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Thu, 27 Feb 2025 06:42:37 -0800 (PST) Received: from localhost ([2603:7000:c01:2716:da5e:d3ff:fee7:26e7]) by smtp.gmail.com with UTF8SMTPSA id 6a1803df08f44-6e8976537afsm10455616d6.43.2025.02.27.06.42.36 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 27 Feb 2025 06:42:36 -0800 (PST) Date: Thu, 27 Feb 2025 09:42:32 -0500 From: Johannes Weiner To: Jingxiang Zeng Cc: linux-mm@kvack.org, akpm@linux-foundation.org, mhocko@kernel.org, roman.gushchin@linux.dev, shakeel.butt@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: <20250227144232.GE110982@cmpxchg.org> 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-Rspam-User: X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 1CB83120024 X-Stat-Signature: ujzmdn1p3o6fhsqupw5pi1zjyrizgzuu X-HE-Tag: 1740667358-346608 X-HE-Meta: U2FsdGVkX1/gOcoqyzktXV8XF1s0/eSkI65AARcFUz4ek6iq5qPYZcI7H8VKRwlpi5c5Ec2zUt8IZkAhMWzDucYoQfIyEC3e+f1r5aBm+AQdyNjAA31kx8mCNgFBmvhVxL+nsKFHwpyB/bkgSV+jMxLk7p7b3iJfEtaDajVC0dO2Xj+JNkPbbQQWrB35swCoVdaGOChGHB7K/CuONNUQ69lA4Hi6cf3cBs36BbcwzMWk1yj/gFnthE5RpXMYJZvGWabFWT1LgDFjJhtMn+ZfRN6+9aZ5PTrl70AvBadxrLDFS18FEKdyHzAjFwXcejQPNY6GqOJHEFddVm7wyAJSzfG8Ti4eZocIeUG6BbMDZWW0ARDM0wqESDk3bTYclTyPX8J/uvCq5ncAZF6ejvOLl25/gRLjv1LV8XVDP74n92W+N923ZL0sc874JRVd4i893tcPCEJCbK3iHRbLDTmfLfVc4Rg6TqMPFlV0VKbduXfdbWBzGItGI5Y4NQjPA2HQSSNHbU+kgncSwbK0c7OC35YGe0kuKpHGYIfirTPl4bl8DsBjPp0QvSG6jm3KLKXYMNOddYMfpewzoKIc+e/zqLXNW3TX62bQGpzCDKqaMdONQJwKHi4eUf4t5O8Enp1pE4a9IBBbwG+l15VM3iBbvfYw+1P/WMyxRldruZ8o5+DxAul7vB7+2uX521tGmaimCN3qMovSbQ+YrUI+j64KjiD2nLLcanv88xHF4uY63/4InayxU3ZiQavudauRIkl9vf5+zvkcH9bWjBn9UN5aYUbMn8RBXqNJOq9lv/KVIcq0aIudMsQQ/MgfJ+smSEbJ5lRn/s4nfPXOTV0/s4TvKC6DcZ8KYdTUH9BXWsy4T2VocCQCSuMH7w/lNqp5guqQD/0I7ftJN6JcAtc4giNVU3UeeD4VoKE99rflpUnvTMD29hAIHff4rMuTKsOwA3k7xRtOgQweK9BryKwx5tE QqiWM/Fz vPxPmeuJNNC40T3WbjEofsxdEBFjt/qzilmvfj+9xs12gfgXd2Wfk0bFS3qnvUaJ5Va5LihKTLD7ue60xlud6et0RH5QsYg5YXpNLR5SaeexXwU+DNCh/f/P14Plsdvj8UX/cPUEKAhNaaH0E0bk0dkd2r9FyDL+SIZ3h6a25YiUmiP7gFEDzapSdOGuHMip0UzK148Spl97nTr7R83fc8i5SYTMuOV0MEIzZrWRJL+C7vyX89euw8jTi73Zcb2QZ1ZLuUlKXOhtt8MmTo5+vC5yKJGgZqrtzNvMxYJ0DSKoIrxa8lFbimZhXm3dWmf0Os9V8jcKtLEBZbK9x7lmgsiD1YV8axiTrZCQMmsv4SMdkyvnet+AnXc+siA87irg2NSvjOG90lz05kBD6SQV4r0hSU48TT/XBnYD+XPnMrbXK8+M7Bl0T92uG3IpdITTlOWkR9YSlXRPujtdhrE3IyJ/9orC98LxuYac5nkks0xAbtghx0ES9hkoFBO5Nt5nEx5/aoKyO+ibG3blJ+yAo321HK7W8RoA1rg9GLebOYupLrYqHEuYpwVnhaRygFFKUbY3OmCUbeIHH9jc6UZb5PcAt7rpG6+YK9Pvh X-Bogosity: Ham, tests=bogofilter, spamicity=0.000025, 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: Johannes Weiner