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[195.135.220.15]) by mx.google.com with ESMTPS id y25si1341651edc.377.2019.07.03.00.06.41 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 03 Jul 2019 00:06:41 -0700 (PDT) Received-SPF: softfail (google.com: domain of transitioning mhocko@kernel.org does not designate 195.135.220.15 as permitted sender) client-ip=195.135.220.15; Authentication-Results: mx.google.com; spf=softfail (google.com: domain of transitioning mhocko@kernel.org does not designate 195.135.220.15 as permitted sender) smtp.mailfrom=mhocko@kernel.org; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=kernel.org X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 420BBB12E; Wed, 3 Jul 2019 07:06:41 +0000 (UTC) Date: Wed, 3 Jul 2019 09:06:32 +0200 From: Michal Hocko To: Tetsuo Handa Cc: Shakeel Butt , linux-mm@kvack.org Subject: Re: [PATCH] mm: mempolicy: don't select exited threads as OOM victims Message-ID: <20190703070632.GL978@dhcp22.suse.cz> References: <15099126-5d0f-51eb-7134-46c5c2db3bf0@i-love.sakura.ne.jp> <20190701131736.GX6376@dhcp22.suse.cz> <20190701134859.GZ6376@dhcp22.suse.cz> <20190701140434.GA6376@dhcp22.suse.cz> <20190701141647.GB6376@dhcp22.suse.cz> <0d81f46e-0b5f-0792-637f-fa88468f33cf@i-love.sakura.ne.jp> <20190702135148.GF978@dhcp22.suse.cz> <0c26d2d5-19b1-7915-e47e-60d86a946d09@i-love.sakura.ne.jp> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <0c26d2d5-19b1-7915-e47e-60d86a946d09@i-love.sakura.ne.jp> User-Agent: Mutt/1.10.1 (2018-07-13) 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: On Wed 03-07-19 06:26:55, Tetsuo Handa wrote: > On 2019/07/02 22:51, Michal Hocko wrote: > >>> I do not see any strong reason to keep the current ordering. OOM victim > >>> check is trivial so it shouldn't add a visible overhead for few > >>> unkillable tasks that we might encounter. > >>> > >> > >> Yes if we can tolerate that there can be only one OOM victim for !memcg OOM events > >> (because an OOM victim in a different OOM context will hit "goto abort;" path). > > > > You are right. Considering that we now have a guarantee of a forward > > progress then this should be tolerateable (a victim in a disjoint > > numaset will go away and other one can go ahead and trigger its own > > OOM). > > But it might take very long period before MMF_OOM_SKIP is set by the OOM reaper > or exit_mmap(). Until MMF_OOM_SKIP is set, OOM events from disjoint numaset can't > make forward progress. If that is a concern then I would stick with the current status quo until we see the issue to be reported by real workloads. -- Michal Hocko SUSE Labs