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Howlett" , Kiryl Shutsemau , Vlastimil Babka , Kairui Song , Mikhail Zaslonko , Vasily Gorbik , Baolin Wang , Barry Song , Dev Jain , Lance Yang , Nico Pache , Ryan Roberts , cgroups@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20260527204757.2544958-1-hannes@cmpxchg.org> <20260527204757.2544958-2-hannes@cmpxchg.org> Content-Language: en-US X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Usama Arif In-Reply-To: <20260527204757.2544958-2-hannes@cmpxchg.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Migadu-Flow: FLOW_OUT X-Stat-Signature: ytmpupewom3uemecynrot6apczxikkz8 X-Rspamd-Queue-Id: 6D44E18000A X-Rspamd-Server: rspam07 X-Rspam-User: X-HE-Tag: 1779974720-210126 X-HE-Meta: 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 SxZWugzQ C7ZPpdo3uIYW3NI2eurbUidLQVdRTt1AQzjV/7g7RjyykpbqTZ9DkW0yDNvXskt35sVB/OyChaPBjgF0hhR10oruet2Ml6FfvyqsSWwqQGNPurw1LHajW1yJGKVMFfKOyWQ+uNk4Lo4z7FUvxXpkzdAGU7OOYvyIDZN1nz3mJ5DP2T08ZO2XjgXXtgcc4I3pph1ncUOjdGsS1vpwW4NJMagCeaxa3LYJrx4FJvkh0lzAD2FlsuyICeVKeO10t2MQ0fh0lJ3B+YVPOyxFLAdEOMGtKnnhDOOFsmJDz0jxE/fnk1IBCKd7Pr8q92Bln3dCrgUsW Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 27/05/2026 21:45, Johannes Weiner wrote: > When list_lru_add() races with cgroup deletion, the shrinker bit is set > on the wrong group and lost. This can cause a shrinker run to miss the > cgroup that actually has the object. > > When the passed in memcg is dead, the function finds the first non-dead > parent from the passed in memcg and adds the object there; but the > shrinker bit is set on the memcg that was passed in. > > This bug is as old as the shrinker bitmap itself. > > Fix it by returning the "effective" memcg from the locking function, and > have the caller use that. > > Fixes: fae91d6d8be5 ("mm/list_lru.c: set bit in memcg shrinker bitmap on first list_lru item appearance") > Reported-by: Usama Arif > Reported-by: Sashiko > Signed-off-by: Johannes Weiner > --- > mm/list_lru.c | 26 +++++++++++++++----------- > 1 file changed, 15 insertions(+), 11 deletions(-) > Acked-by: Usama Arif