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a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1766049066; bh=m6maDrxugfkeNLKycZHBYmyqUqhUOYOT2Iqymt3Cj9U=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=OmNczh+k7Da92qoJ93NeWV1genL1oEJUEO12ITMlEoc1P+3ATqHCpBDJh2vKz4MYz JcrDdPzFzXoY5Hz3kj7oWEHWUO7d0VeOP8e/QcS58ouVcLE+0Xi1e2hK1ZqZMnsplR GwY0F/lrXnCBOuc5KdGOwPHXT+Yn8AAmbBWiZUd0OA7Y46stI+X4ZBaNKNTi31AFbB CtUc0ae39TdcjcQVz9aZnRy1nl/fOFnPOvfI0RFfaah2LgxnK5rR4zMDTa9tHhFAek IrxkC33jw4gIJnQ2uLNOSgrc3PUEjl+ut8o2x3KqAla6AlXhT6xVacsxzWj73LYMMf nzyJEqvkh6BYg== Message-ID: <2e153b06-e541-41de-9b5d-7869dc2aba72@kernel.org> Date: Thu, 18 Dec 2025 10:10:58 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 17/28] mm: thp: prevent memory cgroup release in folio_split_queue_lock{_irqsave}() To: Qi Zheng , hannes@cmpxchg.org, hughd@google.com, mhocko@suse.com, roman.gushchin@linux.dev, shakeel.butt@linux.dev, muchun.song@linux.dev, 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 Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, Qi Zheng References: <4cb81ea06298a3b41873b7086bfc68f64b2ba8be.1765956025.git.zhengqi.arch@bytedance.com> From: "David Hildenbrand (Red Hat)" Content-Language: en-US In-Reply-To: <4cb81ea06298a3b41873b7086bfc68f64b2ba8be.1765956025.git.zhengqi.arch@bytedance.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 7ED84100006 X-Stat-Signature: wu1a3q4nz4er1c665c8heskntdbo4uwr X-Rspam-User: X-HE-Tag: 1766049067-80435 X-HE-Meta: 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 l52ePWqS X8iD4oSGIefcClnbqAMUYy7aylk/mcKc51PPv0ksA8+d55u1a7+//m7DvALSzsfX6NPvuQkQ+ihEsj53r0CArkU3Izh20IR4mjiqenK9p+ORetMqetn8iTUTw8TtTiQlAk9HueHSIymsrv3EYszV3N7BxtOoAhZhzbXBfRo0nhan8q0R/URO3zP+KwqDThNtkYuP00HQltpAlM2xwedQ1Z8MrvWcBKRNcYNrE55VSVpbacviGsjT/nrZhP2RKxg3lNj/I4ryxCvLhBrxuTw1559KGj4hpzcRXsm7mgdTGU+YCVeZTGiYMHEBwjaQZ8PkOqCePLe2XqUVnzlWffdTNk1ncxbAU9fvdWpgJO/HZ9f/pCajAPTsMnB1f1UGat9GK7fURTOf9T0dC8VciTtj3wDtDsQ== 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 12/17/25 08:27, 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 folio_split_queue_lock{_irqsave}(). > > Signed-off-by: Qi Zheng > Reviewed-by: Harry Yoo > --- Acked-by: David Hildenbrand (Red Hat) -- Cheers David