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=-8.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,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 6E58CC433FF for ; Wed, 14 Aug 2019 11:33:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 43F39214DA for ; Wed, 14 Aug 2019 11:33:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1565782393; bh=nrOx7N8l+lMWtRLnzPLo+UJf0l2BDcnezae0I8VabLk=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=oeNN1hioDhoL/3YsbVWIbnh22Fl5iBRDoYKSu3lOs5Bd8CiOcGwO+MAMR+NsgpF3j uvVpy2F+X4xodKd7Z/JjtNjENBB9KfEHhWLoe2aUnK5Fkma2kD6FpIURbMYydWMv7C sxhvStMXNQQyySl9zi2+HqiVpo7LNFwMuThzeu0M= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727793AbfHNLdM (ORCPT ); Wed, 14 Aug 2019 07:33:12 -0400 Received: from mx2.suse.de ([195.135.220.15]:40466 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1727058AbfHNLdL (ORCPT ); Wed, 14 Aug 2019 07:33:11 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id A3579ADEF; Wed, 14 Aug 2019 11:33:10 +0000 (UTC) Date: Wed, 14 Aug 2019 13:33:10 +0200 From: Michal Hocko To: Roman Gushchin Cc: Andrew Morton , linux-mm@kvack.org, Johannes Weiner , linux-kernel@vger.kernel.org, kernel-team@fb.com Subject: Re: [PATCH] mm: memcontrol: flush percpu vmevents before releasing memcg Message-ID: <20190814113310.GW17933@dhcp22.suse.cz> References: <20190812233754.2570543-1-guro@fb.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190812233754.2570543-1-guro@fb.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon 12-08-19 16:37:54, Roman Gushchin wrote: > Similar to vmstats, percpu caching of local vmevents leads to an > accumulation of errors on non-leaf levels. This happens because > some leftovers may remain in percpu caches, so that they are > never propagated up by the cgroup tree and just disappear into > nonexistence with on releasing of the memory cgroup. > > To fix this issue let's accumulate and propagate percpu vmevents > values before releasing the memory cgroup similar to what we're > doing with vmstats. > > Since on cpu hotplug we do flush percpu vmstats anyway, we can > iterate only over online cpus. > > Fixes: 42a300353577 ("mm: memcontrol: fix recursive statistics correctness & scalabilty") > Signed-off-by: Roman Gushchin > Cc: Johannes Weiner Acked-by: Michal Hocko > --- > mm/memcontrol.c | 22 +++++++++++++++++++++- > 1 file changed, 21 insertions(+), 1 deletion(-) > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > index 6d2427abcc0c..249187907339 100644 > --- a/mm/memcontrol.c > +++ b/mm/memcontrol.c > @@ -3459,6 +3459,25 @@ static void memcg_flush_percpu_vmstats(struct mem_cgroup *memcg, bool slab_only) > } > } > > +static void memcg_flush_percpu_vmevents(struct mem_cgroup *memcg) > +{ > + unsigned long events[NR_VM_EVENT_ITEMS]; > + struct mem_cgroup *mi; > + int cpu, i; > + > + for (i = 0; i < NR_VM_EVENT_ITEMS; i++) > + events[i] = 0; > + > + for_each_online_cpu(cpu) > + for (i = 0; i < NR_VM_EVENT_ITEMS; i++) > + events[i] += raw_cpu_read( > + memcg->vmstats_percpu->events[i]); > + > + for (mi = memcg; mi; mi = parent_mem_cgroup(mi)) > + for (i = 0; i < NR_VM_EVENT_ITEMS; i++) > + atomic_long_add(events[i], &mi->vmevents[i]); > +} > + > static void memcg_offline_kmem(struct mem_cgroup *memcg) > { > struct cgroup_subsys_state *css; > @@ -4860,10 +4879,11 @@ static void __mem_cgroup_free(struct mem_cgroup *memcg) > int node; > > /* > - * Flush percpu vmstats to guarantee the value correctness > + * Flush percpu vmstats and vmevents to guarantee the value correctness > * on parent's and all ancestor levels. > */ > memcg_flush_percpu_vmstats(memcg, false); > + memcg_flush_percpu_vmevents(memcg); > for_each_node(node) > free_mem_cgroup_per_node_info(memcg, node); > free_percpu(memcg->vmstats_percpu); > -- > 2.21.0 -- Michal Hocko SUSE Labs