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From: Shakeel Butt To: Johannes Weiner Cc: Andrew Morton , David Hildenbrand , Yosry Ahmed , Zi Yan , "Liam R. Howlett" , Usama Arif , Kiryl Shutsemau , Dave Chinner , Roman Gushchin , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v3 1/7] mm: list_lru: lock_list_lru_of_memcg() cannot return NULL if !skip_empty Message-ID: References: <20260318200352.1039011-1-hannes@cmpxchg.org> <20260318200352.1039011-2-hannes@cmpxchg.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260318200352.1039011-2-hannes@cmpxchg.org> X-Migadu-Flow: FLOW_OUT X-Stat-Signature: 79a56ngr1jfg9sopyxrwz8qyu1tqe78z X-Rspamd-Server: rspam09 X-Rspam-User: X-Rspamd-Queue-Id: 0C57E18000C X-HE-Tag: 1773864786-705323 X-HE-Meta: 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 UY+D2GHP 3lW8qx1Ehddzbu/JhlnSWOccZfl0+t4w1itI9lEpWJyMjwuk4v38szb+WAg+W3LWwY/6EKG9KxJUELxK77613UPpWeOrQgPdWoUshYp3AxcfyABw/agsmIdX+h58Jra/VPH7WqyRNAhLKmkxpBAu52Qz3JbOcKjnhNaGRZ260365opl1eYCNWKCttNx95/X3zr1E5MWaz4m0MT5cLdBLPpP+YMX4njFpazh5lL3BbeAWMpq3PIUKLSHA3pb0jCGV6JYcATtroM6zNrRMBoVP5o7gjF4ZmsbYMg0DzJViLPAzrwNcHn2kdUJJvgTdvY0+8I29xZb840c5qF4JohJ6UstozrIziBUnYh82jLeayxBDxyMJR6sNhHeTBQG+bgY8mCf5L Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Wed, Mar 18, 2026 at 03:53:19PM -0400, Johannes Weiner wrote: > skip_empty is only for the shrinker to abort and skip a list that's > empty or whose cgroup is being deleted. > > For list additions and deletions, the cgroup hierarchy is walked > upwards until a valid list_lru head is found, or it will fall back to > the node list. Acquiring the lock won't fail. Remove the NULL checks > in those callers. > > Reviewed-by: David Hildenbrand (Arm) > Signed-off-by: Johannes Weiner Acked-by: Shakeel Butt