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=-11.5 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,UNPARSEABLE_RELAY,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 DBCABC433E0 for ; Wed, 12 Aug 2020 03:26:38 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 4CB04207F7 for ; Wed, 12 Aug 2020 03:26:38 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 4CB04207F7 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.alibaba.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 879668D0002; Tue, 11 Aug 2020 23:26:37 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 82A438D0001; Tue, 11 Aug 2020 23:26:37 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 719C28D0002; Tue, 11 Aug 2020 23:26:37 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0046.hostedemail.com [216.40.44.46]) by kanga.kvack.org (Postfix) with ESMTP id 585508D0001 for ; Tue, 11 Aug 2020 23:26:37 -0400 (EDT) Received: from smtpin11.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id CC6E152B0 for ; Wed, 12 Aug 2020 03:26:36 +0000 (UTC) X-FDA: 77140479192.11.scale83_110749626fe8 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin11.hostedemail.com (Postfix) with ESMTP id 9134C180F8B80 for ; Wed, 12 Aug 2020 03:26:36 +0000 (UTC) X-HE-Tag: scale83_110749626fe8 X-Filterd-Recvd-Size: 4512 Received: from out30-44.freemail.mail.aliyun.com (out30-44.freemail.mail.aliyun.com [115.124.30.44]) by imf41.hostedemail.com (Postfix) with ESMTP for ; Wed, 12 Aug 2020 03:26:35 +0000 (UTC) X-Alimail-AntiSpam:AC=PASS;BC=-1|-1;BR=01201311R381e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e01422;MF=alex.shi@linux.alibaba.com;NM=1;PH=DS;RN=7;SR=0;TI=SMTPD_---0U5Wk7Ug_1597202786; Received: from IT-FVFX43SYHV2H.local(mailfrom:alex.shi@linux.alibaba.com fp:SMTPD_---0U5Wk7Ug_1597202786) by smtp.aliyun-inc.com(127.0.0.1); Wed, 12 Aug 2020 11:26:27 +0800 Subject: Re: [Resend PATCH 2/6] mm/memcg: remove useless check on page->mem_cgroup To: Michal Hocko Cc: akpm@linux-foundation.org, Johannes Weiner , Vladimir Davydov , cgroups@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org 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> <20200811135626.GL4793@dhcp22.suse.cz> From: Alex Shi Message-ID: <0b5e1ac3-c9c7-35e9-2661-b58430314d0a@linux.alibaba.com> Date: Wed, 12 Aug 2020 11:25:53 +0800 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:68.0) Gecko/20100101 Thunderbird/68.7.0 MIME-Version: 1.0 In-Reply-To: <20200811135626.GL4793@dhcp22.suse.cz> Content-Type: text/plain; charset=gbk X-Rspamd-Queue-Id: 9134C180F8B80 X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam01 Content-Transfer-Encoding: quoted-printable 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: =D4=DA 2020/8/11 =CF=C2=CE=E79:56, Michal Hocko =D0=B4=B5=C0: > On Tue 11-08-20 20:54:18, Alex Shi wrote: >> >From beeac61119ab39b1869c520c0f272fb8bab93765 Mon Sep 17 00:00:00 200= 1 >> From: Alex Shi >> Date: Wed, 5 Aug 2020 21:02:30 +0800 >> Subject: [PATCH 2/6] memcg: bail out early from swap accounting when m= emcg is >> disabled>> >> If we disabled memcg by cgroup_disable=3Dmemory, 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. Hi Michal, Thanks for comment! Looks like we both agree the memcg wasn't charged, bu= t funcs just are called. :) =20 >=20 > 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 th= e > warning doesn't trigger. >=20 Is the following commit log fine? Thanks! Alex >From 999b0fe5fc65865c3b59ff28500d45572a4a9570 Mon Sep 17 00:00:00 2001 From: Alex Shi Date: Wed, 5 Aug 2020 21:02:30 +0800 Subject: [PATCH 2/6] mm/memcg: bail out early from swap accounting when m= emcg is disabled If we disabled memcg by cgroup_disable=3Dmemory, page->memcg will be NULL and so the charge is skipped and that will trigger a warning like below. Let's return from the funcs earlier. ---[ end trace f1f34bfc3b32ed2f ]--- anon flags:0x5005b48008000d(locked|uptodate|dirty|swapbacked) raw: 005005b48008000d dead000000000100 dead000000000122 ffff8897c7c76ad1 raw: 0000000000000022 0000000000000000 0000000200000000 0000000000000000 page dumped because: VM_WARN_ON_ONCE_PAGE(!memcg) 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_entr= y_t entry) VM_BUG_ON_PAGE(PageLRU(page), page); VM_BUG_ON_PAGE(page_count(page), page); =20 + if (mem_cgroup_disabled()) + return; + if (cgroup_subsys_on_dfl(memory_cgrp_subsys)) return; =20 @@ -7163,6 +7166,9 @@ int mem_cgroup_try_charge_swap(struct page *page, s= wp_entry_t entry) struct mem_cgroup *memcg; unsigned short oldid; =20 + if (mem_cgroup_disabled()) + return 0; + if (!cgroup_subsys_on_dfl(memory_cgrp_subsys)) return 0; =20 --=20 1.8.3.1