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Sat, 14 Nov 2026 11:56:35 -0800 (PST) Received: from [172.22.0.2] ([64.16.22.130]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-3b197d35525sm14940403a91.16.2026.11.14.11.56.33 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 14 Nov 2026 11:56:35 -0800 (PST) Date: Sat, 14 Nov 2026 11:56:30 -0800 From: Chris Down To: "Lorenzo Stoakes (ARM)" Cc: David Hildenbrand , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , David Rientjes , Shakeel Butt , Andrew Morton , Jann Horn , Pedro Falcato , "Matthew Wilcox (Oracle)" , Jan Kara , Nhat Pham , Johannes Weiner , Zi Yan , Matthew Brost , Joshua Hahn , Byungchul Park , Gregory Price , Ying Huang , Alistair Popple , Usama Arif , Kairui Song , Balbir Singh , =?utf-8?b?SsOpcsO0bWUgR2xpc3Nl?= , Kiryl Shutsemau , Yu-cheng Yu , Dave Hansen , Dennis Zhou , Tejun Heo , Christoph Lameter , Peng Fan , Josef Bacik , Chris Mason , linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, "Borislav Petkov (AMD)" , Mark Brown , "Dennis Zhou (Facebook)" , Rick Edgecombe , stable@vger.kernel.org Subject: Re: [PATCH v2 01/13] mm/mmap: free gathered pages before MMF_OOM_SKIP In-Reply-To: <20261113-mason-migrate-et-al-fixes-v2-1-50a2ed382b61@kernel.org> References: <20261113-mason-migrate-et-al-fixes-v2-0-50a2ed382b61@kernel.org> <20261113-mason-migrate-et-al-fixes-v2-1-50a2ed382b61@kernel.org> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Disposition: inline Message-ID: <20261114115630.0b75d0b49869d4fa@chrisdown.name> User-Agent: Mutt/2.4.3 (cc9e3943) (2026-10-09) Hi Lorenzo, Thanks! I've tested this with memcg OOMs where one kill is enough to get back under the limit, and with it the second kill is gone. It's probably worth knowing that for a memcg OOM this also needs my css_task_iter fix [1], which is in mm-hotfixes-unstable. Without it the memcg task scan stops seeing the victim once its last thread starts to exit, so oom_evaluate_task() never gets as far as checking MMF_OOM_SKIP for it. The test I used for this has a 48M memcg with a 30M task and a 1M task in it, and then a third task in there faults in 26M, so one kill should be enough. Out of 300 rounds of that, I got a second kill in 299 with neither patch, 277 with only this one, 147 with only that one, and none with both. [1] https://lore.kernel.org/r/avA1wXhTMs9eY2NF@chrisdown.name Reviewed-by: Chris Down Tested-by: Chris Down Chris