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=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=no 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 B6EADC433E0 for ; Fri, 7 Aug 2020 06:22:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8CEA222CAF for ; Fri, 7 Aug 2020 06:22:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1596781330; bh=8buI4U/A+YZMwTmUmzwOuFWCSMd7tVNO5fQy6sTm0yU=; h=Date:From:To:Subject:In-Reply-To:Reply-To:List-ID:From; b=ZGmpvdRuqUxHPzBZQTUnN9jGr1H3rVqh3lPunYKdRe8ECOALOPDfFTDw/nRJhRCzq 08dCpBsFRA82wAgYai2unqEMNcEN3onsfE3I340P85cOfsNeQfQhQg/oYNKh3DwcFc 0Cbm4Gct/3lwAQ2NluOkAB8cYvuSqElle6bpm32c= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726094AbgHGGWK (ORCPT ); Fri, 7 Aug 2020 02:22:10 -0400 Received: from mail.kernel.org ([198.145.29.99]:58556 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725845AbgHGGWK (ORCPT ); Fri, 7 Aug 2020 02:22:10 -0400 Received: from localhost.localdomain (c-73-231-172-41.hsd1.ca.comcast.net [73.231.172.41]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 5039F221E5; Fri, 7 Aug 2020 06:22:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1596781329; bh=8buI4U/A+YZMwTmUmzwOuFWCSMd7tVNO5fQy6sTm0yU=; h=Date:From:To:Subject:In-Reply-To:From; b=OD9SJB/p0NMRrUKp1k4SI+XY+ZSKnBu7FeMQfntAefLDV6E257gXhwXxcIMDBVfWI dpV1ALFh0J/1hSIw6k1yixYMyI0rb5j3EJ1I4EFwJgNQZ3YcBoffsIETg88i4l1UtV Ei/hoGbNuFh0u+z2Hb6WQqA670Fn6RVz1glNHhg8= Date: Thu, 06 Aug 2020 23:22:08 -0700 From: Andrew Morton To: akpm@linux-foundation.org, chris@chrisdown.name, hannes@cmpxchg.org, laoar.shao@gmail.com, linux-mm@kvack.org, mhocko@kernel.org, mhocko@suse.com, mm-commits@vger.kernel.org, penguin-kernel@i-love.sakura.ne.jp, rientjes@google.com, torvalds@linux-foundation.org Subject: [patch 090/163] memcg, oom: check memcg margin for parallel oom Message-ID: <20200807062208.OPynQN011%akpm@linux-foundation.org> In-Reply-To: <20200806231643.a2711a608dd0f18bff2caf2b@linux-foundation.org> User-Agent: s-nail v14.8.16 Sender: mm-commits-owner@vger.kernel.org Precedence: bulk Reply-To: linux-kernel@vger.kernel.org List-ID: X-Mailing-List: mm-commits@vger.kernel.org From: Yafang Shao Subject: memcg, oom: check memcg margin for parallel oom Memcg oom killer invocation is synchronized by the global oom_lock and tasks are sleeping on the lock while somebody is selecting the victim or 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 victim 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] Link: http://lkml.kernel.org/r/1594735034-19190-1-git-send-email-laoar.shao@gmail.com Suggested-by: Michal Hocko Signed-off-by: Yafang Shao Acked-by: Michal Hocko Acked-by: Chris Down Cc: Tetsuo Handa Cc: David Rientjes Cc: Johannes Weiner Signed-off-by: Andrew Morton --- mm/memcontrol.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) --- a/mm/memcontrol.c~memcg-oom-check-memcg-margin-for-parallel-oom +++ a/mm/memcontrol.c @@ -1663,15 +1663,21 @@ static bool mem_cgroup_out_of_memory(str .gfp_mask = gfp_mask, .order = order, }; - bool ret; + bool ret = true; if (mutex_lock_killable(&oom_lock)) return true; + + if (mem_cgroup_margin(memcg) >= (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 = should_force_charge() || out_of_memory(&oc); + +unlock: mutex_unlock(&oom_lock); return ret; } _