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,URIBL_BLOCKED, USER_AGENT_SANE_1 autolearn=unavailable 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 93A98C433DB for ; Thu, 4 Mar 2021 17:38:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 61B2564F5E for ; Thu, 4 Mar 2021 17:38:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239214AbhCDRh0 (ORCPT ); Thu, 4 Mar 2021 12:37:26 -0500 Received: from mga05.intel.com ([192.55.52.43]:57559 "EHLO mga05.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238054AbhCDRg5 (ORCPT ); Thu, 4 Mar 2021 12:36:57 -0500 IronPort-SDR: DQMZTf/3NzQ0v7inozieATYhcPcKracA1+KGVCOlg7Kqk5fVKH843sbeWtPnNbUYFIA6EjbaH3 TICA20xPJDdQ== X-IronPort-AV: E=McAfee;i="6000,8403,9913"; a="272469215" X-IronPort-AV: E=Sophos;i="5.81,222,1610438400"; d="scan'208";a="272469215" Received: from fmsmga004.fm.intel.com ([10.253.24.48]) by fmsmga105.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 04 Mar 2021 09:35:09 -0800 IronPort-SDR: VGpwhUK+Pw9QnSpgsePTNfYQokM/1Dqv2T8jcAvMiwHe9DTYl3Rw3rzhXDeQBmHgbbN0kyVpB9 xXxfI5W/fyMw== X-IronPort-AV: E=Sophos;i="5.81,222,1610438400"; d="scan'208";a="428734093" Received: from schen9-mobl.amr.corp.intel.com ([10.255.229.203]) by fmsmga004-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 04 Mar 2021 09:35:08 -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> From: Tim Chen Message-ID: <72cb8618-73af-ce08-d5d5-30cab30755a3@linux.intel.com> Date: Thu, 4 Mar 2021 09:35:08 -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 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. Thanks. Tim --- >From 412764d1fad219b04c77bcb1cc8161067c8424f2 Mon Sep 17 00:00:00 2001 From: Tim Chen Date: Tue, 2 Feb 2021 15:53:21 -0800 Subject: [PATCH v3] mm: Fix dropped memcg from mem cgroup soft limit tree To: Andrew Morton , Johannes Weiner , Michal Hocko ,Vladimir Davydov Cc: Dave Hansen , Ying Huang , linux-mm@kvack.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org During soft limit memory reclaim, we will temporarily remove the target mem cgroup from the cgroup soft limit tree. We then perform memory reclaim, update the memory usage excess count and re-insert the mem cgroup back into the mem cgroup soft limit tree according to the new memory usage excess count. However, when memory reclaim failed for a maximum number of attempts and we bail out of the reclaim loop, we forgot to put the target mem cgroup chosen for next reclaim back to the soft limit tree. This prevented pages in the mem cgroup from being reclaimed in the future even though the mem cgroup exceeded its soft limit. Fix the logic and put the mem cgroup back on the tree when page reclaim failed for the mem cgroup. Fixes: 4e41695356fb ("memory controller: soft limit reclaim on contention") --- mm/memcontrol.c | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index ed5cc78a8dbf..bc9cc73ff66b 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -3505,8 +3505,18 @@ 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) { + /* + * next_mz was removed in __mem_cgroup_largest_soft_limit_node. + * Put it back in tree with latest excess value. + */ + spin_lock_irq(&mctz->lock); + __mem_cgroup_remove_exceeded(next_mz, mctz); + excess = soft_limit_excess(next_mz->memcg); + __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