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=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 AF864C433B4 for ; Wed, 14 Apr 2021 09:20:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8F8DA613CD for ; Wed, 14 Apr 2021 09:20:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1347617AbhDNJVE (ORCPT ); Wed, 14 Apr 2021 05:21:04 -0400 Received: from mx2.suse.de ([195.135.220.15]:60074 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230247AbhDNJUs (ORCPT ); Wed, 14 Apr 2021 05:20:48 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1618392025; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=Mr3scI/YTtt7ex3orLLYYw+pW4lHQUrTP1/LVJpZfoM=; b=odp2cs3oBeu4/nv5hFcVVVM+v8y5f7n9+IxPU37m5dVSeAFfRwLsTVeuh12rWg3yWR4hFy uWPRvHKtgnQvNur1pwxkK7GOdz4WpdFSd49qg7j4J4TSjwLq2jN7htiwSQCrk8ajYQ3p1/ DEByuGHjeF8BnVGL0mHfPhKVuIbtc0w= Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id D0940AE37; Wed, 14 Apr 2021 09:20:24 +0000 (UTC) Date: Wed, 14 Apr 2021 11:20:24 +0200 From: Michal Hocko To: Muchun Song Cc: guro@fb.com, hannes@cmpxchg.org, akpm@linux-foundation.org, shakeelb@google.com, vdavydov.dev@gmail.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, duanxiongchun@bytedance.com, fam.zheng@bytedance.com Subject: Re: [PATCH 1/7] mm: memcontrol: fix page charging in page replacement Message-ID: References: <20210413065153.63431-1-songmuchun@bytedance.com> <20210413065153.63431-2-songmuchun@bytedance.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210413065153.63431-2-songmuchun@bytedance.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue 13-04-21 14:51:47, Muchun Song wrote: > The pages aren't accounted at the root level, so do not charge the page > to the root memcg in page replacement. Although we do not display the > value (mem_cgroup_usage) so there shouldn't be any actual problem, but > there is a WARN_ON_ONCE in the page_counter_cancel(). Who knows if it > will trigger? So it is better to fix it. > > Signed-off-by: Muchun Song > Acked-by: Johannes Weiner > Reviewed-by: Shakeel Butt Acked-by: Michal Hocko > --- > mm/memcontrol.c | 8 +++++--- > 1 file changed, 5 insertions(+), 3 deletions(-) > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > index 64ada9e650a5..f229de925aa5 100644 > --- a/mm/memcontrol.c > +++ b/mm/memcontrol.c > @@ -6806,9 +6806,11 @@ void mem_cgroup_migrate(struct page *oldpage, struct page *newpage) > /* Force-charge the new page. The old one will be freed soon */ > nr_pages = thp_nr_pages(newpage); > > - page_counter_charge(&memcg->memory, nr_pages); > - if (do_memsw_account()) > - page_counter_charge(&memcg->memsw, nr_pages); > + if (!mem_cgroup_is_root(memcg)) { > + page_counter_charge(&memcg->memory, nr_pages); > + if (do_memsw_account()) > + page_counter_charge(&memcg->memsw, nr_pages); > + } > > css_get(&memcg->css); > commit_charge(newpage, memcg); > -- > 2.11.0 -- Michal Hocko SUSE Labs