On Thu, Jun 27, 2024 at 01:17:37PM -0700, Nhat Pham wrote:
syzbot detects that cachestat() is flushing stats, which can sleep, in its RCU read section (see [1]). This is done in the workingset_test_recent() step (which checks if the folio's eviction is recent).
Move the stat flushing step to before the RCU read section of cachestat, and skip stat flushing during the recency check.
Reported-by: syzbot+b7f13b2d0cc156edf61a@syzkaller.appspotmail.com Closes: https://lore.kernel.org/cgroups/000000000000f71227061bdf97e0@google.com/ Debugged-by: Johannes Weiner hannes@cmpxchg.org Suggested-by: Johannes Weiner hannes@cmpxchg.org Signed-off-by: Nhat Pham nphamcs@gmail.com Fixes: b00684722262 ("mm: workingset: move the stats flush into workingset_test_recent()") Cc: stable@vger.kernel.org # v6.8+
Acked-by: Johannes Weiner hannes@cmpxchg.org