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Wed, 17 Dec 2025 14:33:12 -0800 (PST) Received: from localhost ([2603:7000:c01:2716:929a:4aff:fe16:c778]) by smtp.gmail.com with ESMTPSA id d75a77b69052e-4f35fcb439csm3688841cf.15.2025.12.17.14.33.11 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 17 Dec 2025 14:33:11 -0800 (PST) Date: Wed, 17 Dec 2025 17:33:11 -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 , Nhat Pham , Chengming Zhou , Qi Zheng Subject: Re: [PATCH v2 20/28] mm: zswap: prevent lruvec release in zswap_folio_swapin() Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 7B2C3180013 X-Stat-Signature: rru6q4ms9xd37uj9m395madqpoo7i4i5 X-Rspam-User: X-HE-Tag: 1766010793-330948 X-HE-Meta: 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 HNRNpkG8 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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 03:27:44PM +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 zswap_folio_swapin(). > > This serves as a preparatory measure for the reparenting of the > LRU pages. > > Signed-off-by: Muchun Song > Acked-by: Nhat Pham > Reviewed-by: Chengming Zhou > Signed-off-by: Qi Zheng > Reviewed-by: Harry Yoo Acked-by: Johannes Weiner Btw, it would make the series shorter if you combined the changes to workingset.c, zswap.c etc. It should still be easy to review as long as you just stick to making folio_memcg(), folio_lruvec() calls safe.