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Wed, 13 Aug 2025 06:00:14 -0700 (PDT) Date: Wed, 13 Aug 2025 09:00:09 -0400 From: Johannes Weiner To: Kuniyuki Iwashima Cc: "David S. Miller" , Eric Dumazet , Jakub Kicinski , Neal Cardwell , Paolo Abeni , Willem de Bruijn , Matthieu Baerts , Mat Martineau , Michal Hocko , Roman Gushchin , Shakeel Butt , Andrew Morton , Michal =?iso-8859-1?Q?Koutn=FD?= , Tejun Heo , Simon Horman , Geliang Tang , Muchun Song , Mina Almasry , Kuniyuki Iwashima , netdev@vger.kernel.org, mptcp@lists.linux.dev, cgroups@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH v3 net-next 12/12] net-memcg: Decouple controlled memcg from global protocol memory accounting. Message-ID: <20250813130009.GA114408@cmpxchg.org> References: <20250812175848.512446-1-kuniyu@google.com> <20250812175848.512446-13-kuniyu@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250812175848.512446-13-kuniyu@google.com> X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: B31B114000C X-Stat-Signature: 1ukxag5dnefigmjbs3er7qckmdmjdr3q X-Rspam-User: X-HE-Tag: 1755090017-837887 X-HE-Meta: U2FsdGVkX18ahpcKLodHl7tLXhEwWlwZ7Lm/5eTPmXb3P1icHri68ukDvSQ55sI6zFsg/nAru8MaTxa+H+SCwy8s1qvb5DgxhMIxXhPATLBsEuwO3Fh9KR5Aw0XEQ1mYPJzQ1oUoPd60k97DaniG9qCQdm4CcCWTFh0+jtW5JgMaEPF4xx94wyd2+EopUKo6Wl03PTT19zE3r6jUzs6KoE9GnNcEW8q3SqGmVoCcx9Q3s5nTk1o+JipA3WlB2F5A5StNvgauAdvTl+qFVJJH36ppHEjeqXyYueLT/wd0qnvtT31UKFuf+rz293nisjBiMPRknI/TdtSgQoezei33lc3o1Hno4rgub9DqtN30yymUKBTuEXKpsHdr4kfpFIrhN4oFz5XqT5o3gcatZQqoQKzYIZUzllIIQFlz38ls82PC0nKM++LORTA/r0Ht6Rur8r7UNKVgTyHOFn4BMpDx3Z4ykprqq3P/gkYopNaFt8+34OoAxe49xjTwdTY1XKKFUNlRJEJe6gPLuLcLLSTJkpVdk35FVeq26P8bFtHF0DJQl60uPNEl8rtyVEdW6Y+a5S3Prpr4n8Rd67UBnJNVLbPUNT5V9DpCHjDEBqRfR8A2QBPsHvRlDcB+O1mR35o/D1lJA0JIrcOhSJqNMnLx4Jtpy8aoG4MVpSvD22WGfjrHHbqVTgIx1eXbmE/Bvg2wnWy3VWgFXbccXf4clojxxCm/6Wx4ir4fawGiWRVy2NLr+ZG1fxZZYVa01PrykG2OZiVfAl6IOrs2g5Ca0o1X9JhF0V0OOw+YOQiCUvr+x99H9/CRqBkdVXC9UZ/1GreaAWxgrFcSGDc+IWxlPFa+pPiJVtwqE/3atwYmYi8UiGmbTzzqe+gsJDbwSM5d3lP/hhljaA/hHh/stu/gXVbYx2EVzM7br8K4zy2UpRluA/1/pYnNxih4qKfvwyFmER+gaDgA+mkO4Q5JUv7mKPA FHXbpMLF 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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 Tue, Aug 12, 2025 at 05:58:30PM +0000, Kuniyuki Iwashima wrote: > If all workloads were guaranteed to be controlled under memcg, the issue > could be worked around by setting tcp_mem[0~2] to UINT_MAX. > > In reality, this assumption does not always hold, and processes that > belong to the root cgroup or opt out of memcg can consume memory up to > the global limit, becoming a noisy neighbour. As per the last thread, this is not a supported usecase. Opting out of memcg coverage for individual cgroups is a self-inflicted problem and misconfiguration. There is *no* memory isolation *at all* on such containers. Maybe their socket buffers is the only thing that happens to matter to *you*, but this is in no way a generic, universal, upstreamable solution. Knob or auto-detection is not the issue. Nacked-by: Johannes Weiner