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[109.81.83.7]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-47fb6b18a9fsm5229420f8f.32.2026.07.29.01.02.23 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 29 Jul 2026 01:02:23 -0700 (PDT) Date: Wed, 29 Jul 2026 10:02:22 +0200 From: Michal Hocko To: Guopeng Zhang Cc: Johannes Weiner , Roman Gushchin , Shakeel Butt , Andrew Morton , Muchun Song , cgroups@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Guopeng Zhang Subject: Re: [PATCH] mm: memcg: stop reclaim when a limit update is superseded Message-ID: References: <20260724021805.1234583-1-guopeng.zhang@linux.dev> <615d091c-bd3b-4686-817e-5b29756542ff@linux.dev> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 19C0140010 X-Rspam-User: X-Stat-Signature: cx6esi8mgtwcazek4ge6tbk787jpmu4j X-HE-Tag: 1785312145-434943 X-HE-Meta: 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 v6pDTaOy 8ATrem9G1FAhIdBG30Cds96tTLCErkKw6OrCwvgWWj1RBE9V7uDvHAWpPFfs3FbBOjkw2+BXqfYsQc7a7hjfziRVQrYGzmu1j9r+Ia8cP2frIs10m5KNSDVzEN1q3aMalzeJQwmNVmjB/b1QpadasmwI6waNZdM7HJZCUgoexMOl6lcXgxrWUYtiXczeTHvUErIL1ONkexhU+YaLKxEA+6NJSSVfMl869Unf61ALOatYuNHo+Hdiz68JaTyIVaxGf/jnx8o0ZRGGu3Nb+2UTHUDQdSAC4tr6im7+QPqz8vzfQZSl3Ilv+UBK393Lv088k/BGaGS012t902eAK/KejcfC57GRRoaNImL2VfVmzEYR4iQYiOd9dtHHEt+6y2BokYf7ivNZtceX0FZMZaVEuSS5/Y0uXAWby2UbWXjY8hx8XCU0N5sW64ytMSOoKG/xTIqezFYPQsMSy8jVcBUItWzR5OQ== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Wed 29-07-26 14:15:25, Guopeng Zhang wrote: > > > 在 2026/7/27 21:58, Michal Hocko 写道: > > On Mon 27-07-26 20:59:23, Guopeng Zhang wrote: > >> > >> > >> 在 2026/7/27 16:16, Michal Hocko 写道: > >>> On Fri 24-07-26 10:18:05, Guopeng Zhang wrote: [...] > > Is this trying to replicate any real workload? One would expect that > > writers to limit do some sort of coordination otherwise the exact > > behavior is not really well defined. > > > > No, this was not motivated by a reported production workload. We found > it through automated randomized testing for our cgroup observability > work and reduced it to the reproducer above. This is an important detail to be mentioned in the changelog. Describing motivation for a change is really important, especially if it has direct impact in user interface behavior. -- Michal Hocko SUSE Labs