From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1426224AbcBRMIx (ORCPT ); Thu, 18 Feb 2016 07:08:53 -0500 Received: from mail-wm0-f54.google.com ([74.125.82.54]:33566 "EHLO mail-wm0-f54.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1425369AbcBRMIv (ORCPT ); Thu, 18 Feb 2016 07:08:51 -0500 Date: Thu, 18 Feb 2016 13:08:49 +0100 From: Michal Hocko To: Tetsuo Handa Cc: rientjes@google.com, akpm@linux-foundation.org, 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 Subject: Re: [PATCH v2] mm,oom: exclude oom_task_origin processes if they are OOM-unkillable. Message-ID: <20160218120849.GC18149@dhcp22.suse.cz> References: <1455719460-7690-1-git-send-email-penguin-kernel@I-love.SAKURA.ne.jp> <20160218080909.GA18149@dhcp22.suse.cz> <201602181930.HIH09321.SFVFOQLHOFMJOt@I-love.SAKURA.ne.jp> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <201602181930.HIH09321.SFVFOQLHOFMJOt@I-love.SAKURA.ne.jp> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu 18-02-16 19:30:12, Tetsuo Handa wrote: [...] > Commit 9cbb78bb314360a8 changed oom_scan_process_thread() to > always pass memcg == NULL by removing memcg argument from > oom_scan_process_thread(). As a result, after that commit, > we are doing test_tsk_thread_flag(p, TIF_MEMDIE) check and > oom_task_origin(p) check between two oom_unkillable_task() > calls of memcg OOM case. Why don't we skip these checks by > passing memcg != NULL to first oom_unkillable_task() call? > Was this change by error? I am not really sure I understand your question. The point is that mem_cgroup_out_of_memory does for_each_mem_cgroup_tree which means that only tasks from the given memcg hierarchy is checked and oom_unkillable_task cares about memcg only for /* When mem_cgroup_out_of_memory() and p is not member of the group */ if (memcg && !task_in_mem_cgroup(p, memcg)) return true; which is never true by definition. I guess we can safely remove the memcg argument from oom_badness and oom_unkillable_task. At least from a quick glance... -- Michal Hocko SUSE Labs