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[109.81.94.245]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-49c609c602dsm3640220f8f.46.2026.11.13.00.20.00 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 13 Nov 2026 00:20:00 -0800 (PST) Date: Fri, 13 Nov 2026 09:19:59 +0100 From: Michal Hocko To: Zhan Xusheng Cc: akpm@linux-foundation.org, hannes@cmpxchg.org, roman.gushchin@linux.dev, shakeel.butt@linux.dev, muchun.song@linux.dev, penguin-kernel@i-love.sakura.ne.jp, tj@kernel.org, mkoutny@suse.com, cgroups@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org, zhanxusheng@xiaomi.com Subject: Re: [PATCH] mm: memcontrol: don't miss processes whose leader has exited in OOM scans Message-ID: References: <20261102114029.1259655-1-zhanxusheng1024@gmail.com> X-Archived-By: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20261102114029.1259655-1-zhanxusheng1024@gmail.com> X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 866EB1C0004 X-Spam-Status: No, score=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_PASS,SPF_PASS autolearn=no autolearn_force=no version=4.0.1 X-Stat-Signature: uw7zgbdr3mcxkb5nncu64pfb57fu9kax X-Rspam-User: X-HE-Tag: 1794558003-971222 X-HE-Meta: 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 Sqw5Xq34 7rka/Qs/R2VGBXz5gkmbR952RiDFJfowCB/JfcDonK2Mgr2cnSg4rwb8jCFkjNprF15ZJX5SOjg6dP71PJR7RSKTUh0ek5V+xkCwyMsp0yyylgZxoGrj16jWJ+O7QZwDxyZM2zHCoTBXDmTGg6FoovPsa3CfAzT37dTqa+laxg0kq7f5mbkFzlcQTV5+fYsJH3lRs4Ff43tkS6xpcSp/WE6xhQ8Uc5AU3/UjewJ6Doldw9CiuVwQJZgCbsoM3AGJjXwtg/LptnkrEpL3fxHe0sKWFSWfZp89stMmH8CDz39XsjDqWZXJgZQ2L3UB9At44Yv3P/EIGl1U16wCFDkBX0tlmwd2ni+8c2EeauB1lSHicwmpdI8N2ikZoI5yv+/Bnu6QZ/eDbl7SVas7AwZ1wOd0yzQ== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 On Mon 02-11-26 19:40:29, Zhan Xusheng wrote: > Hi Michal, > > This is v1. v2 [1] reworked the check, but your questions apply to > both. > > On Mon, Nov 02, 2026 at 11:12:42AM +0100, Michal Hocko wrote: > > Is this a desirable/intended behavior? Shouldn't we move the dead leader > > along with the rest? > > Userspace sees it too. After writing the PID of such a process to > dst/cgroup.procs: > > src: cgroup.procs = 85 cgroup.threads = (empty) > dst: cgroup.procs = (empty) cgroup.threads = 86 87 > > Moving the leader would fix that, and memcg would then need no change, > as the PROCS walk already returns a dying leader with live threads. > The catch is that the leader has already gone through > cgroup_task_dead() and is still accounted by controllers: pids, for > one, uncharges it through task_css() when it is reaped, so the move > would also have to transfer its pids charge. Tejun, would that be > acceptable in the core? Do we have any conclusion on this? [...] > [1] https://lore.kernel.org/all/20261027144016.2582880-1-zhanxusheng1024@gmail.com/ > > Thanks, > Zhan Xusheng -- Michal Hocko SUSE Labs