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Commit fe8cd2736e75 ("cgroup/cpuset: Delay setting of CS_CPU_EXCLUSIVE
until valid partition") introduced a new check to disallow the setting
of a new cpuset.cpus.exclusive value that is a superset of a sibling's
cpuset.cpus value so that there will at least be one CPU left in the
sibling in case the cpuset becomes a valid partition root. This new
check does have the side effect of failing a cpuset.cpus change that
make it a subset of a sibling's cpuset.cpus.exclusive value.
With v2, users are supposed to be allowed to set whatever value they
want in cpuset.cpus without failure. To maintain this rule, the check
is now restricted to only when cpuset.cpus.exclusive is being changed
not when cpuset.cpus is changed.
The cgroup-v2.rst doc file is also updated to reflect this change.
Signed-off-by: Waiman Long <longman@redhat.com>
Reviewed-by: Chen Ridong <chenridong@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
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Since commit f62a5d39368e ("cgroup/cpuset: Remove remote_partition_check()
& make update_cpumasks_hier() handle remote partition"), the
compute_effective_exclusive_cpumask() helper was extended to
strip exclusive CPUs from siblings when computing effective_xcpus
(cpuset.cpus.exclusive.effective). This helper was later renamed to
compute_excpus() in commit 86bbbd1f33ab ("cpuset: Refactor exclusive
CPU mask computation logic").
This helper is supposed to be used consistently to compute
effective_xcpus. However, there is an exception within the callback
critical section in update_cpumasks_hier() when exclusive_cpus of a
valid partition root is empty. This can cause effective_xcpus value to
differ depending on where exactly it is last computed. Fix this by using
compute_excpus() in this case to give a consistent result.
Signed-off-by: Waiman Long <longman@redhat.com>
Reviewed-by: Chen Ridong <chenridong@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
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If exclusive_cpus is set, effective_xcpus must be a subset of
exclusive_cpus. Currently, rm_siblings_excl_cpus() checks both
exclusive_cpus and effective_xcpus consecutively. It is simpler
to check only exclusive_cpus if non-empty or just effective_xcpus
otherwise.
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>
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Paravirt clock related functions are available in multiple archs.
In order to share the common parts, move the common static keys
to kernel/sched/ and remove them from the arch specific files.
Make a common paravirt_steal_clock() implementation available in
kernel/sched/cputime.c, guarding it with a new config option
CONFIG_HAVE_PV_STEAL_CLOCK_GEN, which can be selected by an arch
in case it wants to use that common variant.
Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260105110520.21356-7-jgross@suse.com
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All architectures supporting CONFIG_PARAVIRT share the same contents
of asm/paravirt_api_clock.h:
#include <asm/paravirt.h>
So remove all incarnations of asm/paravirt_api_clock.h and remove the
only place where it is included, as there asm/paravirt.h is included
anyway.
Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Shrikanth Hegde <sshegde@linux.ibm.com> # powerpc, scheduler bits
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260105110520.21356-6-jgross@suse.com
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler fix from Ingo Molnar:
"Fix a crash in sched_mm_cid_after_execve()"
* tag 'sched-urgent-2026-01-11' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
sched/mm_cid: Prevent NULL mm dereference in sched_mm_cid_after_execve()
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull perf event fix from Ingo Molnar:
"Fix perf swevent hrtimer deinit regression"
* tag 'perf-urgent-2026-01-11' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
perf: Ensure swevent hrtimer is properly destroyed
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In a vain attempt to consolidate the email zoo switch everything to the
kernel.org account.
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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* rcu-misc.20260111a:
rcu: Reduce synchronize_rcu() latency by reporting GP kthread's CPU QS early
srcu: Use suitable gfp_flags for the init_srcu_struct_nodes()
rcu: Fix rcu_read_unlock() deadloop due to softirq
rcutorture: Correctly compute probability to invoke ->exp_current()
rcu: Make expedited RCU CPU stall warnings detect stall-end races
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The RCU grace period mechanism uses a two-phase FQS (Force Quiescent
State) design where the first FQS saves dyntick-idle snapshots and
the second FQS compares them. This results in long and unnecessary latency
for synchronize_rcu() on idle systems (two FQS waits of ~3ms each with
1000HZ) whenever one FQS wait sufficed.
Some investigations showed that the GP kthread's CPU is the holdout CPU
a lot of times after the first FQS as - it cannot be detected as "idle"
because it's actively running the FQS scan in the GP kthread.
Therefore, at the end of rcu_gp_init(), immediately report a quiescent
state for the GP kthread's CPU using rcu_qs() + rcu_report_qs_rdp(). The
GP kthread cannot be in an RCU read-side critical section while running
GP initialization, so this is safe and results in significant latency
improvements.
The following tests were performed:
(1) synchronize_rcu() benchmarking
100 synchronize_rcu() calls with 32 CPUs, 10 runs each (default fqs
jiffies settings):
Baseline (without fix):
| Run | Mean | Min | Max |
|-----|-----------|----------|-----------|
| 1 | 10.088 ms | 9.989 ms | 18.848 ms |
| 2 | 10.064 ms | 9.982 ms | 16.470 ms |
| 3 | 10.051 ms | 9.988 ms | 15.113 ms |
| 4 | 10.125 ms | 9.929 ms | 22.411 ms |
| 5 | 8.695 ms | 5.996 ms | 15.471 ms |
| 6 | 10.157 ms | 9.977 ms | 25.723 ms |
| 7 | 10.102 ms | 9.990 ms | 20.224 ms |
| 8 | 8.050 ms | 5.985 ms | 10.007 ms |
| 9 | 10.059 ms | 9.978 ms | 15.934 ms |
| 10 | 10.077 ms | 9.984 ms | 17.703 ms |
With fix:
| Run | Mean | Min | Max |
|-----|----------|----------|-----------|
| 1 | 6.027 ms | 5.915 ms | 8.589 ms |
| 2 | 6.032 ms | 5.984 ms | 9.241 ms |
| 3 | 6.010 ms | 5.986 ms | 7.004 ms |
| 4 | 6.076 ms | 5.993 ms | 10.001 ms |
| 5 | 6.084 ms | 5.893 ms | 10.250 ms |
| 6 | 6.034 ms | 5.908 ms | 9.456 ms |
| 7 | 6.051 ms | 5.993 ms | 10.000 ms |
| 8 | 6.057 ms | 5.941 ms | 10.001 ms |
| 9 | 6.016 ms | 5.927 ms | 7.540 ms |
| 10 | 6.036 ms | 5.993 ms | 9.579 ms |
Summary:
- Mean latency: 9.75 ms -> 6.04 ms (38% improvement)
- Max latency: 25.72 ms -> 10.25 ms (60% improvement)
(2) Bridge setup/teardown latency (Uladzislau Rezki)
x86_64 with 64 CPUs, 100 iterations of bridge add/configure/delete:
real time
1 - default: 24.221s
2 - this patch: 20.754s (14% faster)
3 - this patch + wake_from_gp: 15.895s (34% faster)
4 - wake_from_gp only: 18.947s (22% faster)
Per-synchronize_rcu() latency (in usec):
1 2 3 4
median: 37249.5 31540.5 15765 22480
min: 7881 7918 9803 7857
max: 63651 55639 31861 32040
This patch combined with rcu_normal_wake_from_gp reduces bridge
setup/teardown time from 24 seconds to 16 seconds.
(3) CPU overhead verification (Uladzislau Rezki)
System CPU time across 5 runs showed no measurable increase:
default: 1.698s - 1.937s
this patch: 1.667s - 1.930s
Conclusion: variations are within noise, no CPU overhead regression.
(4) rcutorture
Tested TREE and SRCU configurations - no regressions.
Reviewed-by: "Paul E. McKenney" <paulmck@kernel.org>
Tested-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Tested-by: Paul E. McKenney <paulmck@kernel.org>
Tested-by: Samir M <samir@linux.ibm.com>
Signed-off-by: Joel Fernandes <joelagnelf@nvidia.com>
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
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Add dump to get-perf-domains, so that a user can fetch either information
about a specific performance domain with do or information about all
performance domains with dump. Share the reply format of do and dump using
perf-domain-attrs, so remove perf-domains. The YNL spec, autogenerated
files, and the do implementation are updated, and the dump implementation
is added.
Suggested-by: Donald Hunter <donald.hunter@gmail.com>
Reviewed-by: Lukasz Luba <lukasz.luba@arm.com>
Reviewed-by: Donald Hunter <donald.hunter@gmail.com>
Signed-off-by: Changwoo Min <changwoo@igalia.com>
Link: https://patch.msgid.link/20260108053212.642478-5-changwoo@igalia.com
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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Previously, the cpus attribute was a string format which was a "%*pb"
stringification of a bitmap. That is not very consumable for a UAPI,
so let’s change it to an u64 array of CPU ids.
Suggested-by: Donald Hunter <donald.hunter@gmail.com>
Reviewed-by: Lukasz Luba <lukasz.luba@arm.com>
Reviewed-by: Donald Hunter <donald.hunter@gmail.com>
Signed-off-by: Changwoo Min <changwoo@igalia.com>
Link: https://patch.msgid.link/20260108053212.642478-4-changwoo@igalia.com
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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The EM YNL specification used many acronyms, including ‘em’, ‘pd’,
‘ps’, etc. While the acronyms are short and convenient, they could be
confusing. So, let’s spell them out to be more specific. The following
changes were made in the spec. Note that the protocol name cannot exceed
GENL_NAMSIZ (16).
em -> dev-energymodel
pds -> perf-domains
pd -> perf-domain
pd-id -> perf-domain-id
pd-table -> perf-table
ps -> perf-state
get-pds -> get-perf-domains
get-pd-table -> get-perf-table
pd-created -> perf-domain-created
pd-updated -> perf-domain-updated
pd-deleted -> perf-domain-deleted
In addition. doc strings were added to the spec. based on the comments in
energy_model.h. Two flag attributes (perf-state-flags and
perf-domain-flags) were added for easily interpreting the bit flags.
Finally, the autogenerated files and em_netlink.c were updated accordingly
to reflect the name changes.
Suggested-by: Donald Hunter <donald.hunter@gmail.com>
Reviewed-by: Lukasz Luba <lukasz.luba@arm.com>
Reviewed-by: Donald Hunter <donald.hunter@gmail.com>
Signed-off-by: Changwoo Min <changwoo@igalia.com>
Link: https://patch.msgid.link/20260108053212.642478-3-changwoo@igalia.com
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm
Pull power management fix from Rafael Wysocki:
"This fixes a crash in the hibernation image saving code that can be
triggered when the given compression algorithm is unavailable (Malaya
Kumar Rout)"
* tag 'pm-6.19-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
PM: hibernate: Fix crash when freeing invalid crypto compressor
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sched_mm_cid_after_execve() is called in bprm_execve()'s cleanup path even
when exec_binprm() fails. For the init task's first execve(), this causes a
problem:
1. current->mm is NULL (kernel threads don't have an mm)
2. sched_mm_cid_before_execve() exits early because mm is NULL
3. exec_binprm() fails (e.g., ENOENT for missing script interpreter)
4. sched_mm_cid_after_execve() is called with mm still NULL
5. sched_mm_cid_fork() is called unconditionally, triggering WARN_ON
This is easily reproduced by booting with an init that is a shell script
(#!/bin/sh) where the interpreter doesn't exist in the initramfs.
Fix this by checking if t->mm is NULL before calling sched_mm_cid_fork(),
matching the behavior of sched_mm_cid_before_execve() which already
handles this case via sched_mm_cid_exit()'s early return.
Fixes: b0c3d51b54f8 ("sched/mmcid: Provide precomputed maximal value")
Signed-off-by: Cong Wang <cwang@multikernel.io>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Reviewed-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Acked-by: Will Deacon <will@kernel.org>
Link: https://patch.msgid.link/20251223215113.639686-1-xiyou.wangcong@gmail.com
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When ida_alloc() fails in em_create_pd(), the function returns without
freeing the previously allocated 'pd' structure, leading to a memory leak.
The 'pd' pointer is allocated either at line 436 (for CPU devices with
cpumask) or line 442 (for other devices) using kzalloc().
Additionally, the function incorrectly returns -ENOMEM when ida_alloc()
fails, ignoring the actual error code returned by ida_alloc(), which can
fail for reasons other than memory exhaustion.
Fix both issues by:
1. Freeing the 'pd' structure with kfree() when ida_alloc() fails
2. Returning the actual error code from ida_alloc() instead of -ENOMEM
This ensures proper cleanup on the error path and accurate error reporting.
Fixes: cbe5aeedecc7 ("PM: EM: Assign a unique ID when creating a performance domain")
Signed-off-by: Malaya Kumar Rout <mrout@redhat.com>
Reviewed-by: Changwoo Min <changwoo@igalia.com>
Link: https://patch.msgid.link/20260105103730.65626-1-mrout@redhat.com
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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The introduction of PREEMPT_LAZY was for multiple reasons:
- PREEMPT_RT suffered from over-scheduling, hurting performance compared to
!PREEMPT_RT.
- the introduction of (more) features that rely on preemption; like
folio_zero_user() which can do large memset() without preemption checks.
(Xen already had a horrible hack to deal with long running hypercalls)
- the endless and uncontrolled sprinkling of cond_resched() -- mostly cargo
cult or in response to poor to replicate workloads.
By moving to a model that is fundamentally preemptable these things become
managable and avoid needing to introduce more horrible hacks.
Since this is a requirement; limit PREEMPT_NONE to architectures that do not
support preemption at all. Further limit PREEMPT_VOLUNTARY to those
architectures that do not yet have PREEMPT_LAZY support (with the eventual goal
to make this the empty set and completely remove voluntary preemption and
cond_resched() -- notably VOLUNTARY is already limited to !ARCH_NO_PREEMPT.)
This leaves up-to-date architectures (arm64, loongarch, powerpc, riscv, s390,
x86) with only two preemption models: full and lazy.
While Lazy has been the recommended setting for a while, not all distributions
have managed to make the switch yet. Force things along. Keep the patch minimal
in case of hard to address regressions that might pop up.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Valentin Schneider <vschneid@redhat.com>
Link: https://patch.msgid.link/20251219101502.GB1132199@noisy.programming.kicks-ass.net
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This colocates some hot fields in "struct rq" to be on the same cache line
as others that are often accessed at the same time or in similar ways.
Using data from a Google-internal fleet-scale profiler, I found three
distinct groups of hot fields in struct rq:
- (1) The runqueue lock: __lock.
- (2) Those accessed from hot code in pick_next_task_fair():
nr_running, nr_numa_running, nr_preferred_running,
ttwu_pending, cpu_capacity, curr, idle.
- (3) Those accessed from some other hot codepaths, e.g.
update_curr(), update_rq_clock(), and scheduler_tick():
clock_task, clock_pelt, clock, lost_idle_time,
clock_update_flags, clock_pelt_idle, clock_idle.
The cycles spent on accessing these different groups of fields broke down
roughly as follows:
- 50% on group (1) (the runqueue lock, always read-write)
- 39% on group (2) (load:store ratio around 38:1)
- 8% on group (3) (load:store ratio around 5:1)
- 3% on all the other fields
Most of the fields in group (3) are already in a cache line grouping; this
patch just adds "clock" and "clock_update_flags" to that group. The fields
in group (2) are scattered across several cache lines; the main effect of
this patch is to group them together, on a single line at the beginning of
the structure. A few other less performance-critical fields (nr_switches,
numa_migrate_on, has_blocked_load, nohz_csd, last_blocked_load_update_tick)
were also reordered to reduce holes in the data structure.
Since the runqueue lock is acquired from so many different contexts, and is
basically always accessed using an atomic operation, putting it on either
of the cache lines for groups (2) or (3) would slow down accesses to those
fields dramatically, since those groups are read-mostly accesses.
To test this, I wrote a focused load test that would put load on the
pick_next_task_fair() path. A parent process would fork many child
processes, and each child would nanosleep() for 1 msec many times in a
loop. The load test was monitored with "perf", and I looked at the amount
of cycles that were spent with sched_balance_rq() on the stack. The test
was reliably spending ~5% of all of its cycles there. I ran it 100 times
on a pair of 2-socket Intel Haswell machines (72 vCPUs per machine) - one
running the tip of sched/core, the other running this change - using 360
child processes and 8192 1-msec sleeps per child. The mean cycle count
dropped from 5.14B to 4.91B, or a *4.6% decrease* in relevant scheduler
cycles.
Given that this change reduces cache misses in a very hot kernel codepath,
there's likely to be additional application performance improvement due to
reduced cache conflicts from kernel data structures.
On a Power11 system with 128-byte cache lines, my test showed a ~5%
decrease in relevant scheduler cycles, along with a slight increase in user
time - both positive indicators. This data comes from
https://lore.kernel.org/lkml/affdc6b1-9980-44d1-89db-d90730c1e384@linux.ibm.com/
This is the case even though the additional "____cacheline_aligned" that
puts the runqueue lock on the next cache line adds an additional 64 bytes
of padding on those machines. This patch does not change the size of
"struct rq" on machines with 64-byte cache lines.
I also ran "hackbench" to try to test this change, but it didn't show
conclusive results. Looking at a CPU cycle profile of the hackbench run,
it was spending 95% of its cycles inside __alloc_skb(), __kfree_skb(), or
kmem_cache_free() - almost all of which was spent updating memcg counters
or contending on the list_lock in kmem_cache_node. And it spent less than
0.5% of its cycles inside either schedule() or try_to_wake_up(). So it's
not surprising that it didn't show useful results here.
The "__no_randomize_layout" was added to reflect the fact that performance
of code that references this data structure is unusually sensitive to
placement of its members.
Signed-off-by: Blake Jones <blakejones@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Madadi Vineeth Reddy <vineethr@linux.ibm.com>
Reviewed-by: Josh Don <joshdon@google.com>
Tested-by: Madadi Vineeth Reddy <vineethr@linux.ibm.com>
Link: https://patch.msgid.link/20251202023743.1524247-1-blakejones@google.com
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In the group_has_spare case, the function creates a temporary cpumask
to just calculate weight of (p->cpus_ptr & sched_group_span(local)).
We've got a dedicated helper for it.
Signed-off-by: Yury Norov (NVIDIA) <yury.norov@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Reviewed-by: K Prateek Nayak <kprateek.nayak@amd.com>
Reviewed-by: Fernand Sieber <sieberf@amazon.com>
Link: https://patch.msgid.link/20251207034247.402926-1-yury.norov@gmail.com
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Use for_each_cpu_and() and drop some housekeeping code.
Signed-off-by: Yury Norov (NVIDIA) <yury.norov@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: K Prateek Nayak <kprateek.nayak@amd.com>
Reviewed-by: Phil Auld <pauld@redhat.com>
Link: https://patch.msgid.link/20251207033037.399608-1-yury.norov@gmail.com
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cpumask_empty() call is O(N) and useless because the previous
cpumask_and() returns false for empty 'cpus'. Drop it.
Signed-off-by: Yury Norov (NVIDIA) <yury.norov@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Madadi Vineeth Reddy <vineethr@linux.ibm.com>
Reviewed-by: K Prateek Nayak <kprateek.nayak@amd.com>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://patch.msgid.link/20251207040543.407695-1-yury.norov@gmail.com
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BPF_MAP_TYPE_INSN_ARRAY maps store instruction pointers in their
ips array, not string data. The map_direct_value_addr callback for
this map type returns the address of the ips array, which is not
suitable for use as a constant string argument.
When a BPF program passes a pointer to an insn_array map value as
ARG_PTR_TO_CONST_STR (e.g., to bpf_snprintf), the verifier's
null-termination check in check_reg_const_str() operates on the
wrong memory region, and at runtime bpf_bprintf_prepare() can read
out of bounds searching for a null terminator.
Reject BPF_MAP_TYPE_INSN_ARRAY in check_reg_const_str() since this
map type is not designed to hold string data.
Reported-by: syzbot+2c29addf92581b410079@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=2c29addf92581b410079
Tested-by: syzbot+2c29addf92581b410079@syzkaller.appspotmail.com
Fixes: 493d9e0d6083 ("bpf, x86: add support for indirect jumps")
Signed-off-by: Deepanshu Kartikey <kartikey406@gmail.com>
Acked-by: Anton Protopopov <a.s.protopopov@gmail.com>
Link: https://lore.kernel.org/r/20260107021037.289644-1-kartikey406@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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The cgrp_ancestor_storage has two drawbacks:
- it's not guaranteed that the member immediately follows struct cgrp in
cgroup_root (root cgroup's ancestors[0] might thus point to a padding
and not in cgrp_ancestor_storage proper),
- this idiom raises warnings with -Wflex-array-member-not-at-end.
Instead of relying on the auxiliary member in cgroup_root, define the
0-th level ancestor inside struct cgroup (needed for static allocation
of cgrp_dfl_root), deeper cgroups would allocate flexible
_low_ancestors[]. Unionized alias through ancestors[] will
transparently join the two ranges.
The above change would still leave the flexible array at the end of
struct cgroup inside cgroup_root, so move cgrp also towards the end of
cgroup_root to resolve the -Wflex-array-member-not-at-end.
Link: https://lore.kernel.org/r/5fb74444-2fbb-476e-b1bf-3f3e279d0ced@embeddedor.com/
Reported-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Closes: https://lore.kernel.org/r/b3eb050d-9451-4b60-b06c-ace7dab57497@embeddedor.com/
Cc: David Laight <david.laight.linux@gmail.com>
Acked-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Signed-off-by: Michal Koutný <mkoutny@suse.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
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The ftrace_dump_on_oops string is not used outside of trace.c so
make it static to avoid the export warning from sparse:
kernel/trace/trace.c:141:6: warning: symbol 'ftrace_dump_on_oops' was not declared. Should it be static?
Fixes: dd293df6395a2 ("tracing: Move trace sysctls into trace.c")
Link: https://patch.msgid.link/20260106231054.84270-1-ben.dooks@codethink.co.uk
Signed-off-by: Ben Dooks <ben.dooks@codethink.co.uk>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
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A bug was reported about an infinite recursion caused by tracing the rcu
events with the kernel stack trace trigger enabled. The stack trace code
called back into RCU which then called the stack trace again.
Expand the ftrace recursion protection to add a set of bits to protect
events from recursion. Each bit represents the context that the event is
in (normal, softirq, interrupt and NMI).
Have the stack trace code use the interrupt context to protect against
recursion.
Note, the bug showed an issue in both the RCU code as well as the tracing
stacktrace code. This only handles the tracing stack trace side of the
bug. The RCU fix will be handled separately.
Link: https://lore.kernel.org/all/20260102122807.7025fc87@gandalf.local.home/
Cc: stable@vger.kernel.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: "Paul E. McKenney" <paulmck@kernel.org>
Cc: Boqun Feng <boqun.feng@gmail.com>
Link: https://patch.msgid.link/20260105203141.515cd49f@gandalf.local.home
Reported-by: Yao Kai <yaokai34@huawei.com>
Tested-by: Yao Kai <yaokai34@huawei.com>
Fixes: 5f5fa7ea89dc ("rcu: Don't use negative nesting depth in __rcu_read_unlock()")
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
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When user resize all trace ring buffer through file 'buffer_size_kb',
then in ring_buffer_resize(), kernel allocates buffer pages for each
cpu in a loop.
If the kernel preemption model is PREEMPT_NONE and there are many cpus
and there are many buffer pages to be freed, it may not give up cpu
for a long time and finally cause a softlockup.
To avoid it, call cond_resched() after each cpu buffer free as Commit
f6bd2c92488c ("ring-buffer: Avoid softlockup in ring_buffer_resize()")
does.
Detailed call trace as follow:
rcu: INFO: rcu_sched self-detected stall on CPU
rcu: 24-....: (14837 ticks this GP) idle=521c/1/0x4000000000000000 softirq=230597/230597 fqs=5329
rcu: (t=15004 jiffies g=26003221 q=211022 ncpus=96)
CPU: 24 UID: 0 PID: 11253 Comm: bash Kdump: loaded Tainted: G EL 6.18.2+ #278 NONE
pc : arch_local_irq_restore+0x8/0x20
arch_local_irq_restore+0x8/0x20 (P)
free_frozen_page_commit+0x28c/0x3b0
__free_frozen_pages+0x1c0/0x678
___free_pages+0xc0/0xe0
free_pages+0x3c/0x50
ring_buffer_resize.part.0+0x6a8/0x880
ring_buffer_resize+0x3c/0x58
__tracing_resize_ring_buffer.part.0+0x34/0xd8
tracing_resize_ring_buffer+0x8c/0xd0
tracing_entries_write+0x74/0xd8
vfs_write+0xcc/0x288
ksys_write+0x74/0x118
__arm64_sys_write+0x24/0x38
Cc: <mathieu.desnoyers@efficios.com>
Link: https://patch.msgid.link/20251228065008.2396573-1-mawupeng1@huawei.com
Signed-off-by: Wupeng Ma <mawupeng1@huawei.com>
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
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soft_mode is not read in the enable case, so drop the assignment.
Drop also the comment text that refers to the assignment and realign
the comment.
Cc: "Paul E . McKenney" <paulmck@kernel.org>
Cc: Gabriele Paoloni <gpaoloni@redhat.com>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Link: https://patch.msgid.link/20251226110531.4129794-1-Julia.Lawall@inria.fr
Signed-off-by: Julia Lawall <Julia.Lawall@inria.fr>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
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For use the init_srcu_struct*() to initialized srcu structure,
the srcu structure's->srcu_sup and sda use GFP_KERNEL flags to
allocate memory. similarly, if set SRCU_SIZING_INIT, the
srcu_sup's->node can still use GFP_KERNEL flags to allocate
memory, not need to use GFP_ATOMIC flags all the time.
Signed-off-by: Zqiang <qiang.zhang@linux.dev>
Reviewed-by: Joel Fernandes <joelagnelf@nvidia.com>
Tested-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Joel Fernandes <joelagnelf@nvidia.com>
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
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Commit 5f5fa7ea89dc ("rcu: Don't use negative nesting depth in
__rcu_read_unlock()") removes the recursion-protection code from
__rcu_read_unlock(). Therefore, we could invoke the deadloop in
raise_softirq_irqoff() with ftrace enabled as follows:
WARNING: CPU: 0 PID: 0 at kernel/trace/trace.c:3021 __ftrace_trace_stack.constprop.0+0x172/0x180
Modules linked in: my_irq_work(O)
CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Tainted: G O 6.18.0-rc7-dirty #23 PREEMPT(full)
Tainted: [O]=OOT_MODULE
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014
RIP: 0010:__ftrace_trace_stack.constprop.0+0x172/0x180
RSP: 0018:ffffc900000034a8 EFLAGS: 00010002
RAX: 0000000000000000 RBX: 0000000000000004 RCX: 0000000000000000
RDX: 0000000000000003 RSI: ffffffff826d7b87 RDI: ffffffff826e9329
RBP: 0000000000090009 R08: 0000000000000005 R09: ffffffff82afbc4c
R10: 0000000000000008 R11: 0000000000011d7a R12: 0000000000000000
R13: ffff888003874100 R14: 0000000000000003 R15: ffff8880038c1054
FS: 0000000000000000(0000) GS:ffff8880fa8ea000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055b31fa7f540 CR3: 00000000078f4005 CR4: 0000000000770ef0
PKRU: 55555554
Call Trace:
<IRQ>
trace_buffer_unlock_commit_regs+0x6d/0x220
trace_event_buffer_commit+0x5c/0x260
trace_event_raw_event_softirq+0x47/0x80
raise_softirq_irqoff+0x6e/0xa0
rcu_read_unlock_special+0xb1/0x160
unwind_next_frame+0x203/0x9b0
__unwind_start+0x15d/0x1c0
arch_stack_walk+0x62/0xf0
stack_trace_save+0x48/0x70
__ftrace_trace_stack.constprop.0+0x144/0x180
trace_buffer_unlock_commit_regs+0x6d/0x220
trace_event_buffer_commit+0x5c/0x260
trace_event_raw_event_softirq+0x47/0x80
raise_softirq_irqoff+0x6e/0xa0
rcu_read_unlock_special+0xb1/0x160
unwind_next_frame+0x203/0x9b0
__unwind_start+0x15d/0x1c0
arch_stack_walk+0x62/0xf0
stack_trace_save+0x48/0x70
__ftrace_trace_stack.constprop.0+0x144/0x180
trace_buffer_unlock_commit_regs+0x6d/0x220
trace_event_buffer_commit+0x5c/0x260
trace_event_raw_event_softirq+0x47/0x80
raise_softirq_irqoff+0x6e/0xa0
rcu_read_unlock_special+0xb1/0x160
unwind_next_frame+0x203/0x9b0
__unwind_start+0x15d/0x1c0
arch_stack_walk+0x62/0xf0
stack_trace_save+0x48/0x70
__ftrace_trace_stack.constprop.0+0x144/0x180
trace_buffer_unlock_commit_regs+0x6d/0x220
trace_event_buffer_commit+0x5c/0x260
trace_event_raw_event_softirq+0x47/0x80
raise_softirq_irqoff+0x6e/0xa0
rcu_read_unlock_special+0xb1/0x160
__is_insn_slot_addr+0x54/0x70
kernel_text_address+0x48/0xc0
__kernel_text_address+0xd/0x40
unwind_get_return_address+0x1e/0x40
arch_stack_walk+0x9c/0xf0
stack_trace_save+0x48/0x70
__ftrace_trace_stack.constprop.0+0x144/0x180
trace_buffer_unlock_commit_regs+0x6d/0x220
trace_event_buffer_commit+0x5c/0x260
trace_event_raw_event_softirq+0x47/0x80
__raise_softirq_irqoff+0x61/0x80
__flush_smp_call_function_queue+0x115/0x420
__sysvec_call_function_single+0x17/0xb0
sysvec_call_function_single+0x8c/0xc0
</IRQ>
Commit b41642c87716 ("rcu: Fix rcu_read_unlock() deadloop due to IRQ work")
fixed the infinite loop in rcu_read_unlock_special() for IRQ work by
setting a flag before calling irq_work_queue_on(). We fix this issue by
setting the same flag before calling raise_softirq_irqoff() and rename the
flag to defer_qs_pending for more common.
Fixes: 5f5fa7ea89dc ("rcu: Don't use negative nesting depth in __rcu_read_unlock()")
Reported-by: Tengda Wu <wutengda2@huawei.com>
Signed-off-by: Yao Kai <yaokai34@huawei.com>
Reviewed-by: Joel Fernandes <joelagnelf@nvidia.com>
Tested-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Joel Fernandes <joelagnelf@nvidia.com>
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
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Lack of parentheses causes the ->exp_current() function, for example,
srcu_expedite_current(), to be called only once in four billion times
instead of the intended once in 256 times. This commit therefore adds
the needed parentheses.
Reported-by: Chris Mason <clm@meta.com>
Reported-by: Joel Fernandes <joelagnelf@nvidia.com>
Fixes: 950063c6e897 ("rcutorture: Test srcu_expedite_current()")
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
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If an expedited RCU CPU stall ends just at the stall-warning timeout,
the current code will print an expedited stall-warning message, but one
that doesn't identify any CPUs or tasks causing the stall. This is most
likely to happen for short-timeout stalls, for example, the 20-millisecond
timeouts that are sometimes used for small embedded devices. Needless to
say, these semi-empty stall-warning messages can be rather confusing.
One option would be to suppress the stall-warning message entirely in
this case, but the near-miss information can be quite valuable.
Detect this race condition and emits a "INFO: Expedited stall ended
before state dump start" message to clarify matters.
[boqun: Apply feedback from Borislav]
Reported-by: Borislav Petkov <bp@alien8.de>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Acked-by: Borislav Petkov (AMD) <bp@alien8.de>
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
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percpu_cgroup_storage maps
Introduce BPF_F_ALL_CPUS flag support for percpu_cgroup_storage maps to
allow updating values for all CPUs with a single value for update_elem
API.
Introduce BPF_F_CPU flag support for percpu_cgroup_storage maps to
allow:
* update value for specified CPU for update_elem API.
* lookup value for specified CPU for lookup_elem API.
The BPF_F_CPU flag is passed via map_flags along with embedded cpu info.
Signed-off-by: Leon Hwang <leon.hwang@linux.dev>
Link: https://lore.kernel.org/r/20260107022022.12843-6-leon.hwang@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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Copy map value using 'copy_map_value_long()'. It's to keep consistent
style with the way of other percpu maps.
No functional change intended.
Signed-off-by: Leon Hwang <leon.hwang@linux.dev>
Link: https://lore.kernel.org/r/20260107022022.12843-5-leon.hwang@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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lru_percpu_hash maps
Introduce BPF_F_ALL_CPUS flag support for percpu_hash and lru_percpu_hash
maps to allow updating values for all CPUs with a single value for both
update_elem and update_batch APIs.
Introduce BPF_F_CPU flag support for percpu_hash and lru_percpu_hash
maps to allow:
* update value for specified CPU for both update_elem and update_batch
APIs.
* lookup value for specified CPU for both lookup_elem and lookup_batch
APIs.
The BPF_F_CPU flag is passed via:
* map_flags along with embedded cpu info.
* elem_flags along with embedded cpu info.
Signed-off-by: Leon Hwang <leon.hwang@linux.dev>
Link: https://lore.kernel.org/r/20260107022022.12843-4-leon.hwang@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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Introduce support for the BPF_F_ALL_CPUS flag in percpu_array maps to
allow updating values for all CPUs with a single value for both
update_elem and update_batch APIs.
Introduce support for the BPF_F_CPU flag in percpu_array maps to allow:
* update value for specified CPU for both update_elem and update_batch
APIs.
* lookup value for specified CPU for both lookup_elem and lookup_batch
APIs.
The BPF_F_CPU flag is passed via:
* map_flags of lookup_elem and update_elem APIs along with embedded cpu
info.
* elem_flags of lookup_batch and update_batch APIs along with embedded
cpu info.
Signed-off-by: Leon Hwang <leon.hwang@linux.dev>
Link: https://lore.kernel.org/r/20260107022022.12843-3-leon.hwang@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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Introduce BPF_F_CPU and BPF_F_ALL_CPUS flags and check them for
following APIs:
* 'map_lookup_elem()'
* 'map_update_elem()'
* 'generic_map_lookup_batch()'
* 'generic_map_update_batch()'
And, get the correct value size for these APIs.
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Leon Hwang <leon.hwang@linux.dev>
Link: https://lore.kernel.org/r/20260107022022.12843-2-leon.hwang@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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Leverage ARCH_HAS_DMA_MAP_DIRECT config option for coherent allocations as
well. This will bypass DMA ops for memory allocations that have been
pre-mapped.
Always set device bus_dma_limit when memory is pre-mapped. In some
architectures, like PowerPC, pmemory can be converted to regular memory via
daxctl command. This will gate the coherent allocations to pre-mapped RAM
only, by dma_coherent_ok().
Signed-off-by: Gaurav Batra <gbatra@linux.ibm.com>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/20251107161105.85999-1-gbatra@linux.ibm.com
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The function set_security_override_from_ctx() has no in-tree callers
since 6.14. Remove it.
Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
[PM: subject tweak, merge fuzz]
Signed-off-by: Paul Moore <paul@paul-moore.com>
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The bpf_arena_*_pages() kfuncs can be called from sleepable contexts,
but the verifier still prevents BPF programs from calling them while
holding a spinlock. Amend the verifier to allow for BPF programs
calling arena page management functions while holding a lock.
Signed-off-by: Emil Tsalapatis <emil@etsalapatis.com>
Link: https://lore.kernel.org/r/20260106-arena-under-lock-v2-2-378e9eab3066@etsalapatis.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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The in_sleepable_context() function is used to specialize the BPF code
in do_misc_fixups(). With the addition of nonsleepable arena kfuncs,
there are kfuncs whose specialization depends on whether we are
holding a lock. We should use the nonsleepable version while
holding a lock and the sleepable one when not.
Add a check for active_locks to account for locking when specializing
arena kfuncs.
Signed-off-by: Emil Tsalapatis <emil@etsalapatis.com>
Link: https://lore.kernel.org/r/20260106-arena-under-lock-v2-1-378e9eab3066@etsalapatis.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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Replace deprecated kmap_atomic() with kmap_local_page().
Signed-off-by: Keke Ming <ming.jvle@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Oleg Nesterov <oleg@redhat.com>
Link: https://patch.msgid.link/20260103084243.195125-6-ming.jvle@gmail.com
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When crypto_alloc_acomp() fails, it returns an ERR_PTR value, not NULL.
The cleanup code in save_compressed_image() and load_compressed_image()
unconditionally calls crypto_free_acomp() without checking for ERR_PTR,
which causes crypto_acomp_tfm() to dereference an invalid pointer and
crash the kernel.
This can be triggered when the compression algorithm is unavailable
(e.g., CONFIG_CRYPTO_LZO not enabled).
Fix by adding IS_ERR_OR_NULL() checks before calling crypto_free_acomp()
and acomp_request_free(), similar to the existing kthread_stop() check.
Fixes: b03d542c3c95 ("PM: hibernate: Use crypto_acomp interface")
Signed-off-by: Malaya Kumar Rout <mrout@redhat.com>
Cc: 6.15+ <stable@vger.kernel.org> # 6.15+
[ rjw: Added 2 empty code lines ]
Link: https://patch.msgid.link/20251230115613.64080-1-mrout@redhat.com
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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This demonstrates a larger conversion to use Clang's context
analysis. The benefit is additional static checking of locking rules,
along with better documentation.
Notably, kernel/sched contains sufficiently complex synchronization
patterns, and application to core.c & fair.c demonstrates that the
latest Clang version has become powerful enough to start applying this
to more complex subsystems (with some modest annotations and changes).
Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20251219154418.3592607-37-elver@google.com
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With Sparse support gone, Clang is a bit more strict and warns:
./include/linux/console.h:492:50: error: use of undeclared identifier 'console_mutex'
492 | extern void console_list_unlock(void) __releases(console_mutex);
Since it does not make sense to make console_mutex itself global, move
the annotation to printk.c. Context analysis remains disabled for
printk.c.
This is needed to enable context analysis for modules that include
<linux/console.h>.
Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20251219154418.3592607-34-elver@google.com
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Enable context analysis for the KCSAN subsystem.
Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20251219154418.3592607-31-elver@google.com
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Enable context analysis for the KCOV subsystem.
Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20251219154418.3592607-30-elver@google.com
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As discussed in [1], removing __cond_lock() will improve the readability
of trylock code. Now that Sparse context tracking support has been
removed, we can also remove __cond_lock().
Change existing APIs to either drop __cond_lock() completely, or make
use of the __cond_acquires() function attribute instead.
In particular, spinlock and rwlock implementations required switching
over to inline helpers rather than statement-expressions for their
trylock_* variants.
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/all/20250207082832.GU7145@noisy.programming.kicks-ass.net/ [1]
Link: https://patch.msgid.link/20251219154418.3592607-25-elver@google.com
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With the change to hrtimer_try_to_cancel() in
perf_swevent_cancel_hrtimer() it appears possible for the hrtimer to
still be active by the time the event gets freed.
Make sure the event does a full hrtimer_cancel() on the free path by
installing a perf_event::destroy handler.
Fixes: eb3182ef0405 ("perf/core: Fix system hang caused by cpu-clock usage")
Reported-by: CyberUnicorns <a101e_iotvul@163.com>
Tested-by: CyberUnicorns <a101e_iotvul@163.com>
Debugged-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
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