diff options
| author | Nirbhay Sharma <nirbhay.lkd@gmail.com> | 2025-10-03 17:15:55 +0530 |
|---|---|---|
| committer | Tejun Heo <tj@kernel.org> | 2025-10-03 04:30:28 -1000 |
| commit | 93a4b36ef3cf4ce5e6a7e7a7686181de76e246a1 (patch) | |
| tree | 11dd5e49d89e99bfac1166363e4d672243ffeffe /kernel | |
| parent | e406d57be7bd2a4e73ea512c1ae36a40a44e499e (diff) | |
cgroup: Fix seqcount lockdep assertion in cgroup freezer
The commit afa3701c0e45 ("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: afa3701c0e45 ("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>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/cgroup/cgroup.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c index 6ae5f48cf64e..fdee387f0d6b 100644 --- a/kernel/cgroup/cgroup.c +++ b/kernel/cgroup/cgroup.c @@ -5892,7 +5892,7 @@ static struct cgroup *cgroup_create(struct cgroup *parent, const char *name, * if the parent has to be frozen, the child has too. */ cgrp->freezer.e_freeze = parent->freezer.e_freeze; - seqcount_init(&cgrp->freezer.freeze_seq); + seqcount_spinlock_init(&cgrp->freezer.freeze_seq, &css_set_lock); if (cgrp->freezer.e_freeze) { /* * Set the CGRP_FREEZE flag, so when a process will be |