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=-15.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,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 A0580C433DB for ; Fri, 5 Mar 2021 19:08:09 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 2D4FF6509A for ; Fri, 5 Mar 2021 19:08:09 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2D4FF6509A Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.intel.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id B0B876B005D; Fri, 5 Mar 2021 14:08:08 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id A93AC6B006C; Fri, 5 Mar 2021 14:08:08 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 935D46B006E; Fri, 5 Mar 2021 14:08:08 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0046.hostedemail.com [216.40.44.46]) by kanga.kvack.org (Postfix) with ESMTP id 77F906B005D for ; Fri, 5 Mar 2021 14:08:08 -0500 (EST) Received: from smtpin14.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id 3886E180ACC44 for ; Fri, 5 Mar 2021 19:08:08 +0000 (UTC) X-FDA: 77886755856.14.D221352 Received: from mga05.intel.com (mga05.intel.com [192.55.52.43]) by imf09.hostedemail.com (Postfix) with ESMTP id 17A37600010E for ; Fri, 5 Mar 2021 19:08:05 +0000 (UTC) IronPort-SDR: 0H3VxMjcEqS1PFBFghjwErh/GnTIi2oTpL4RI0pNRqZuZplXQkBPVRi2zdqdewin5cdj1g8HwX YEiwjiRdq+Rw== X-IronPort-AV: E=McAfee;i="6000,8403,9914"; a="272722207" X-IronPort-AV: E=Sophos;i="5.81,226,1610438400"; d="scan'208";a="272722207" Received: from orsmga003.jf.intel.com ([10.7.209.27]) by fmsmga105.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 05 Mar 2021 11:08:00 -0800 IronPort-SDR: hHPr2NOdMM3kwVF0lCWTAa3OSE3EVPljoLuM7c8D8zhnq6pEaijfvn/l6lZ9dBLkVNRvJayJj6 T/ZhnlnY+VaA== X-IronPort-AV: E=Sophos;i="5.81,226,1610438400"; d="scan'208";a="368694013" Received: from schen9-mobl.amr.corp.intel.com ([10.251.16.203]) by orsmga003-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 05 Mar 2021 11:08:00 -0800 Subject: Re: [PATCH v2 1/3] mm: Fix dropped memcg from mem cgroup soft limit tree To: Michal Hocko Cc: Andrew Morton , Johannes Weiner , Vladimir Davydov , Dave Hansen , Ying Huang , linux-mm@kvack.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org References: <8d35206601ccf0e1fe021d24405b2a0c2f4e052f.1613584277.git.tim.c.chen@linux.intel.com> <72cb8618-73af-ce08-d5d5-30cab30755a3@linux.intel.com> From: Tim Chen Message-ID: <087bed0e-5b5f-0e25-c247-7fcb34de1513@linux.intel.com> Date: Fri, 5 Mar 2021 11:07:59 -0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.6.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Stat-Signature: jgnpcxnzjzfcw1bhd9i9tonpycn8t3yt X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 17A37600010E Received-SPF: none (linux.intel.com>: No applicable sender policy available) receiver=imf09; identity=mailfrom; envelope-from=""; helo=mga05.intel.com; client-ip=192.55.52.43 X-HE-DKIM-Result: none/none X-HE-Tag: 1614971285-290387 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: On 3/5/21 1:11 AM, Michal Hocko wrote: > On Thu 04-03-21 09:35:08, Tim Chen wrote: >> >> >> On 2/18/21 11:13 AM, Michal Hocko wrote: >> >>> >>> Fixes: 4e41695356fb ("memory controller: soft limit reclaim on contention") >>> Acked-by: Michal Hocko >>> >>> Thanks! >>>> --- >>>> mm/memcontrol.c | 6 +++++- >>>> 1 file changed, 5 insertions(+), 1 deletion(-) >>>> >>>> diff --git a/mm/memcontrol.c b/mm/memcontrol.c >>>> index ed5cc78a8dbf..a51bf90732cb 100644 >>>> --- a/mm/memcontrol.c >>>> +++ b/mm/memcontrol.c >>>> @@ -3505,8 +3505,12 @@ unsigned long mem_cgroup_soft_limit_reclaim(pg_data_t *pgdat, int order, >>>> loop > MEM_CGROUP_MAX_SOFT_LIMIT_RECLAIM_LOOPS)) >>>> break; >>>> } while (!nr_reclaimed); >>>> - if (next_mz) >>>> + if (next_mz) { >>>> + spin_lock_irq(&mctz->lock); >>>> + __mem_cgroup_insert_exceeded(next_mz, mctz, excess); >>>> + spin_unlock_irq(&mctz->lock); >>>> css_put(&next_mz->memcg->css); >>>> + } >>>> return nr_reclaimed; >>>> } >>>> >>>> -- >>>> 2.20.1 >>> >> >> Mel, >> >> Reviewing this patch a bit more, I realize that there is a chance that the removed >> next_mz could be inserted back to the tree from a memcg_check_events >> that happen in between. So we need to make sure that the next_mz >> is indeed off the tree and update the excess value before adding it >> back. Update the patch to the patch below. > > This scenario is certainly possible but it shouldn't really matter much > as __mem_cgroup_insert_exceeded bails out when the node is on the tree > already. > Makes sense. We should still update the excess value with + excess = soft_limit_excess(next_mz->memcg); + __mem_cgroup_insert_exceeded(next_mz, mctz, excess); before doing insertion. The excess value was recorded from previous mz in the loop and needs to be updated to that of next_mz. Tim