From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.5 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0B7BCC282C4 for ; Tue, 12 Feb 2019 16:08:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CE11A217D9 for ; Tue, 12 Feb 2019 16:08:37 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=cmpxchg-org.20150623.gappssmtp.com header.i=@cmpxchg-org.20150623.gappssmtp.com header.b="tmPMzeR5" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730897AbfBLQIg (ORCPT ); Tue, 12 Feb 2019 11:08:36 -0500 Received: from mail-yw1-f66.google.com ([209.85.161.66]:33760 "EHLO mail-yw1-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730438AbfBLQIg (ORCPT ); Tue, 12 Feb 2019 11:08:36 -0500 Received: by mail-yw1-f66.google.com with SMTP id p17so1216662ywg.0 for ; Tue, 12 Feb 2019 08:08:35 -0800 (PST) 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-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=25s6ZzpZBvcdHA9iUQ1peThatSnI2TBHe3HYkjmpXe0=; b=Fv3GnlpPlujHjaBO80E6tcUcilQqHIt335iRX20q7LILeLx/A7nQjZ2Z78xrzx8YQC JYx+3FGRcs3mX3ggmDJWybHR/qdSm43tOt7QQ3Vc/IOpviN/EcDJUNVG7rVd016DBIVT s4dWQ3t0vzdX3eg0e5tghIGFDRy0ximh+2ZfbLtsN2i2h71Hl+m562WvU7V7AMfgTb3F 724+kE/qB5KbHb7bo7E2R+8nusq8hUUCylIo4oljvU/HC8F8BKlQosS/8804+SLck272 oCUo3Mroo9tofB7xvhMNtTmRjUHt2UbrBpKXlCoURpjzyRoIrd1So1UnXF3CmtpCGKFU PPzg== X-Gm-Message-State: AHQUAuYGf70DunIK7PBNY3ZRLD8wIb4aEra6MPkLct9hJSNL3n4Eh5xZ V6f7T6+xOEGUsh/eSpjeWvfiDQ== 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) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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