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=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS 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 5BB4FC32789 for ; Tue, 6 Nov 2018 09:45:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 203B42085B for ; Tue, 6 Nov 2018 09:45:09 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 203B42085B Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=i-love.sakura.ne.jp Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387650AbeKFTJa (ORCPT ); Tue, 6 Nov 2018 14:09:30 -0500 Received: from www262.sakura.ne.jp ([202.181.97.72]:64869 "EHLO www262.sakura.ne.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2387484AbeKFTJa (ORCPT ); Tue, 6 Nov 2018 14:09:30 -0500 Received: from fsav103.sakura.ne.jp (fsav103.sakura.ne.jp [27.133.134.230]) by www262.sakura.ne.jp (8.15.2/8.15.2) with ESMTP id wA69iqnq012495; Tue, 6 Nov 2018 18:44:52 +0900 (JST) (envelope-from penguin-kernel@i-love.sakura.ne.jp) Received: from www262.sakura.ne.jp (202.181.97.72) by fsav103.sakura.ne.jp (F-Secure/fsigk_smtp/530/fsav103.sakura.ne.jp); Tue, 06 Nov 2018 18:44:52 +0900 (JST) X-Virus-Status: clean(F-Secure/fsigk_smtp/530/fsav103.sakura.ne.jp) Received: from [192.168.1.8] (softbank060157065137.bbtec.net [60.157.65.137]) (authenticated bits=0) by www262.sakura.ne.jp (8.15.2/8.15.2) with ESMTPSA id wA69ijWm012405 (version=TLSv1.2 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Tue, 6 Nov 2018 18:44:52 +0900 (JST) (envelope-from penguin-kernel@i-love.sakura.ne.jp) Subject: Re: [RFC PATCH 2/2] memcg: do not report racy no-eligible OOM tasks From: Tetsuo Handa To: Michal Hocko , Johannes Weiner Cc: linux-mm@kvack.org, David Rientjes , Andrew Morton , LKML References: <20181022071323.9550-1-mhocko@kernel.org> <20181022071323.9550-3-mhocko@kernel.org> <20181026142531.GA27370@cmpxchg.org> <20181026192551.GC18839@dhcp22.suse.cz> <20181026193304.GD18839@dhcp22.suse.cz> Message-ID: Date: Tue, 6 Nov 2018 18:44:43 +0900 User-Agent: Mozilla/5.0 (Windows NT 6.3; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org >From dc0d9ec3205a28680dcf2213c0ffe8820e8b5913 Mon Sep 17 00:00:00 2001 From: Tetsuo Handa Date: Tue, 6 Nov 2018 12:27:36 +0900 Subject: [PATCH] memcg: killed threads should not invoke memcg OOM killer It is possible that a single process group memcg easily swamps the log with no-eligible OOM victim messages after current thread was OOM-killed, due to race between the memcg charge and the OOM reaper [1]. Thread-1 Thread-2 OOM reaper try_charge() mem_cgroup_out_of_memory() mutex_lock(oom_lock) try_charge() mem_cgroup_out_of_memory() mutex_lock(oom_lock) out_of_memory() select_bad_process() oom_kill_process(current) wake_oom_reaper() oom_reap_task() # sets MMF_OOM_SKIP mutex_unlock(oom_lock) out_of_memory() select_bad_process() # no task mutex_unlock(oom_lock) We don't need to invoke the memcg OOM killer if current thread was killed when waiting for oom_lock, for mem_cgroup_oom_synchronize(true) and memory_max_write() can bail out upon SIGKILL, and try_charge() allows already killed/exiting threads to make forward progress. [1] https://lkml.kernel.org/r/ea637f9a-5dd0-f927-d26d-d0b4fd8ccb6f@i-love.sakura.ne.jp Signed-off-by: Tetsuo Handa --- mm/memcontrol.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 6e1469b..a97648a 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -1382,8 +1382,13 @@ static bool mem_cgroup_out_of_memory(struct mem_cgroup *memcg, gfp_t gfp_mask, }; bool ret; - mutex_lock(&oom_lock); - ret = out_of_memory(&oc); + if (mutex_lock_killable(&oom_lock)) + return true; + /* + * A few threads which were not waiting at mutex_lock_killable() can + * fail to bail out. Therefore, check again after holding oom_lock. + */ + ret = fatal_signal_pending(current) || out_of_memory(&oc); mutex_unlock(&oom_lock); return ret; } -- 1.8.3.1 From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-io1-f69.google.com (mail-io1-f69.google.com [209.85.166.69]) by kanga.kvack.org (Postfix) with ESMTP id 5D9A16B02F6 for ; Tue, 6 Nov 2018 04:45:06 -0500 (EST) Received: by mail-io1-f69.google.com with SMTP id k3-v6so13225900ioq.8 for ; Tue, 06 Nov 2018 01:45:06 -0800 (PST) Received: from www262.sakura.ne.jp (www262.sakura.ne.jp. [202.181.97.72]) by mx.google.com with ESMTPS id x5-v6si21621533ioa.43.2018.11.06.01.45.04 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 06 Nov 2018 01:45:04 -0800 (PST) Subject: Re: [RFC PATCH 2/2] memcg: do not report racy no-eligible OOM tasks From: Tetsuo Handa References: <20181022071323.9550-1-mhocko@kernel.org> <20181022071323.9550-3-mhocko@kernel.org> <20181026142531.GA27370@cmpxchg.org> <20181026192551.GC18839@dhcp22.suse.cz> <20181026193304.GD18839@dhcp22.suse.cz> Message-ID: Date: Tue, 6 Nov 2018 18:44:43 +0900 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Michal Hocko , Johannes Weiner Cc: linux-mm@kvack.org, David Rientjes , Andrew Morton , LKML