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=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT 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 83D26C433E0 for ; Wed, 10 Feb 2021 00:53:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3E3AD64E58 for ; Wed, 10 Feb 2021 00:53:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234470AbhBJAxd (ORCPT ); Tue, 9 Feb 2021 19:53:33 -0500 Received: from mga12.intel.com ([192.55.52.136]:10379 "EHLO mga12.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233872AbhBIWJC (ORCPT ); Tue, 9 Feb 2021 17:09:02 -0500 IronPort-SDR: MldrIrg3w5REvajKrIdpaITKdmkufNyApVrID8u1Z01K9GSP6RoUgjTYRj/fYzCvExQqdpj/lT ZDdG//SF87Iw== X-IronPort-AV: E=McAfee;i="6000,8403,9890"; a="161113148" X-IronPort-AV: E=Sophos;i="5.81,166,1610438400"; d="scan'208";a="161113148" Received: from orsmga006.jf.intel.com ([10.7.209.51]) by fmsmga106.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 09 Feb 2021 13:30:35 -0800 IronPort-SDR: 0NuyfNv3/5PMZnwwx7T68ohTVg5P571Vdttta2Ey1bZPdT00ExB3kdjlJBHEt+OpZP7kvgRGmH NYF2ky9Gr9Wg== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.81,166,1610438400"; d="scan'208";a="361953027" Received: from skl-02.jf.intel.com ([10.54.74.28]) by orsmga006.jf.intel.com with ESMTP; 09 Feb 2021 13:30:35 -0800 From: Tim Chen To: Andrew Morton , Johannes Weiner , Michal Hocko , Vladimir Davydov Cc: Tim Chen , Dave Hansen , Ying Huang , linux-mm@kvack.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH 2/3] mm: Force update of mem cgroup soft limit tree on usage excess Date: Tue, 9 Feb 2021 12:29:46 -0800 Message-Id: <90ef1dbc8ba6112794a3d09ecfed73f385f08eb7.1612902157.git.tim.c.chen@linux.intel.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org To rate limit updates to the mem cgroup soft limit tree, we only perform updates every SOFTLIMIT_EVENTS_TARGET (defined as 1024) memory events. However, this sampling based updates may miss a critical update: i.e. when the mem cgroup first exceeded its limit but it was not on the soft limit tree. It should be on the tree at that point so it could be subjected to soft limit page reclaim. If the mem cgroup had few memory events compared with other mem cgroups, we may not update it and place in on the mem cgroup soft limit tree for many memory events. And this mem cgroup excess usage could creep up and the mem cgroup could be hidden from the soft limit page reclaim for a long time. Fix this issue by forcing an update to the mem cgroup soft limit tree if a mem cgroup has exceeded its memory soft limit but it is not on the mem cgroup soft limit tree. Reviewed-by: Ying Huang Signed-off-by: Tim Chen --- mm/memcontrol.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index a51bf90732cb..d72449eeb85a 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -985,15 +985,22 @@ static bool mem_cgroup_event_ratelimit(struct mem_cgroup *memcg, */ static void memcg_check_events(struct mem_cgroup *memcg, struct page *page) { + struct mem_cgroup_per_node *mz; + bool force_update = false; + + mz = mem_cgroup_nodeinfo(memcg, page_to_nid(page)); + if (mz && !mz->on_tree && soft_limit_excess(mz->memcg) > 0) + force_update = true; + /* threshold event is triggered in finer grain than soft limit */ - if (unlikely(mem_cgroup_event_ratelimit(memcg, + if (unlikely((force_update) || mem_cgroup_event_ratelimit(memcg, MEM_CGROUP_TARGET_THRESH))) { bool do_softlimit; do_softlimit = mem_cgroup_event_ratelimit(memcg, MEM_CGROUP_TARGET_SOFTLIMIT); mem_cgroup_threshold(memcg); - if (unlikely(do_softlimit)) + if (unlikely((force_update) || do_softlimit)) mem_cgroup_update_tree(memcg, page); } } -- 2.20.1