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From: Shakeel Butt To: Nhat Pham Cc: akpm@linux-foundation.org, hannes@cmpxchg.org, kernel-team@meta.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org, willy@infradead.org, david@redhat.com, ryan.roberts@arm.com, ying.huang@intel.com, viro@zeniv.linux.org.uk, kasong@tencent.com, yosryahmed@google.com, linux-fsdevel@vger.kernel.org Subject: Re: [PATCH] cachestat: do not flush stats in recency check Message-ID: References: <000000000000f71227061bdf97e0@google.com> <20240627201737.3506959-1-nphamcs@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240627201737.3506959-1-nphamcs@gmail.com> X-Migadu-Flow: FLOW_OUT X-Stat-Signature: wpw41bfxpzodtx64u4yhxgwbosb6esu1 X-Rspamd-Queue-Id: 0CA2E18000E X-Rspam-User: X-Rspamd-Server: rspam08 X-HE-Tag: 1719539913-114509 X-HE-Meta: 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 80wslUAa 1YdbRgAuo+HETtCqivqoTsvitLNUbl8pytOYpiQCkzYSdTsLOyu58CmMBNg4M6w05tMTLG1YlOJeGl7oZdBv0pNl1Q3lxA8cBAJWygSxm5+Y72Afvoz0R8dzEPoT1ICQ7b/MtUGlxl4ZGTjBdn2selCA3D5bX9JHQST9spaPVuC26wRN6NPZeH8eXgnv5aDq8VAY5/J7okBGPea68g39XShW6Tg4quo05Ud7j3G1QkncMU/g3j62IFO7IzS2s9C9eMfH847ZAg5bl5iKn1J5PyvCmSyhDkhHxE8fqbjMsJ2SyTfrIgY/ZTaqrAoEpadWS4xDW9OwxcYGrwG0+oO/eCH/yXLX6mRmK4QVO X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Thu, Jun 27, 2024 at 01:17:37PM GMT, 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. > > [1]: https://lore.kernel.org/cgroups/000000000000f71227061bdf97e0@google.com/ > > Reported-by: syzbot+b7f13b2d0cc156edf61a@syzkaller.appspotmail.com > Closes: https://lore.kernel.org/cgroups/000000000000f71227061bdf97e0@google.com/ > Debugged-by: Johannes Weiner > Suggested-by: Johannes Weiner > Signed-off-by: Nhat Pham > Fixes: b00684722262 ("mm: workingset: move the stats flush into workingset_test_recent()") > Cc: stable@vger.kernel.org # v6.8+ Acked-by: Shakeel Butt