From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-io0-f172.google.com (mail-io0-f172.google.com [209.85.223.172]) by kanga.kvack.org (Postfix) with ESMTP id C7F546B0253 for ; Wed, 17 Feb 2016 08:07:46 -0500 (EST) Received: by mail-io0-f172.google.com with SMTP id l127so35537881iof.3 for ; Wed, 17 Feb 2016 05:07:46 -0800 (PST) Received: from www262.sakura.ne.jp (www262.sakura.ne.jp. [2001:e42:101:1:202:181:97:72]) by mx.google.com with ESMTPS id h80si4925686ioh.83.2016.02.17.05.07.45 for (version=TLS1 cipher=AES128-SHA bits=128/128); Wed, 17 Feb 2016 05:07:46 -0800 (PST) Subject: Re: [PATCH 2/6] mm,oom: don't abort on exiting processes when selecting a victim. From: Tetsuo Handa References: <201602171928.GDE00540.SLJMOFFQOHtFVO@I-love.SAKURA.ne.jp> <201602171930.AII18204.FMOSVFQFOJtLOH@I-love.SAKURA.ne.jp> <20160217125418.GF29196@dhcp22.suse.cz> In-Reply-To: <20160217125418.GF29196@dhcp22.suse.cz> Message-Id: <201602172207.GAG52105.FOtMJOFQOVSFHL@I-love.SAKURA.ne.jp> Date: Wed, 17 Feb 2016 22:07:31 +0900 Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: owner-linux-mm@kvack.org List-ID: To: mhocko@kernel.org Cc: akpm@linux-foundation.org, rientjes@google.com, mgorman@suse.de, oleg@redhat.com, torvalds@linux-foundation.org, hughd@google.com, andrea@kernel.org, riel@redhat.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Michal Hocko wrote: > On Wed 17-02-16 19:30:41, Tetsuo Handa wrote: > > >From 22bd036766e70f0df38c38f3ecc226e857d20faf Mon Sep 17 00:00:00 2001 > > From: Tetsuo Handa > > Date: Wed, 17 Feb 2016 16:30:59 +0900 > > Subject: [PATCH 2/6] mm,oom: don't abort on exiting processes when selecting a victim. > > > > Currently, oom_scan_process_thread() returns OOM_SCAN_ABORT when there > > is a thread which is exiting. But it is possible that that thread is > > blocked at down_read(&mm->mmap_sem) in exit_mm() called from do_exit() > > whereas one of threads sharing that memory is doing a GFP_KERNEL > > allocation between down_write(&mm->mmap_sem) and up_write(&mm->mmap_sem) > > (e.g. mmap()). Under such situation, the OOM killer does not choose a > > victim, which results in silent OOM livelock problem. > > Again, such a thread/task will have fatal_signal_pending and so have > access to memory reserves. So the text is slightly misleading imho. > Sure if the memory reserves are depleted then we will not move on but > then it is not clear whether the current patch helps either. I don't think so. Please see http://lkml.kernel.org/r/201602151958.HCJ48972.FFOFOLMHSQVJtO@I-love.SAKURA.ne.jp . There is a race window before such a thread/task receives SIGKILL. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org