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Wed, 17 Dec 2025 14:34:50 -0800 (PST) Received: from localhost ([2603:7000:c01:2716:929a:4aff:fe16:c778]) by smtp.gmail.com with ESMTPSA id af79cd13be357-8beeb5f2974sm39870385a.19.2025.12.17.14.34.48 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 17 Dec 2025 14:34:49 -0800 (PST) Date: Wed, 17 Dec 2025 17:34:48 -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 21/28] mm: swap: prevent lruvec release in lru_gen_clear_refs() Message-ID: References: <42682f81686e31019504a6e025fa08d2c9dea718.1765956026.git.zhengqi.arch@bytedance.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <42682f81686e31019504a6e025fa08d2c9dea718.1765956026.git.zhengqi.arch@bytedance.com> X-Rspamd-Queue-Id: 023E2C0011 X-Stat-Signature: niyu5moijqrbrtrb84t77wcjqxpbqz74 X-Rspam-User: X-Rspamd-Server: rspam06 X-HE-Tag: 1766010890-759867 X-HE-Meta: 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 SrK5zDKY 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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 03:27:45PM +0800, Qi Zheng wrote: > From: Muchun Song > > In the near future, a folio will no longer pin its corresponding > memory cgroup. So an lruvec returned by folio_lruvec() could be > released without the rcu read lock or a reference to its memory > cgroup. > > In the current patch, the rcu read lock is employed to safeguard > against the release of the lruvec in lru_gen_clear_refs(). > > 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