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From: Roman Gushchin To: Yue Zhao Cc: linux-mm@kvack.org, akpm@linux-foundation.org, hannes@cmpxchg.org, mhocko@kernel.org, shakeelb@google.com, muchun.song@linux.dev, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm: change memcg->oom_group access with atomic operations Message-ID: References: <20230220151638.1371-1-findns94@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230220151638.1371-1-findns94@gmail.com> X-Migadu-Flow: FLOW_OUT X-Rspamd-Queue-Id: C467440004 X-Rspamd-Server: rspam09 X-Rspam-User: X-Stat-Signature: ps9skekkyacq9c7o9fefgj36g1zwgti6 X-HE-Tag: 1676927391-262904 X-HE-Meta: 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 wy+hHZAb aMNEG8naVrybS0H/M1YJl/Ij8HrGPp9bXXB8pITHBc0kvgt1QA7F1VdyGz5a6ihkzJVBAF4TndBa4nvR/VCHy4+9m8fX1r6/rxLZbPYZYv7iljr7+eKCjh9BthDSJgtFY0c9dRx1u8NiD0/qEkBnobO6Vla4Ci/T6fq82 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: On Mon, Feb 20, 2023 at 11:16:38PM +0800, Yue Zhao wrote: > The knob for cgroup v2 memory controller: memory.oom.group > will be read and written simultaneously by user space > programs, thus we'd better change memcg->oom_group access > with atomic operations to avoid concurrency problems. > > Signed-off-by: Yue Zhao Hi Yue! I'm curious, have any seen any real issues which your patch is solving? Can you, please, provide a bit more details. Also, WRITE/READ_ONCE() don't generally make operations atomic, they only prevent the compiler from merging and re-fetching reads and writes. Thanks!