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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, Qi Zheng Subject: Re: [PATCH v2 18/28] mm: zswap: prevent memory cgroup release in zswap_compress() Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Migadu-Flow: FLOW_OUT X-Rspam-User: X-Rspamd-Queue-Id: 7367C120006 X-Rspamd-Server: rspam10 X-Stat-Signature: 1zmnz4t5ode6ukk5r8y3eoa8rx67qrpp X-HE-Tag: 1766193260-425732 X-HE-Meta: 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 nUoj0j4R iP4img4pPTMU9csC6z+HwxDk2L0Ijl1fdjH0Jj4Pw1on2YjAZJZavaN32TTM3x1FWYXr8lypHXCbWHBjiiChbfzsaeuvH8SpU8VtUgBU3uH135ggNsnaQ0d5zuOKwo+Kzpyjo+XEb9BvpJVRaRCiM4Y2HUp7WmUurvmWDX/uUsM5nrTXDqIBJQAYBe+IsgnBNgx+DlEROpei4nvK5L5jnWZOTQko7ZtCVi/1qoVHX+032KEV8CP+xFhRshmeA7BNogfRN0mZfTbG/mWB/fZ5TeoXCG38sjYp7v6vZ943/sDGp91dYhgm09TwRDQipHm9led0l/fvJA5Wqj7PY2EFqoq0EqA== 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 03:27:42PM +0800, Qi Zheng wrote: > From: Qi Zheng > > 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 zswap_compress(). > > Signed-off-by: Qi Zheng Acked-by: Shakeel Butt