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From: Shakeel Butt To: Qi Zheng Cc: hannes@cmpxchg.org, hughd@google.com, mhocko@suse.com, roman.gushchin@linux.dev, muchun.song@linux.dev, david@kernel.org, lorenzo.stoakes@oracle.com, ziy@nvidia.com, harry.yoo@oracle.com, yosry.ahmed@linux.dev, 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 v3 14/30] mm: mglru: prevent memory cgroup release in mglru Message-ID: References: <2a42effe148a31d308075f9fe72bd76d126b96b8.1768389889.git.zhengqi.arch@bytedance.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <2a42effe148a31d308075f9fe72bd76d126b96b8.1768389889.git.zhengqi.arch@bytedance.com> X-Migadu-Flow: FLOW_OUT X-Stat-Signature: s7774gmab1bgj4zc9xap8fofkfx9fruq X-Rspamd-Queue-Id: 2321040004 X-Rspam-User: X-Rspamd-Server: rspam02 X-HE-Tag: 1768690017-161668 X-HE-Meta: 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 BA0QYXES qmOS4iUJtNg94Icvdzw+7iqVk9E1X7gl3w+blpaUeEg/ukQjlxGLyGs4HZdAryBookAy4x3u4CQAGYPN33nHxolpoNuL8jSoH4WSkee8IWqo7EpNJZSZPGZ5YVYxbLX6hB5sHwbe5tlSoRswN1RMNuW6Tkr2uRa3wzrlH90PwEi65fb/X/6xQjpBcfZ+7zo7Agro4zaWTwagbO4koqVDuY/svS6KFkxqwNZD9CF8GrBsyU2ix2N3jkES35RSrpmhTfZbkQuCOmMDV7h78BVpE6fvUjXzLqr/hMDDg 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, Jan 14, 2026 at 07:32:41PM +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 mglru. > > This serves as a preparatory measure for the reparenting of the > LRU pages. > > Signed-off-by: Muchun Song > Signed-off-by: Qi Zheng Acked-by: Shakeel Butt