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Wed, 17 Dec 2025 14:23:37 -0800 (PST) Received: from localhost ([2603:7000:c01:2716:929a:4aff:fe16:c778]) by smtp.gmail.com with ESMTPSA id 6a1803df08f44-88c6117f54bsm4237146d6.45.2025.12.17.14.23.36 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 17 Dec 2025 14:23:37 -0800 (PST) Date: Wed, 17 Dec 2025 17:23:36 -0500 From: Johannes Weiner To: Qi Zheng Cc: hughd@google.com, mhocko@suse.com, roman.gushchin@linux.dev, shakeel.butt@linux.dev, muchun.song@linux.dev, david@kernel.org, lorenzo.stoakes@oracle.com, ziy@nvidia.com, harry.yoo@oracle.com, imran.f.khan@oracle.com, kamalesh.babulal@oracle.com, axelrasmussen@google.com, yuanchu@google.com, weixugc@google.com, chenridong@huaweicloud.com, mkoutny@suse.com, akpm@linux-foundation.org, hamzamahfooz@linux.microsoft.com, apais@linux.microsoft.com, lance.yang@linux.dev, linux-mm@kvack.org, linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, Muchun Song , Qi Zheng Subject: Re: [PATCH v2 16/28] mm: workingset: prevent memory cgroup release in lru_gen_eviction() Message-ID: References: <86b0573753db20e40315c61f5d6e01bdc6a8313a.1765956025.git.zhengqi.arch@bytedance.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <86b0573753db20e40315c61f5d6e01bdc6a8313a.1765956025.git.zhengqi.arch@bytedance.com> X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: C57662000A X-Stat-Signature: c3ikmi1jfb538yyypwcn89jgax1g5ko7 X-Rspam-User: X-HE-Tag: 1766010218-563751 X-HE-Meta: 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 bYB/tELW 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 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 Wed, Dec 17, 2025 at 03:27:40PM +0800, Qi Zheng wrote: > From: Muchun Song > > In the near future, a folio will no longer pin its corresponding > memory cgroup. To ensure safety, it will only be appropriate to > hold the rcu read lock or acquire a reference to the memory cgroup > returned by folio_memcg(), thereby preventing it from being released. > > In the current patch, the rcu read lock is employed to safeguard > against the release of the memory cgroup in lru_gen_eviction(). > > This serves as a preparatory measure for the reparenting of the > LRU pages. > > Signed-off-by: Muchun Song > Signed-off-by: Qi Zheng > Reviewed-by: Harry Yoo Acked-by: Johannes Weiner