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=-11.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,UNPARSEABLE_RELAY,URIBL_BLOCKED, USER_AGENT_SANE_1 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 CAC50C2D0A3 for ; Mon, 9 Nov 2020 07:57:04 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 3A0D620853 for ; Mon, 9 Nov 2020 07:57:02 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 3A0D620853 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.alibaba.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 7C8AF6B0036; Mon, 9 Nov 2020 02:57:01 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 779A16B005D; Mon, 9 Nov 2020 02:57:01 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 692DA6B0068; Mon, 9 Nov 2020 02:57:01 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0163.hostedemail.com [216.40.44.163]) by kanga.kvack.org (Postfix) with ESMTP id 3D6C06B0036 for ; Mon, 9 Nov 2020 02:57:01 -0500 (EST) Received: from smtpin05.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id D68151EE6 for ; Mon, 9 Nov 2020 07:57:00 +0000 (UTC) X-FDA: 77464123800.05.glove50_6210dd2272ea Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin05.hostedemail.com (Postfix) with ESMTP id BF338180199AC for ; Mon, 9 Nov 2020 07:57:00 +0000 (UTC) X-HE-Tag: glove50_6210dd2272ea X-Filterd-Recvd-Size: 4318 Received: from out30-43.freemail.mail.aliyun.com (out30-43.freemail.mail.aliyun.com [115.124.30.43]) by imf37.hostedemail.com (Postfix) with ESMTP for ; Mon, 9 Nov 2020 07:56:58 +0000 (UTC) X-Alimail-AntiSpam:AC=PASS;BC=-1|-1;BR=01201311R481e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e04426;MF=zhongjiang-ali@linux.alibaba.com;NM=1;PH=DS;RN=4;SR=0;TI=SMTPD_---0UEgPOPT_1604908613; Received: from L-X1DSLVDL-1420.local(mailfrom:zhongjiang-ali@linux.alibaba.com fp:SMTPD_---0UEgPOPT_1604908613) by smtp.aliyun-inc.com(127.0.0.1); Mon, 09 Nov 2020 15:56:53 +0800 Subject: Re: [PATCH] memcg, oom: check memcg margin for parallel oom From: zhong jiang To: hannes@cmpxchg.org, mhocko@kernel.org, akpm@linux-foundation.org Cc: linux-mm@kvack.org References: <1604652665-13640-1-git-send-email-zhongjiang-ali@linux.alibaba.com> Message-ID: <789efc6a-c71c-ef34-176f-2e4b0ce1eddf@linux.alibaba.com> Date: Mon, 9 Nov 2020 15:56:53 +0800 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.14; rv:83.0) Gecko/20100101 Thunderbird/83.0 MIME-Version: 1.0 In-Reply-To: <1604652665-13640-1-git-send-email-zhongjiang-ali@linux.alibaba.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: quoted-printable 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: I am sorry for my stupid email.=C2=A0=C2=A0 Please ignore it.=C2=A0 Thank= s=F0=9F=98=85 On 2020/11/6 4:51 =E4=B8=8B=E5=8D=88, zhongjiang-ali wrote: > From: Yafang Shao > > Memcg oom killer invocation is synchronized by the global oom_lock and > tasks are sleeping on the lock while somebody is selecting the victim o= r > potentially race with the oom_reaper is releasing the victim's memory. > This can result in a pointless oom killer invocation because a waiter > might be racing with the oom_reaper > > P1 oom_reaper P2 > oom_reap_task mutex_lock(oom_lock) > out_of_memory # no vic= tim because we have one already > __oom_reap_task_mm mute_unlock(oom_lock) > mutex_lock(oom_lock) > set MMF_OOM_SKIP > select_bad_process > # finds a new victim > > The page allocator prevents from this race by trying to allocate after = the > lock can be acquired (in __alloc_pages_may_oom) which acts as a last > minute check. Moreover page allocator simply doesn't block on the > oom_lock and simply retries the whole reclaim process. > > Memcg oom killer should do the last minute check as well. Call > mem_cgroup_margin to do that. Trylock on the oom_lock could be done as > well but this doesn't seem to be necessary at this stage. > > [mhocko@kernel.org: commit log] > > Suggested-by: Michal Hocko > Signed-off-by: Yafang Shao > Signed-off-by: Andrew Morton > Acked-by: Michal Hocko > Acked-by: Chris Down > Cc: Tetsuo Handa > Cc: David Rientjes > Cc: Johannes Weiner > Link: http://lkml.kernel.org/r/1594735034-19190-1-git-send-email-laoar.= shao@gmail.com > Signed-off-by: Linus Torvalds > Signed-off-by: zhongjiang-ali > --- > mm/memcontrol.c | 8 +++++++- > 1 file changed, 7 insertions(+), 1 deletion(-) > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > index b30a52d..369d9e1 100644 > --- a/mm/memcontrol.c > +++ b/mm/memcontrol.c > @@ -1663,15 +1663,21 @@ static bool mem_cgroup_out_of_memory(struct mem= _cgroup *memcg, gfp_t gfp_mask, > .gfp_mask =3D gfp_mask, > .order =3D order, > }; > - bool ret; > + bool ret =3D true; > =20 > if (mutex_lock_killable(&oom_lock)) > return true; > + > + if (mem_cgroup_margin(memcg) >=3D (1 << order)) > + goto unlock; > + > /* > * A few threads which were not waiting at mutex_lock_killable() can > * fail to bail out. Therefore, check again after holding oom_lock. > */ > ret =3D should_force_charge() || out_of_memory(&oc); > + > +unlock: > mutex_unlock(&oom_lock); > return ret; > }