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[209.85.220.65]) by mx.google.com with SMTPS id 206sor1751901ywi.61.2019.02.12.08.08.35 for (Google Transport Security); Tue, 12 Feb 2019 08:08:35 -0800 (PST) Received-SPF: pass (google.com: domain of hannes@cmpxchg.org designates 209.85.220.65 as permitted sender) client-ip=209.85.220.65; Authentication-Results: mx.google.com; dkim=pass header.i=@cmpxchg-org.20150623.gappssmtp.com header.s=20150623 header.b=tmPMzeR5; spf=pass (google.com: domain of hannes@cmpxchg.org designates 209.85.220.65 as permitted sender) smtp.mailfrom=hannes@cmpxchg.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=cmpxchg.org DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=cmpxchg-org.20150623.gappssmtp.com; s=20150623; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=25s6ZzpZBvcdHA9iUQ1peThatSnI2TBHe3HYkjmpXe0=; b=tmPMzeR5aNZd2v/KezfkXsfcEtRhX0m2PsZ9JjbgFgY4LQZw+t96OPzWv93Aofc0gd zGqfDwR3lKpwbqviQ5bLjsJlC5PcacEYfsxRcYXCt/J368b/xmGd/8jVT8TF54feRZv6 dB/qomR9zsAogwAaE/QaKxihmDPc9fyuoypeSfxz6Qb9reiSC0CZadM7o1a0Uy52Q4XE rXPQYgDv1OWEVDNDr3u2aisXLMEhZTYl0KNN9kp1ySgRyxZkDgl9hS9Gx+EWj4YqUCTK +uaiYapXarW8+FUqyqQdDbvbooF02ADtwASSBowC4E4ad1IcBngSDe71j/ncajjU38WO jD9A== X-Google-Smtp-Source: AHgI3Iar1Fw4cjlPFNp8NTALnE9GYU54kXPdqThc74HyaWjuSGDpvOQijVQSKBMX40Xk85wN8su1Lg== X-Received: by 2002:a81:1690:: with SMTP id 138mr684794yww.276.1549987714740; Tue, 12 Feb 2019 08:08:34 -0800 (PST) Received: from localhost ([2620:10d:c091:200::4:41f4]) by smtp.gmail.com with ESMTPSA id s7sm5004150ywe.20.2019.02.12.08.08.33 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Tue, 12 Feb 2019 08:08:33 -0800 (PST) Date: Tue, 12 Feb 2019 11:08:32 -0500 From: Johannes Weiner To: Michal Hocko Cc: Andrew Morton , Tetsuo Handa , David Rientjes , Linus Torvalds , Yong-Taek Lee , linux-mm@kvack.org, LKML , Michal Hocko Subject: Re: [PATCH] proc, oom: do not report alien mms when setting oom_score_adj Message-ID: <20190212160832.GB14231@cmpxchg.org> References: <20190212102129.26288-1-mhocko@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190212102129.26288-1-mhocko@kernel.org> User-Agent: Mutt/1.11.2 (2019-01-07) 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 Tue, Feb 12, 2019 at 11:21:29AM +0100, Michal Hocko wrote: > From: Michal Hocko > > Tetsuo has reported that creating a thousands of processes sharing MM > without SIGHAND (aka alien threads) and setting > /proc//oom_score_adj will swamp the kernel log and takes ages [1] > to finish. This is especially worrisome that all that printing is done > under RCU lock and this can potentially trigger RCU stall or softlockup > detector. > > The primary reason for the printk was to catch potential users who might > depend on the behavior prior to 44a70adec910 ("mm, oom_adj: make sure > processes sharing mm have same view of oom_score_adj") but after more > than 2 years without a single report I guess it is safe to simply remove > the printk altogether. > > The next step should be moving oom_score_adj over to the mm struct and > remove all the tasks crawling as suggested by [2] > > [1] http://lkml.kernel.org/r/97fce864-6f75-bca5-14bc-12c9f890e740@i-love.sakura.ne.jp > [2] http://lkml.kernel.org/r/20190117155159.GA4087@dhcp22.suse.cz > Reported-by: Tetsuo Handa > Signed-off-by: Michal Hocko Acked-by: Johannes Weiner