In the Linux kernel, the following vulnerability has been resolved:

cachestat: do not flush stats in recency check

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.

[1]: https://lore.kernel.org/cgroups/000000000000f71227061bdf97e0@google.com/

kernel.org https://git.kernel.org/stable/c/1d1ba14e00d290b1ed616ed78c8c49bf897ce390 [No types assigned]

kernel.org https://git.kernel.org/stable/c/5a4d8944d6b1e1aaaa83ea42c116b520b4ed0394 [No types assigned]