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Sun, 06 Apr 2025 14:34:11 -0700 (PDT) Received: from [2a00:79e0:2eb0:8:2005:ca9c:736:e1f6] ([2a00:79e0:2eb0:8:2005:ca9c:736:e1f6]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-229785c27b3sm68020535ad.97.2025.04.06.14.34.10 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 06 Apr 2025 14:34:10 -0700 (PDT) Date: Sun, 6 Apr 2025 14:34:09 -0700 (PDT) From: David Rientjes To: Michal Hocko cc: Andrew Morton , linux-mm@kvack.org, Rik van Riel , Johannes Weiner , Roman Gushchin , Shakeel Butt , Muchun Song , cgroups mailinglist , LKML , Michal Hocko Subject: Re: [PATCH] memcg, oom: do not bypass oom killer for dying tasks In-Reply-To: <20250402090117.130245-1-mhocko@kernel.org> Message-ID: References: <20250402090117.130245-1-mhocko@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII X-Rspam-User: X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: 4E525180005 X-Stat-Signature: qjgy8tujrd3nn7jpi77cqnjdzcyfrmyj X-HE-Tag: 1743975253-684241 X-HE-Meta: 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 6eN2ELZ2 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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 Wed, 2 Apr 2025, Michal Hocko wrote: > From: Michal Hocko > > 7775face2079 ("memcg: killed threads should not invoke memcg OOM killer") has added > a bypass of the oom killer path for dying threads because a very > specific workload (described in the changelog) could hit "no killable > tasks" path. This itself is not fatal condition but it could be annoying > if this was a common case. > > On the other hand the bypass has some issues on its own. Without > triggering oom killer we won't be able to trigger async oom reclaim > (oom_reaper) which can operate on killed tasks as well as long as they > still have their mm available. This could be the case during futex > cleanup when the memory as pointed out by Johannes in [1]. The said case > is still not fully understood but let's drop this bypass that was mostly > driven by an artificial workload and allow dying tasks to go into oom > path. This will make the code easier to reason about and also help > corner cases where oom_reaper could help to release memory. > > [1] https://lore.kernel.org/all/20241212183012.GB1026@cmpxchg.org/T/#u > > Suggested-by: Johannes Weiner > Signed-off-by: Michal Hocko Acked-by: David Rientjes