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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, 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-Migadu-Flow: FLOW_OUT X-Stat-Signature: 1k3zs189tg6jj6qwhckiqikksrpho9cb X-Rspam-User: X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 7052D140003 X-HE-Tag: 1766192829-921656 X-HE-Meta: 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 Y6ryyA01 LgeayZpDWsvkuM6o0xSbLzmn9gb7oiCNUp7RjwIgJOwZqzuEprHkMOCD7whAAzMr1qrz/LbFgo+lU7LJaMCwEgahQILK/LFm61Q5Akpr7mcbHss7jaUmTWDyOl2KWJXNm5ItMF8gbsc5iSwsdwu7qSzepvaQy0PJNb+DHaLdntjOf85eKLKr+XGVqE3VN2ya/MMo/rtaR5KZfwggqrqrD4Mw7Z8ocerw6/JtW92rRrv9FcD43kmbwe82cNk3cEufhxa2WGvVh8d6QC4sUxjiGehjHKZTDo7mytbImBfSzi4y1/n71JYHVGvXKJnLy/rUzk6h6Oh0mXyfADYg= 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: Shakeel Butt