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From: Shakeel Butt To: Jingxiang Zeng Cc: linux-mm@kvack.org, akpm@linux-foundation.org, hannes@cmpxchg.org, mhocko@kernel.org, roman.gushchin@linux.dev, muchun.song@linux.dev, chengming.zhou@linux.dev, kasong@tencent.com, lkp@intel.com Subject: Re: [PATCH V1] mm/list_lru: make the case where mlru is NULL as unlikely Message-ID: References: <20250227082223.1173847-1-jingxiangzeng.cas@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250227082223.1173847-1-jingxiangzeng.cas@gmail.com> X-Migadu-Flow: FLOW_OUT X-Rspam-User: X-Stat-Signature: e5ixmsxirwcbe8mj1bgoo1a95c5abr1b X-Rspamd-Queue-Id: E14791A0019 X-Rspamd-Server: rspam07 X-HE-Tag: 1740682454-776001 X-HE-Meta: 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 pTxiv8ce jyvb0wvKzuvEJ03PK75DV8m2AN///kDv4G4h5tqpkEH3Txz7b5OCqyJqnmIsLmuhbnFmKmw/R1b0cevWN+/9Da+H+T7Mz1BU4/wb/5PvWuguhdcktsL7oJbq4d9Vug4zyUPILv8e5WrY5CqZcburZgksvzisCdaaK0qq/B/crvjgUv42xO6MsJ3KHDqjtPUhpvij0SQKlY7/0zY9yRxBDCFi2EB3MrvAgSw4jyrFho1tyhr1AQ0aq9bKc9qWB859/1ppcR34h7wDaAoWPh0Jpq9j7AxbJdR61peECWks6QTJipE6AHn4VkN4jxsw0MwWb4TBIGwFCrWEhZnLUuqgzfeOY0kIZs0IoxzuS7Cx8IeJYxEc= 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, Feb 27, 2025 at 04:22:23PM +0800, Jingxiang Zeng wrote: > From: Zeng Jingxiang > > In the following memcg_list_lru_alloc() function, mlru here is almost > always NULL, so in most cases this should save a function call, mark > mlru as unlikely to optimize the code, and reusing the mlru for the > next attempt when the tree insertion fails. > do { > xas_lock_irqsave(&xas, flags); > if (!xas_load(&xas) && !css_is_dying(&pos->css)) { > xas_store(&xas, mlru); > if (!xas_error(&xas)) > mlru = NULL; > } > xas_unlock_irqrestore(&xas, flags); > } while (xas_nomem(&xas, GFP_KERNEL)); > > if (mlru) > kfree(mlru); > > Reported-by: kernel test robot > Closes: https://lore.kernel.org/oe-kbuild-all/202412290924.UTP7GH2Z-lkp@intel.com/ > Signed-off-by: Zeng Jingxiang > Suggested-by: Johannes Weiner Acked-by: Shakeel Butt