists mostly of bugfixes and selftests. s390 changes will also come
in the second batch.
ARM:
- Add large stage-2 mapping (THP) support for non-protected guests
when pKVM is enabled, clawing back some performance.
- Enable nested virtualisation support on systems that support it,
though it is disabled by default.
- Add UBSAN support to the standalone EL2 object used in nVHE/hVHE
and protected modes.
- Large rework of the way KVM tracks architecture features and links
them with the effects of control bits. While this has no functional
impact, it ensures correctness of emulation (the data is
automatically extracted from the published JSON files), and helps
dealing with the evolution of the architecture.
- Significant changes to the way pKVM tracks ownership of pages,
avoiding page table walks by storing the state in the hypervisor's
vmemmap. This in turn enables the THP support described above.
- New selftest checking the pKVM ownership transition rules
- Fixes for FEAT_MTE_ASYNC being accidentally advertised to guests
even if the host didn't have it.
- Fixes for the address translation emulation, which happened to be
rather buggy in some specific contexts.
- Fixes for the PMU emulation in NV contexts, decoupling PMCR_EL0.N
from the number of counters exposed to a guest and addressing a
number of issues in the process.
- Add a new selftest for the SVE host state being corrupted by a
guest.
- Keep HCR_EL2.xMO set at all times for systems running with the
kernel at EL2, ensuring that the window for interrupts is slightly
bigger, and avoiding a pretty bad erratum on the AmpereOne HW.
- Add workaround for AmpereOne's erratum AC04_CPU_23, which suffers
from a pretty bad case of TLB corruption unless accesses to HCR_EL2
are heavily synchronised.
- Add a per-VM, per-ITS debugfs entry to dump the state of the ITS
tables in a human-friendly fashion.
- and the usual random cleanups.
LoongArch:
- Don't flush tlb if the host supports hardware page table walks.
- Add KVM selftests support.
RISC-V:
- Add vector registers to get-reg-list selftest
- VCPU reset related improvements
- Remove scounteren initialization from VCPU reset
- Support VCPU reset from userspace using set_mpstate() ioctl
x86:
- Initial support for TDX in KVM.
This finally makes it possible to use the TDX module to run
confidential guests on Intel processors. This is quite a large
series, including support for private page tables (managed by the
TDX module and mirrored in KVM for efficiency), forwarding some
TDVMCALLs to userspace, and handling several special VM exits from
the TDX module.
This has been in the works for literally years and it's not really
possible to describe everything here, so I'll defer to the various
merge commits up to and including commit 7bcf7246c4 ('Merge
branch 'kvm-tdx-finish-initial' into HEAD')"
* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (248 commits)
x86/tdx: mark tdh_vp_enter() as __flatten
Documentation: virt/kvm: remove unreferenced footnote
RISC-V: KVM: lock the correct mp_state during reset
KVM: arm64: Fix documentation for vgic_its_iter_next()
KVM: arm64: np-guest CMOs with PMD_SIZE fixmap
KVM: arm64: Stage-2 huge mappings for np-guests
KVM: arm64: Add a range to pkvm_mappings
KVM: arm64: Convert pkvm_mappings to interval tree
KVM: arm64: Add a range to __pkvm_host_test_clear_young_guest()
KVM: arm64: Add a range to __pkvm_host_wrprotect_guest()
KVM: arm64: Add a range to __pkvm_host_unshare_guest()
KVM: arm64: Add a range to __pkvm_host_share_guest()
KVM: arm64: Introduce for_each_hyp_page
KVM: arm64: Handle huge mappings for np-guest CMOs
KVM: arm64: nv: Release faulted-in VNCR page from mmu_lock critical section
KVM: arm64: nv: Handle TLBI S1E2 for VNCR invalidation with mmu_lock held
KVM: arm64: nv: Hold mmu_lock when invalidating VNCR SW-TLB before translating
RISC-V: KVM: add KVM_CAP_RISCV_MP_STATE_RESET
RISC-V: KVM: Remove scounteren initialization
KVM: RISC-V: remove unnecessary SBI reset state
...
- cgroup rstat shared the tracking tree across all controlers with the
rationale being that a cgroup which is using one resource is likely to be
using other resources at the same time (ie. if something is allocating
memory, it's probably consuming CPU cycles). However, this turned out to
not scale very well especially with memcg using rstat for internal
operations which made memcg stat read and flush patterns substantially
different from other controllers. JP Kobryn split the rstat tree per
controller.
- cgroup BPF support was hooking into cgroup init/exit paths directly.
Convert them to use a notifier chain instead so that other usages can be
added easily. The two of the patches which implement this are mislabeled
as belonging to sched_ext instead of cgroup. Sorry.
- Relatively minor cpuset updates.
- Documentation updates.
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Merge tag 'cgroup-for-6.16' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup
Pull cgroup updates from Tejun Heo:
- cgroup rstat shared the tracking tree across all controllers with the
rationale being that a cgroup which is using one resource is likely
to be using other resources at the same time (ie. if something is
allocating memory, it's probably consuming CPU cycles).
However, this turned out to not scale very well especially with memcg
using rstat for internal operations which made memcg stat read and
flush patterns substantially different from other controllers. JP
Kobryn split the rstat tree per controller.
- cgroup BPF support was hooking into cgroup init/exit paths directly.
Convert them to use a notifier chain instead so that other usages can
be added easily. The two of the patches which implement this are
mislabeled as belonging to sched_ext instead of cgroup. Sorry.
- Relatively minor cpuset updates
- Documentation updates
* tag 'cgroup-for-6.16' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup: (23 commits)
sched_ext: Convert cgroup BPF support to use cgroup_lifetime_notifier
sched_ext: Introduce cgroup_lifetime_notifier
cgroup: Minor reorganization of cgroup_create()
cgroup, docs: cpu controller's interaction with various scheduling policies
cgroup, docs: convert space indentation to tab indentation
cgroup: avoid per-cpu allocation of size zero rstat cpu locks
cgroup, docs: be specific about bandwidth control of rt processes
cgroup: document the rstat per-cpu initialization
cgroup: helper for checking rstat participation of css
cgroup: use subsystem-specific rstat locks to avoid contention
cgroup: use separate rstat trees for each subsystem
cgroup: compare css to cgroup::self in helper for distingushing css
cgroup: warn on rstat usage by early init subsystems
cgroup/cpuset: drop useless cpumask_empty() in compute_effective_exclusive_cpumask()
cgroup/rstat: Improve cgroup_rstat_push_children() documentation
cgroup: fix goto ordering in cgroup_init()
cgroup: fix pointer check in css_rstat_init()
cgroup/cpuset: Add warnings to catch inconsistency in exclusive CPUs
cgroup/cpuset: Fix obsolete comment in cpuset_css_offline()
cgroup/cpuset: Always use cpu_active_mask
...
Other subsystems may make use of the cgroup hierarchy with the cgroup_bpf
support being one such example. For such a feature, it's useful to be able
to hook into cgroup creation and destruction paths to perform
feature-specific initializations and cleanups.
Add cgroup_lifetime_notifier which generates CGROUP_LIFETIME_ONLINE and
CGROUP_LIFETIME_OFFLINE events whenever cgroups are created and destroyed,
respectively.
The next patch will convert cgroup_bpf to use the new notifier and other
uses are planned.
Signed-off-by: Tejun Heo <tj@kernel.org>
cgroup_bpf init and exit handling will be moved to a notifier chain. In
prepartion, reorganize cgroup_create() a bit so that the new cgroup is fully
initialized before any outside changes are made.
- cgrp->ancestors[] initialization and the hierarchical nr_descendants and
nr_frozen_descendants updates were in the same loop. Separate them out and
do the former earlier and do the latter later.
- Relocate cgroup_bpf_inherit() call so that it's after all cgroup
initializations are complete.
No visible behavior changes expected.
Signed-off-by: Tejun Heo <tj@kernel.org>
Subsystem rstat locks are dynamically allocated per-cpu. It was discovered
that a panic can occur during this allocation when the lock size is zero.
This is the case on non-smp systems, since arch_spinlock_t is defined as an
empty struct. Prevent this allocation when !CONFIG_SMP by adding a
pre-processor conditional around the affected block.
Signed-off-by: JP Kobryn <inwardvessel@gmail.com>
Reported-by: Klara Modin <klarasmodin@gmail.com>
Fixes: 748922dcfa ("cgroup: use subsystem-specific rstat locks to avoid contention")
Signed-off-by: Tejun Heo <tj@kernel.org>
There are a few places where a conditional check is performed to validate a
given css on its rstat participation. This new helper tries to make the
code more readable where this check is performed.
Signed-off-by: JP Kobryn <inwardvessel@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
It is possible to eliminate contention between subsystems when
updating/flushing stats by using subsystem-specific locks. Let the existing
rstat locks be dedicated to the cgroup base stats and rename them to
reflect that. Add similar locks to the cgroup_subsys struct for use with
individual subsystems.
Lock initialization is done in the new function ss_rstat_init(ss) which
replaces cgroup_rstat_boot(void). If NULL is passed to this function, the
global base stat locks will be initialized. Otherwise, the subsystem locks
will be initialized.
Change the existing lock helper functions to accept a reference to a css.
Then within these functions, conditionally select the appropriate locks
based on the subsystem affiliation of the given css. Add helper functions
for this selection routine to avoid repeated code.
Signed-off-by: JP Kobryn <inwardvessel@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Different subsystems may call cgroup_rstat_updated() within the same
cgroup, resulting in a tree of pending updates from multiple subsystems.
When one of these subsystems is flushed via cgroup_rstat_flushed(), all
other subsystems with pending updates on the tree will also be flushed.
Change the paradigm of having a single rstat tree for all subsystems to
having separate trees for each subsystem. This separation allows for
subsystems to perform flushes without the side effects of other subsystems.
As an example, flushing the cpu stats will no longer cause the memory stats
to be flushed and vice versa.
In order to achieve subsystem-specific trees, change the tree node type
from cgroup to cgroup_subsys_state pointer. Then remove those pointers from
the cgroup and instead place them on the css. Finally, change update/flush
functions to make use of the different node type (css). These changes allow
a specific subsystem to be associated with an update or flush. Separate
rstat trees will now exist for each unique subsystem.
Since updating/flushing will now be done at the subsystem level, there is
no longer a need to keep track of updated css nodes at the cgroup level.
The list management of these nodes done within the cgroup (rstat_css_list
and related) has been removed accordingly.
Conditional guards for checking validity of a given css were placed within
css_rstat_updated/flush() to prevent undefined behavior occuring from kfunc
usage in bpf programs. Guards were also placed within css_rstat_init/exit()
in order to help consolidate calls to them. At call sites for all four
functions, the existing guards were removed.
Signed-off-by: JP Kobryn <inwardvessel@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Adjust the implementation of css_is_cgroup() so that it compares the given
css to cgroup::self. Rename the function to css_is_self() in order to
reflect that. Change the existing css->ss NULL check to a warning in the
true branch. Finally, adjust call sites to use the new function name.
Signed-off-by: JP Kobryn <inwardvessel@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
An early init subsystem that attempts to make use of rstat can lead to
failures during early boot. The reason for this is the timing in which the
css's of the root cgroup have css_online() invoked on them. At the point of
this call, there is a stated assumption that a cgroup has "successfully
completed all allocations" [0]. An example of a subsystem that relies on
the previously mentioned assumption [0] is the memory subsystem. Within its
implementation of css_online(), work is queued to asynchronously begin
flushing via rstat. In the early init path for a given subsystem, having
rstat enabled leads to this sequence:
cgroup_init_early()
for_each_subsys(ss, ssid)
if (ss->early_init)
cgroup_init_subsys(ss, true)
cgroup_init_subsys(ss, early_init)
css = ss->css_alloc(...)
init_and_link_css(css, ss, ...)
...
online_css(css)
online_css(css)
ss = css->ss
ss->css_online(css)
Continuing to use the memory subsystem as an example, the issue with this
sequence is that css_rstat_init() has not been called yet. This means there
is now a race between the pending async work to flush rstat and the call to
css_rstat_init(). So a flush can occur within the given cgroup while the
rstat fields are not initialized.
Since we are in the early init phase, the rstat fields cannot be
initialized because they require per-cpu allocations. So it's not possible
to have css_rstat_init() called early enough (before online_css()). This
patch treats the combination of early init and rstat the same as as other
invalid conditions.
[0] Documentation/admin-guide/cgroup-v1/cgroups.rst (section: css_online)
Signed-off-by: JP Kobryn <inwardvessel@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
It is possible for a reclaimer to cause demotions of an lruvec belonging
to a cgroup with cpuset.mems set to exclude some nodes. Attempt to apply
this limitation based on the lruvec's memcg and prevent demotion.
Notably, this may still allow demotion of shared libraries or any memory
first instantiated in another cgroup. This means cpusets still cannot
cannot guarantee complete isolation when demotion is enabled, and the docs
have been updated to reflect this.
This is useful for isolating workloads on a multi-tenant system from
certain classes of memory more consistently - with the noted exceptions.
Note on locking:
The cgroup_get_e_css reference protects the css->effective_mems, and calls
of this interface would be subject to the same race conditions associated
with a non-atomic access to cs->effective_mems.
So while this interface cannot make strong guarantees of correctness, it
can therefore avoid taking a global or rcu_read_lock for performance.
Link: https://lkml.kernel.org/r/20250424202806.52632-3-gourry@gourry.net
Signed-off-by: Gregory Price <gourry@gourry.net>
Suggested-by: Shakeel Butt <shakeel.butt@linux.dev>
Suggested-by: Waiman Long <longman@redhat.com>
Acked-by: Tejun Heo <tj@kernel.org>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Shakeel Butt <shakeel.butt@linux.dev>
Reviewed-by: Waiman Long <longman@redhat.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Michal Koutný <mkoutny@suse.com>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Patch series "vmscan: enforce mems_effective during demotion", v5.
Change reclaim to respect cpuset.mems_effective during demotion when
possible. Presently, reclaim explicitly ignores cpuset.mems_effective
when demoting, which may cause the cpuset settings to violated.
Implement cpuset_node_allowed() to check the cpuset.mems_effective
associated wih the mem_cgroup of the lruvec being scanned. This only
applies to cgroup/cpuset v2, as cpuset exists in a different hierarchy
than mem_cgroup in v1.
This requires renaming the existing cpuset_node_allowed() to be
cpuset_current_now_allowed() - which is more descriptive anyway - to
implement the new cpuset_node_allowed() which takes a target cgroup.
This patch (of 2):
Rename cpuset_node_allowed to reflect that the function checks the current
task's cpuset.mems. This allows us to make a new cpuset_node_allowed
function that checks a target cgroup's cpuset.mems.
Link: https://lkml.kernel.org/r/20250424202806.52632-1-gourry@gourry.net
Link: https://lkml.kernel.org/r/20250424202806.52632-2-gourry@gourry.net
Signed-off-by: Gregory Price <gourry@gourry.net>
Acked-by: Waiman Long <longman@redhat.com>
Acked-by: Tejun Heo <tj@kernel.org>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Michal Koutný <mkoutny@suse.com>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Commit ec5fbdfb99 ("cgroup/cpuset: Enable update_tasks_cpumask()
on top_cpuset") enabled us to pull CPUs dedicated to child partitions
from tasks in top_cpuset by ignoring per cpu kthreads. However, there
can be other kthreads that are not per cpu but have PF_NO_SETAFFINITY
flag set to indicate that we shouldn't mess with their CPU affinity.
For other kthreads, their affinity will be changed to skip CPUs dedicated
to child partitions whether it is an isolating or a scheduling one.
As all the per cpu kthreads have PF_NO_SETAFFINITY set, the
PF_NO_SETAFFINITY tasks are essentially a superset of per cpu kthreads.
Fix this issue by dropping the kthread_is_per_cpu() check and checking
the PF_NO_SETAFFINITY flag instead.
Fixes: ec5fbdfb99 ("cgroup/cpuset: Enable update_tasks_cpumask() on top_cpuset")
Signed-off-by: Waiman Long <longman@redhat.com>
Acked-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Tejun Heo <tj@kernel.org>
Empty cpumasks can't intersect with any others. Therefore, testing for
non-emptyness is useless.
Signed-off-by: Yury Norov <yury.norov@gmail.com>
Reviewed-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
The cgroup_rstat_push_children() function converts a set of
updated_children lists from different cgroups into a single ordered
list of cgroups to be flushed via the rstat_flush_next pointer.
The algorithm used isn't that well illustrated and it takes time to
grasp what it is doing. Improve the embedded documentation and variable
names to better illustrate the transformation process and make the code
easier to understand.
Also cgroup_rstat_lock must be held for the whole duration
from where the rstat_flush_next list is being constructed in
cgroup_rstat_push_children() to when it is consumed later in
css_rstat_flush(). Otherwise, list corruption can happen leading to
system crash as reported in [1]. In this particular case, the branch
being used has commit 093c8812de ("cgroup: rstat: Cleanup flushing
functions and locking") which breaks this rule, but is missing the fix
commit 7d6c63c319 ("cgroup: rstat: call cgroup_rstat_updated_list
with cgroup_rstat_lock") that fixes it.
This patch has no functional change.
[1] https://lore.kernel.org/lkml/BY5PR04MB68495E9E8A46CA9614D62669BCBB2@BY5PR04MB6849.namprd04.prod.outlook.com/
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Go to the appropriate section labels when css_rstat_init() or
psi_cgroup_alloc() fails.
Signed-off-by: JP Kobryn <inwardvessel@gmail.com>
Fixes: a97915559f ("cgroup: change rstat function signatures from cgroup-based to css-based")
Signed-off-by: Tejun Heo <tj@kernel.org>
* Single fix for broken usage of 'multi-MIDR' infrastructure in PI
code, adding an open-coded erratum check for Cavium ThunderX
* Bugfixes from a planned posted interrupt rework
* Do not use kvm_rip_read() unconditionally to cater for guests
with inaccessible register state.
In css_rstat_init() allocations are done for the cgroup's pointers
rstat_cpu and rstat_base_cpu. Make sure the allocation checks are
consistent with what they are allocating.
Signed-off-by: JP Kobryn <inwardvessel@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Android has mounted the v1 cpuset controller using filesystem type
"cpuset" (not "cgroup") since 2015 [1], and depends on the resulting
behavior where the controller name is not added as a prefix for cgroupfs
files. [2]
Later, a problem was discovered where cpu hotplug onlining did not
affect the cpuset/cpus files, which Android carried an out-of-tree patch
to address for a while. An attempt was made to upstream this patch, but
the recommendation was to use the "cpuset_v2_mode" mount option
instead. [3]
An effort was made to do so, but this fails with "cgroup: Unknown
parameter 'cpuset_v2_mode'" because commit e1cba4b85d ("cgroup: Add
mount flag to enable cpuset to use v2 behavior in v1 cgroup") did not
update the special cased cpuset_mount(), and only the cgroup (v1)
filesystem type was updated.
Add parameter parsing to the cpuset filesystem type so that
cpuset_v2_mode works like the cgroup filesystem type:
$ mkdir /dev/cpuset
$ mount -t cpuset -ocpuset_v2_mode none /dev/cpuset
$ mount|grep cpuset
none on /dev/cpuset type cgroup (rw,relatime,cpuset,noprefix,cpuset_v2_mode,release_agent=/sbin/cpuset_release_agent)
[1] b769c8d24f
[2] https://cs.android.com/android/platform/superproject/main/+/main:system/core/libprocessgroup/setup/cgroup_map_write.cpp;drc=2dac5d89a0f024a2d0cc46a80ba4ee13472f1681;l=192
[3] https://lore.kernel.org/lkml/f795f8be-a184-408a-0b5a-553d26061385@redhat.com/T/
Fixes: e1cba4b85d ("cgroup: Add mount flag to enable cpuset to use v2 behavior in v1 cgroup")
Signed-off-by: T.J. Mercier <tjmercier@google.com>
Acked-by: Waiman Long <longman@redhat.com>
Reviewed-by: Kamalesh Babulal <kamalesh.babulal@oracle.com>
Acked-by: Michal Koutný <mkoutny@suse.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
When adding folio_memcg function call in the zram module for
Android16-6.12, the following error occurs during compilation:
ERROR: modpost: "cgroup_mutex" [../soc-repo/zram.ko] undefined!
This error is caused by the indirect call to lockdep_is_held(&cgroup_mutex)
within folio_memcg. The export setting for cgroup_mutex is controlled by
the CONFIG_PROVE_RCU macro. If CONFIG_LOCKDEP is enabled while
CONFIG_PROVE_RCU is not, this compilation error will occur.
To resolve this issue, add a parallel macro CONFIG_LOCKDEP control to
ensure cgroup_mutex is properly exported when needed.
Signed-off-by: gao xu <gaoxu2@honor.com>
Acked-by: Michal Koutný <mkoutny@suse.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
- A number of cpuset remote partition related fixes and cleanups along with
selftest updates.
- A change from this merge window made cgroup_rstat_updated_list() called
outside cgroup_rstat_lock leading to list corruptions. Fix it by
relocating the call inside the lock.
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Merge tag 'cgroup-for-6.15-rc1-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup
Pull cgroup fixes from Tejun Heo:
- A number of cpuset remote partition related fixes and cleanups along
with selftest updates.
- A change from this merge window made cgroup_rstat_updated_list()
called outside cgroup_rstat_lock leading to list corruptions. Fix it
by relocating the call inside the lock.
* tag 'cgroup-for-6.15-rc1-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
cgroup/cpuset: Fix race between newly created partition and dying one
cgroup: rstat: call cgroup_rstat_updated_list with cgroup_rstat_lock
selftest/cgroup: Add a remote partition transition test to test_cpuset_prs.sh
selftest/cgroup: Clean up and restructure test_cpuset_prs.sh
selftest/cgroup: Update test_cpuset_prs.sh to use | as effective CPUs and state separator
cgroup/cpuset: Remove unneeded goto in sched_partition_write() and rename it
cgroup/cpuset: Code cleanup and comment update
cgroup/cpuset: Don't allow creation of local partition over a remote one
cgroup/cpuset: Remove remote_partition_check() & make update_cpumasks_hier() handle remote partition
cgroup/cpuset: Fix error handling in remote_partition_disable()
cgroup/cpuset: Fix incorrect isolated_cpus update in update_parent_effective_cpumask()
Add WARN_ON_ONCE() statements whenever new exclusive CPUs are being
added to a partition root to catch inconsistency in the way exclusive
CPUs are being handled in the cpuset code.
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Move the partition disablement comment from cpuset_css_offline()
to cpuset_css_killed() and reword it to remove the remnant of
sched.partition.
Suggested-by: Michal Koutný <mkoutny@suse.com>
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
The current cpuset code uses both cpu_active_mask and cpu_online_mask
and it can be confusing which one should be used if we need to update
the code.
The top_cpuset is always synchronized to cpu_active_mask and we should
avoid using cpu_online_mask as much as possible. An active CPU is always
an online CPU, but not vice versa. cpu_active_mask and cpu_online_mask
can differ during hotplug operations.
A CPU is marked active at the last stage of CPU bringup (CPUHP_AP_ACTIVE).
It is also the stage where cpuset hotplug code will be called to update
the sched domains so that the scheduler can move a normal task to a
newly active CPU or remove tasks away from a newly inactivated CPU. The
online bit is set much earlier in the CPU bringup process and cleared
much later in CPU teardown.
If cpu_online_mask is used while a hotunplug operation is happening in
parallel, we may leave an offline CPU in cpu_allowed or have a higher
chance of leaving an offline CPU in some other masks. Avoid this
problem by always using cpu_active_mask in the cpuset code and leave
a comment as to why the use of cpu_online_mask is discouraged.
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
This large commit contains the initial support for TDX in KVM. All x86
parts enable the host-side hypercalls that KVM uses to talk to the TDX
module, a software component that runs in a special CPU mode called SEAM
(Secure Arbitration Mode).
The series is in turn split into multiple sub-series, each with a separate
merge commit:
- Initialization: basic setup for using the TDX module from KVM, plus
ioctls to create TDX VMs and vCPUs.
- MMU: in TDX, private and shared halves of the address space are mapped by
different EPT roots, and the private half is managed by the TDX module.
Using the support that was added to the generic MMU code in 6.14,
add support for TDX's secure page tables to the Intel side of KVM.
Generic KVM code takes care of maintaining a mirror of the secure page
tables so that they can be queried efficiently, and ensuring that changes
are applied to both the mirror and the secure EPT.
- vCPU enter/exit: implement the callbacks that handle the entry of a TDX
vCPU (via the SEAMCALL TDH.VP.ENTER) and the corresponding save/restore
of host state.
- Userspace exits: introduce support for guest TDVMCALLs that KVM forwards to
userspace. These correspond to the usual KVM_EXIT_* "heavyweight vmexits"
but are triggered through a different mechanism, similar to VMGEXIT for
SEV-ES and SEV-SNP.
- Interrupt handling: support for virtual interrupt injection as well as
handling VM-Exits that are caused by vectored events. Exclusive to
TDX are machine-check SMIs, which the kernel already knows how to
handle through the kernel machine check handler (commit 7911f145de,
"x86/mce: Implement recovery for errors in TDX/SEAM non-root mode")
- Loose ends: handling of the remaining exits from the TDX module, including
EPT violation/misconfig and several TDVMCALL leaves that are handled in
the kernel (CPUID, HLT, RDMSR/WRMSR, GetTdVmCallInfo); plus returning
an error or ignoring operations that are not supported by TDX guests
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
timer_delete[_sync]() replaces del_timer[_sync](). Convert the whole tree
over and remove the historical wrapper inlines.
Conversion was done with coccinelle plus manual fixups where necessary.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This non-functional change serves as preparation for moving to
subsystem-based rstat trees. To simplify future commits, change the
signatures of existing cgroup-based rstat functions to become css-based and
rename them to reflect that.
Though the signatures have changed, the implementations have not. Within
these functions use the css->cgroup pointer to obtain the associated cgroup
and allow code to function the same just as it did before this patch. At
applicable call sites, pass the subsystem-specific css pointer as an
argument or pass a pointer to cgroup::self if not in subsystem context.
Note that cgroup_rstat_updated_list() and cgroup_rstat_push_children()
are not altered yet since there would be a larger amount of css to
cgroup conversions which may overcomplicate the code at this
intermediate phase.
Signed-off-by: JP Kobryn <inwardvessel@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
The cgroup struct has a css field called "self". The main difference
between this css and the others found in the cgroup::subsys array is that
cgroup::self has a NULL subsystem pointer. There are several places where
checks are performed to determine whether the css in question is
cgroup::self or not. Instead of accessing css->ss directly, introduce a
helper function that shows the intent and use where applicable.
Signed-off-by: JP Kobryn <inwardvessel@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
This non-functional change serves as preparation for moving to
subsystem-based rstat trees. The base stats are not an actual subsystem,
but in future commits they will have exclusive rstat trees just as other
subsystems will.
Moving the base stat objects into a new struct allows the cgroup_rstat_cpu
struct to become more compact since it now only contains the minimum amount
of pointers needed for rstat participation. Subsystems will (in future
commits) make use of the compact cgroup_rstat_cpu struct while avoiding the
memory overhead of the base stat objects which they will not use.
An instance of the new struct cgroup_rstat_base_cpu was placed on the
cgroup struct so it can retain ownership of these base stats common to all
cgroups. A helper function was added for looking up the cpu-specific base
stats of a given cgroup. Finally, initialization and variable names were
adjusted where applicable.
Signed-off-by: JP Kobryn <inwardvessel@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
There is a possible race between removing a cgroup diectory that is
a partition root and the creation of a new partition. The partition
to be removed can be dying but still online, it doesn't not currently
participate in checking for exclusive CPUs conflict, but the exclusive
CPUs are still there in subpartitions_cpus and isolated_cpus. These
two cpumasks are global states that affect the operation of cpuset
partitions. The exclusive CPUs in dying cpusets will only be removed
when cpuset_css_offline() function is called after an RCU delay.
As a result, it is possible that a new partition can be created with
exclusive CPUs that overlap with those of a dying one. When that dying
partition is finally offlined, it removes those overlapping exclusive
CPUs from subpartitions_cpus and maybe isolated_cpus resulting in an
incorrect CPU configuration.
This bug was found when a warning was triggered in
remote_partition_disable() during testing because the subpartitions_cpus
mask was empty.
One possible way to fix this is to iterate the dying cpusets as well and
avoid using the exclusive CPUs in those dying cpusets. However, this
can still cause random partition creation failures or other anomalies
due to racing. A better way to fix this race is to reset the partition
state at the moment when a cpuset is being killed.
Introduce a new css_killed() CSS function pointer and call it, if
defined, before setting CSS_DYING flag in kill_css(). Also update the
css_is_dying() helper to use the CSS_DYING flag introduced by commit
33c35aa481 ("cgroup: Prevent kill_css() from being called more than
once") for proper synchronization.
Add a new cpuset_css_killed() function to reset the partition state of
a valid partition root if it is being killed.
Fixes: ee8dde0cd2 ("cpuset: Add new v2 cpuset.sched.partition flag")
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Here is the big set of driver core updates for 6.15-rc1. Lots of stuff
happened this development cycle, including:
- kernfs scaling changes to make it even faster thanks to rcu
- bin_attribute constify work in many subsystems
- faux bus minor tweaks for the rust bindings
- rust binding updates for driver core, pci, and platform busses,
making more functionaliy available to rust drivers. These are all
due to people actually trying to use the bindings that were in 6.14.
- make Rafael and Danilo full co-maintainers of the driver core
codebase
- other minor fixes and updates.
This has been in linux-next for a while now, with the only reported
issue being some merge conflicts with the rust tree. Depending on which
tree you pull first, you will have conflicts in one of them. The merge
resolution has been in linux-next as an example of what to do, or can be
found here:
https://lore.kernel.org/r/CANiq72n3Xe8JcnEjirDhCwQgvWoE65dddWecXnfdnbrmuah-RQ@mail.gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Merge tag 'driver-core-6.15-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core
Pull driver core updatesk from Greg KH:
"Here is the big set of driver core updates for 6.15-rc1. Lots of stuff
happened this development cycle, including:
- kernfs scaling changes to make it even faster thanks to rcu
- bin_attribute constify work in many subsystems
- faux bus minor tweaks for the rust bindings
- rust binding updates for driver core, pci, and platform busses,
making more functionaliy available to rust drivers. These are all
due to people actually trying to use the bindings that were in
6.14.
- make Rafael and Danilo full co-maintainers of the driver core
codebase
- other minor fixes and updates"
* tag 'driver-core-6.15-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core: (52 commits)
rust: platform: require Send for Driver trait implementers
rust: pci: require Send for Driver trait implementers
rust: platform: impl Send + Sync for platform::Device
rust: pci: impl Send + Sync for pci::Device
rust: platform: fix unrestricted &mut platform::Device
rust: pci: fix unrestricted &mut pci::Device
rust: device: implement device context marker
rust: pci: use to_result() in enable_device_mem()
MAINTAINERS: driver core: mark Rafael and Danilo as co-maintainers
rust/kernel/faux: mark Registration methods inline
driver core: faux: only create the device if probe() succeeds
rust/faux: Add missing parent argument to Registration::new()
rust/faux: Drop #[repr(transparent)] from faux::Registration
rust: io: fix devres test with new io accessor functions
rust: io: rename `io::Io` accessors
kernfs: Move dput() outside of the RCU section.
efi: rci2: mark bin_attribute as __ro_after_init
rapidio: constify 'struct bin_attribute'
firmware: qemu_fw_cfg: constify 'struct bin_attribute'
powerpc/perf/hv-24x7: Constify 'struct bin_attribute'
...
The goto statement in sched_partition_write() is not needed. Remove
it and rename sched_partition_write()/sched_partition_show() to
cpuset_partition_write()/cpuset_partition_show().
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Rename partition_xcpus_newstate() to isolated_cpus_update(),
update_partition_exclusive() to update_partition_exclusive_flag() and
the new_xcpus_state variable to isolcpus_updated to make their meanings
more explicit. Also add some comments to further clarify the code.
No functional change is expected.
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Currently, we don't allow the creation of a remote partition underneath
another local or remote partition. However, it is currently possible to
create a new local partition with an existing remote partition underneath
it if top_cpuset is the parent. However, the current cpuset code does
not set the effective exclusive CPUs correctly to account for those
that are taken by the remote partition.
Changing the code to properly account for those remote partition CPUs
under all possible circumstances can be complex. It is much easier to
not allow such a configuration which is not that useful. So forbid
that by making sure that exclusive_cpus mask doesn't overlap with
subpartitions_cpus and invalidate the partition if that happens.
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Currently, changes in exclusive CPUs are being handled in
remote_partition_check() by disabling conflicting remote partitions.
However, that may lead to results unexpected by the users. Fix
this problem by removing remote_partition_check() and making
update_cpumasks_hier() handle changes in descendant remote partitions
properly.
The compute_effective_exclusive_cpumask() function is enhanced to check
the exclusive_cpus and effective_xcpus from siblings and excluded them
in its effective exclusive CPUs computation and return a value to show if
there is any sibling conflicts. This is somewhat like the cpu_exclusive
flag check in validate_change(). This is the initial step to enable us
to retire the use of cpu_exclusive flag in cgroup v2 in the future.
One of the tests in the TEST_MATRIX of the test_cpuset_prs.sh
script has to be updated due to changes in the way a child remote
partition root is being handled (updated instead of invalidation)
in update_cpumasks_hier().
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
When remote_partition_disable() is called to disable a remote partition,
it always sets the partition to an invalid partition state. It should
only do so if an error code (prs_err) has been set. Correct that and
add proper error code in places where remote_partition_disable() is
called due to error.
Fixes: 181c8e091a ("cgroup/cpuset: Introduce remote partition")
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Before commit f0af1bfc27 ("cgroup/cpuset: Relax constraints to
partition & cpus changes"), a cpuset partition cannot be enabled if not
all the requested CPUs can be granted from the parent cpuset. After
that commit, a cpuset partition can be created even if the requested
exclusive CPUs contain CPUs not allowed its parent. The delmask
containing exclusive CPUs to be removed from its parent wasn't
adjusted accordingly.
That is not a problem until the introduction of a new isolated_cpus
mask in commit 11e5f407b6 ("cgroup/cpuset: Keep track of CPUs in
isolated partitions") as the CPUs in the delmask may be added directly
into isolated_cpus.
As a result, isolated_cpus may incorrectly contain CPUs that are not
isolated leading to incorrect data reporting. Fix this by adjusting
the delmask to reflect the actual exclusive CPUs for the creation of
the partition.
Fixes: 11e5f407b6 ("cgroup/cpuset: Keep track of CPUs in isolated partitions")
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
[ Merge note, these two commits are identical:
- f3fa0e40df ("sched/clock: Don't define sched_clock_irqtime as static key")
- b9f2b29b94 ("sched: Don't define sched_clock_irqtime as static key")
The first one is a cherry-picked version of the second, and the first one
is already upstream. ]
Core & fair scheduler changes:
- Cancel the slice protection of the idle entity (Zihan Zhou)
- Reduce the default slice to avoid tasks getting an extra tick
(Zihan Zhou)
- Force propagating min_slice of cfs_rq when {en,de}queue tasks
(Tianchen Ding)
- Refactor can_migrate_task() to elimate looping (I Hsin Cheng)
- Add unlikey branch hints to several system calls (Colin Ian King)
- Optimize current_clr_polling() on certain architectures (Yujun Dong)
Deadline scheduler: (Juri Lelli)
- Remove redundant dl_clear_root_domain call
- Move dl_rebuild_rd_accounting to cpuset.h
Uclamp:
- Use the uclamp_is_used() helper instead of open-coding it (Xuewen Yan)
- Optimize sched_uclamp_used static key enabling (Xuewen Yan)
Scheduler topology support: (Juri Lelli)
- Ignore special tasks when rebuilding domains
- Add wrappers for sched_domains_mutex
- Generalize unique visiting of root domains
- Rebuild root domain accounting after every update
- Remove partition_and_rebuild_sched_domains
- Stop exposing partition_sched_domains_locked
RSEQ: (Michael Jeanson)
- Update kernel fields in lockstep with CONFIG_DEBUG_RSEQ=y
- Fix segfault on registration when rseq_cs is non-zero
- selftests: Add rseq syscall errors test
- selftests: Ensure the rseq ABI TLS is actually 1024 bytes
Membarriers:
- Fix redundant load of membarrier_state (Nysal Jan K.A.)
Scheduler debugging:
- Introduce and use preempt_model_str() (Sebastian Andrzej Siewior)
- Make CONFIG_SCHED_DEBUG unconditional (Ingo Molnar)
Fixes and cleanups:
- Always save/restore x86 TSC sched_clock() on suspend/resume
(Guilherme G. Piccoli)
- Misc fixes and cleanups (Thorsten Blum, Juri Lelli,
Sebastian Andrzej Siewior)
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'sched-core-2025-03-22' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler updates from Ingo Molnar:
"Core & fair scheduler changes:
- Cancel the slice protection of the idle entity (Zihan Zhou)
- Reduce the default slice to avoid tasks getting an extra tick
(Zihan Zhou)
- Force propagating min_slice of cfs_rq when {en,de}queue tasks
(Tianchen Ding)
- Refactor can_migrate_task() to elimate looping (I Hsin Cheng)
- Add unlikey branch hints to several system calls (Colin Ian King)
- Optimize current_clr_polling() on certain architectures (Yujun
Dong)
Deadline scheduler: (Juri Lelli)
- Remove redundant dl_clear_root_domain call
- Move dl_rebuild_rd_accounting to cpuset.h
Uclamp:
- Use the uclamp_is_used() helper instead of open-coding it (Xuewen
Yan)
- Optimize sched_uclamp_used static key enabling (Xuewen Yan)
Scheduler topology support: (Juri Lelli)
- Ignore special tasks when rebuilding domains
- Add wrappers for sched_domains_mutex
- Generalize unique visiting of root domains
- Rebuild root domain accounting after every update
- Remove partition_and_rebuild_sched_domains
- Stop exposing partition_sched_domains_locked
RSEQ: (Michael Jeanson)
- Update kernel fields in lockstep with CONFIG_DEBUG_RSEQ=y
- Fix segfault on registration when rseq_cs is non-zero
- selftests: Add rseq syscall errors test
- selftests: Ensure the rseq ABI TLS is actually 1024 bytes
Membarriers:
- Fix redundant load of membarrier_state (Nysal Jan K.A.)
Scheduler debugging:
- Introduce and use preempt_model_str() (Sebastian Andrzej Siewior)
- Make CONFIG_SCHED_DEBUG unconditional (Ingo Molnar)
Fixes and cleanups:
- Always save/restore x86 TSC sched_clock() on suspend/resume
(Guilherme G. Piccoli)
- Misc fixes and cleanups (Thorsten Blum, Juri Lelli, Sebastian
Andrzej Siewior)"
* tag 'sched-core-2025-03-22' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (40 commits)
cpuidle, sched: Use smp_mb__after_atomic() in current_clr_polling()
sched/debug: Remove CONFIG_SCHED_DEBUG
sched/debug: Remove CONFIG_SCHED_DEBUG from self-test config files
sched/debug, Documentation: Remove (most) CONFIG_SCHED_DEBUG references from documentation
sched/debug: Make CONFIG_SCHED_DEBUG functionality unconditional
sched/debug: Make 'const_debug' tunables unconditional __read_mostly
sched/debug: Change SCHED_WARN_ON() to WARN_ON_ONCE()
rseq/selftests: Fix namespace collision with rseq UAPI header
include/{topology,cpuset}: Move dl_rebuild_rd_accounting to cpuset.h
sched/topology: Stop exposing partition_sched_domains_locked
cgroup/cpuset: Remove partition_and_rebuild_sched_domains
sched/topology: Remove redundant dl_clear_root_domain call
sched/deadline: Rebuild root domain accounting after every update
sched/deadline: Generalize unique visiting of root domains
sched/topology: Wrappers for sched_domains_mutex
sched/deadline: Ignore special tasks when rebuilding domains
tracing: Use preempt_model_str()
xtensa: Rely on generic printing of preemption model
x86: Rely on generic printing of preemption model
s390: Rely on generic printing of preemption model
...
- Add deprecation info messages to cgroup1-only features.
- rstat updates including a bug fix and breaking up a critical section to
reduce interrupt latency impact.
- Other misc and doc updates.
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Merge tag 'cgroup-for-6.15' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup
Pull cgroup updates from Tejun Heo:
- Add deprecation info messages to cgroup1-only features
- rstat updates including a bug fix and breaking up a critical section
to reduce interrupt latency impact
- Other misc and doc updates
* tag 'cgroup-for-6.15' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
cgroup: rstat: Cleanup flushing functions and locking
cgroup/rstat: avoid disabling irqs for O(num_cpu)
mm: Fix a build breakage in memcontrol-v1.c
blk-cgroup: Simplify policy files registration
cgroup: Update file naming comment
cgroup: Add deprecation message to legacy freezer controller
mm: Add transformation message for per-memcg swappiness
RFC cgroup/cpuset-v1: Add deprecation messages to sched_relax_domain_level
cgroup/cpuset-v1: Add deprecation messages to memory_migrate
cgroup/cpuset-v1: Add deprecation messages to mem_exclusive and mem_hardwall
cgroup: Print message when /proc/cgroups is read on v2-only system
cgroup/blkio: Add deprecation messages to reset_stats
cgroup/cpuset-v1: Add deprecation messages to memory_spread_page and memory_spread_slab
cgroup/cpuset-v1: Add deprecation messages to sched_load_balance and memory_pressure_enabled
cgroup, docs: Be explicit about independence of RT_GROUP_SCHED and non-cpu controllers
cgroup/rstat: Fix forceidle time in cpu.stat
cgroup/misc: Remove unused misc_cg_res_total_usage
cgroup/cpuset: Move procfs cpuset attribute under cgroup-v1.c
cgroup: update comment about dropping cgroup kn refs
Now that the rstat lock is being re-acquired on every CPU iteration in
cgroup_rstat_flush_locked(), having the initially acquire the lock is
unnecessary and unclear.
Inline cgroup_rstat_flush_locked() into cgroup_rstat_flush() and move
the lock/unlock calls to the beginning and ending of the loop body to
make the critical section obvious.
cgroup_rstat_flush_hold/release() do not make much sense with the lock
being dropped and reacquired internally. Since it has no external
callers, remove it and explicitly acquire the lock in
cgroup_base_stat_cputime_show() instead.
This leaves the code with a single flushing function,
cgroup_rstat_flush().
Signed-off-by: Yosry Ahmed <yosry.ahmed@linux.dev>
Signed-off-by: Tejun Heo <tj@kernel.org>
cgroup_rstat_flush_locked() grabs the irq safe cgroup_rstat_lock while
iterating all possible cpus. It only drops the lock if there is
scheduler or spin lock contention. If neither, then interrupts can be
disabled for a long time. On large machines this can disable interrupts
for a long enough time to drop network packets. On 400+ CPU machines
I've seen interrupt disabled for over 40 msec.
Prevent rstat from disabling interrupts while processing all possible
cpus. Instead drop and reacquire cgroup_rstat_lock for each cpu. This
approach was previously discussed in
https://lore.kernel.org/lkml/ZBz%2FV5a7%2F6PZeM7S@slm.duckdns.org/,
though this was in the context of an non-irq rstat spin lock.
Benchmark this change with:
1) a single stat_reader process with 400 threads, each reading a test
memcg's memory.stat repeatedly for 10 seconds.
2) 400 memory hog processes running in the test memcg and repeatedly
charging memory until oom killed. Then they repeat charging and oom
killing.
v6.14-rc6 with CONFIG_IRQSOFF_TRACER with stat_reader and hogs, finds
interrupts are disabled by rstat for 45341 usec:
# => started at: _raw_spin_lock_irq
# => ended at: cgroup_rstat_flush
#
#
# _------=> CPU#
# / _-----=> irqs-off/BH-disabled
# | / _----=> need-resched
# || / _---=> hardirq/softirq
# ||| / _--=> preempt-depth
# |||| / _-=> migrate-disable
# ||||| / delay
# cmd pid |||||| time | caller
# \ / |||||| \ | /
stat_rea-96532 52d.... 0us*: _raw_spin_lock_irq
stat_rea-96532 52d.... 45342us : cgroup_rstat_flush
stat_rea-96532 52d.... 45342us : tracer_hardirqs_on <-cgroup_rstat_flush
stat_rea-96532 52d.... 45343us : <stack trace>
=> memcg1_stat_format
=> memory_stat_format
=> memory_stat_show
=> seq_read_iter
=> vfs_read
=> ksys_read
=> do_syscall_64
=> entry_SYSCALL_64_after_hwframe
With this patch the CONFIG_IRQSOFF_TRACER doesn't find rstat to be the
longest holder. The longest irqs-off holder has irqs disabled for
4142 usec, a huge reduction from previous 45341 usec rstat finding.
Running stat_reader memory.stat reader for 10 seconds:
- without memory hogs: 9.84M accesses => 12.7M accesses
- with memory hogs: 9.46M accesses => 11.1M accesses
The throughput of memory.stat access improves.
The mode of memory.stat access latency after grouping by of 2 buckets:
- without memory hogs: 64 usec => 16 usec
- with memory hogs: 64 usec => 8 usec
The memory.stat latency improves.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Greg Thelen <gthelen@google.com>
Tested-by: Greg Thelen <gthelen@google.com>
Acked-by: Michal Koutný <mkoutny@suse.com>
Reviewed-by: Yosry Ahmed <yosry.ahmed@linux.dev>
Signed-off-by: Tejun Heo <tj@kernel.org>
partition_and_rebuild_sched_domains() and partition_sched_domains() are
now equivalent.
Remove the former as a nice clean up.
Suggested-by: Waiman Long <llong@redhat.com>
Signed-off-by: Juri Lelli <juri.lelli@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Waiman Long <llong@redhat.com>
Reviewed-by: Shrikanth Hegde <sshegde@linux.ibm.com>
Reviewed-by: Valentin Schneider <vschneid@redhat.com>
Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Tested-by: Waiman Long <longman@redhat.com>
Tested-by: Jon Hunter <jonathanh@nvidia.com>
Tested-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Link: https://lore.kernel.org/r/Z9MR4ryNDJZDzsSG@jlelli-thinkpadt14gen4.remote.csb
Rebuilding of root domains accounting information (total_bw) is
currently broken on some cases, e.g. suspend/resume on aarch64. Problem
is that the way we keep track of domain changes and try to add bandwidth
back is convoluted and fragile.
Fix it by simplify things by making sure bandwidth accounting is cleared
and completely restored after root domains changes (after root domains
are again stable).
To be sure we always call dl_rebuild_rd_accounting while holding
cpuset_mutex we also add cpuset_reset_sched_domains() wrapper.
Fixes: 53916d5fd3 ("sched/deadline: Check bandwidth overflow earlier for hotplug")
Reported-by: Jon Hunter <jonathanh@nvidia.com>
Co-developed-by: Waiman Long <llong@redhat.com>
Signed-off-by: Waiman Long <llong@redhat.com>
Signed-off-by: Juri Lelli <juri.lelli@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Tested-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Link: https://lore.kernel.org/r/Z9MRfeJKJUOyUSto@jlelli-thinkpadt14gen4.remote.csb
Create wrappers for sched_domains_mutex so that it can transparently be
used on both CONFIG_SMP and !CONFIG_SMP, as some function will need to
do.
Fixes: 53916d5fd3 ("sched/deadline: Check bandwidth overflow earlier for hotplug")
Reported-by: Jon Hunter <jonathanh@nvidia.com>
Signed-off-by: Juri Lelli <juri.lelli@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Valentin Schneider <vschneid@redhat.com>
Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Tested-by: Waiman Long <longman@redhat.com>
Tested-by: Jon Hunter <jonathanh@nvidia.com>
Tested-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Link: https://lore.kernel.org/r/Z9MP5Oq9RB8jBs3y@jlelli-thinkpadt14gen4.remote.csb
TDX host key IDs (HKID) are limit resources in a machine, and the misc
cgroup lets the machine owner track their usage and limits the possibility
of abusing them outside the owner's control.
The cgroup v2 miscellaneous subsystem was introduced to control the
resource of AMD SEV & SEV-ES ASIDs. Likewise introduce HKIDs as a misc
resource.
Signed-off-by: Zhiming Hu <zhiming.hu@intel.com>
Signed-off-by: Isaku Yamahata <isaku.yamahata@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Use one set of files when there is no difference between default and
legacy files, similar to regular subsys files registration. No
functional change.
Signed-off-by: Michal Koutný <mkoutny@suse.com>
Acked-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Tejun Heo <tj@kernel.org>
As explained in the commit 76f969e894 ("cgroup: cgroup v2 freezer"),
the original freezer is imperfect, some users may unwittingly rely on it
when there exists the alternative of v2. Print a message when it happens
and explain that in the docs.
Signed-off-by: Michal Koutný <mkoutny@suse.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
