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=-10.0 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 7DBCEC433E0 for ; Tue, 11 Aug 2020 13:56:31 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 2575B204FD for ; Tue, 11 Aug 2020 13:56:30 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2575B204FD Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 7AE8F6B0002; Tue, 11 Aug 2020 09:56:30 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 739988D0001; Tue, 11 Aug 2020 09:56:30 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 62A236B0006; Tue, 11 Aug 2020 09:56:30 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0002.hostedemail.com [216.40.44.2]) by kanga.kvack.org (Postfix) with ESMTP id 49E406B0002 for ; Tue, 11 Aug 2020 09:56:30 -0400 (EDT) Received: from smtpin18.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id D856C181AEF0B for ; Tue, 11 Aug 2020 13:56:29 +0000 (UTC) X-FDA: 77138437698.18.boot90_4d140bc26fe3 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin18.hostedemail.com (Postfix) with ESMTP id 8F3CF100EC665 for ; Tue, 11 Aug 2020 13:56:29 +0000 (UTC) X-HE-Tag: boot90_4d140bc26fe3 X-Filterd-Recvd-Size: 3248 Received: from mx2.suse.de (mx2.suse.de [195.135.220.15]) by imf49.hostedemail.com (Postfix) with ESMTP for ; Tue, 11 Aug 2020 13:56:29 +0000 (UTC) X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id BA8F6B0A5; Tue, 11 Aug 2020 13:56:48 +0000 (UTC) Date: Tue, 11 Aug 2020 15:56:26 +0200 From: Michal Hocko To: Alex Shi Cc: akpm@linux-foundation.org, Johannes Weiner , Vladimir Davydov , cgroups@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [Resend PATCH 2/6] mm/memcg: remove useless check on page->mem_cgroup Message-ID: <20200811135626.GL4793@dhcp22.suse.cz> References: <1597144232-11370-1-git-send-email-alex.shi@linux.alibaba.com> <1597144232-11370-2-git-send-email-alex.shi@linux.alibaba.com> <20200811113008.GK4793@dhcp22.suse.cz> <776b0e6f-4129-9fb9-0f66-47757cf320d5@linux.alibaba.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <776b0e6f-4129-9fb9-0f66-47757cf320d5@linux.alibaba.com> X-Rspamd-Queue-Id: 8F3CF100EC665 X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam04 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 Tue 11-08-20 20:54:18, Alex Shi wrote: > >From beeac61119ab39b1869c520c0f272fb8bab93765 Mon Sep 17 00:00:00 2001 > From: Alex Shi > Date: Wed, 5 Aug 2020 21:02:30 +0800 > Subject: [PATCH 2/6] memcg: bail out early from swap accounting when memcg is > disabled > > If we disabled memcg by cgroup_disable=memory, the swap charges are > still called. Let's return from the funcs earlier. They are not, are they? page->memcg will be NULL and so the charge is skipped and that will trigger a warning with your current ordering. Let me repeat again. Either you put it first in the series and argue that we can bail out early or keep the ordering then this makes sure the warning doesn't trigger. > Signed-off-by: Alex Shi > Reviewed-by: Roman Gushchin > Acked-by: Michal Hocko > Cc: Johannes Weiner > Cc: Michal Hocko > Cc: Vladimir Davydov > Cc: Andrew Morton > Cc: cgroups@vger.kernel.org > Cc: linux-mm@kvack.org > Cc: linux-kernel@vger.kernel.org > --- > mm/memcontrol.c | 6 ++++++ > 1 file changed, 6 insertions(+) > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > index 299382fc55a9..419cf565f40b 100644 > --- a/mm/memcontrol.c > +++ b/mm/memcontrol.c > @@ -7098,6 +7098,9 @@ void mem_cgroup_swapout(struct page *page, swp_entry_t entry) > VM_BUG_ON_PAGE(PageLRU(page), page); > VM_BUG_ON_PAGE(page_count(page), page); > > + if (mem_cgroup_disabled()) > + return; > + > if (cgroup_subsys_on_dfl(memory_cgrp_subsys)) > return; > > @@ -7163,6 +7166,9 @@ int mem_cgroup_try_charge_swap(struct page *page, swp_entry_t entry) > struct mem_cgroup *memcg; > unsigned short oldid; > > + if (mem_cgroup_disabled()) > + return 0; > + > if (!cgroup_subsys_on_dfl(memory_cgrp_subsys)) > return 0; > > -- > 1.8.3.1 -- Michal Hocko SUSE Labs