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=-8.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, MAILING_LIST_MULTI,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 9DA39C433DB for ; Wed, 24 Mar 2021 08:51:23 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id EB470601FC for ; Wed, 24 Mar 2021 08:51:22 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org EB470601FC Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=bytedance.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 326C36B029F; Wed, 24 Mar 2021 04:51:22 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 2D6E16B02A0; Wed, 24 Mar 2021 04:51:22 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 1C8EA6B02A2; Wed, 24 Mar 2021 04:51:22 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0146.hostedemail.com [216.40.44.146]) by kanga.kvack.org (Postfix) with ESMTP id 027686B029F for ; Wed, 24 Mar 2021 04:51:21 -0400 (EDT) Received: from smtpin14.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id B661218150C26 for ; Wed, 24 Mar 2021 08:51:21 +0000 (UTC) X-FDA: 77954148762.14.F53E09A Received: from mail-pg1-f170.google.com (mail-pg1-f170.google.com [209.85.215.170]) by imf10.hostedemail.com (Postfix) with ESMTP id E9C1A407F8DC for ; Wed, 24 Mar 2021 08:51:18 +0000 (UTC) Received: by mail-pg1-f170.google.com with SMTP id v2so14165740pgk.11 for ; Wed, 24 Mar 2021 01:51:19 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bytedance-com.20150623.gappssmtp.com; s=20150623; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=D9t8jH7fiBRNuIpJOprUlwIjQmokxDINeAIuoJ7WsEI=; b=j4H4/cvDRqgHQCNnDg0HwFrPYKAgXoJpgGRMWG8HjKYfH926TB4MRWEiuxCaU1K2Kb woUMNc9qO1qA7/XZH3VEEe2c0RMiYPNrvko7Fy0wKNFcuJtHHw5JAqTXmxcvV+XfEQar vsNs/mdSoKBRN1/3Hxt1zsDwWQ44SvkYxnWpwvtVAsZnah/xDjpzyZQ5helZfwWF4Kqc 9vy+GYvo8+FqDq42I6jsxh68pObJO2xf2nt1x1VDJJ7ZDAlEZqzeqjNKTtK1Ie5duYhi Zvn9aPcU1ftOGBOsWNbBp/H3V/eXbrRQDOoBSb9j83hxucYZUvdgkV9pWB7cgYwlW4jb zqug== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=D9t8jH7fiBRNuIpJOprUlwIjQmokxDINeAIuoJ7WsEI=; b=RnV3HV07lI+yFhrsXUUAFveIYM8/Y80DkSWQCKsRCxpLnpzw8L9AZakl5KEhjt+8TD HzDgfgrFP+gEIk3pKJtmDDwGXpUwZzw0qDz9JSl9SYLRkq9D7wqxk7UWU+rF/sCh0ilr NMNOobZcUdZ47N9uSHwfVhVKgBtu57TSU2dwCjuBBZALVxzhwYLkALdc3HqEcorurapz rWjWKrsHi46dm6mQ/j7V++e4iKdsWvnr0BhwImHzlZUGuNrsM7tg1frJaxT3aq46zUia dHTu+zhBes7OVfcuHfFkKfx1qxQK9KYXZxfnZOK7L4WTouuPyLTAxTIm3BE5h0eKz1wH uhug== X-Gm-Message-State: AOAM531uxKR86K3eQVDQCdrJiQfUejl0i5mLsGtun7E4Hjp/p9MZbbN/ ONs0U9tWAalaUrI1oE6Qehguwi0gHHUFgYl9vsrRqg== X-Google-Smtp-Source: ABdhPJwX6oaoOONDaii/WKm7gZdPV1gXoOejYkts/sZ0DJFoA4ZGka5pHxdEPlnr77OXIP71hN4AHiGETMo69iqt5h4= X-Received: by 2002:aa7:9e5b:0:b029:1f1:5ba4:57a2 with SMTP id z27-20020aa79e5b0000b02901f15ba457a2mr2195394pfq.59.1616575878821; Wed, 24 Mar 2021 01:51:18 -0700 (PDT) MIME-Version: 1.0 References: <20210323145653.25684-1-songmuchun@bytedance.com> In-Reply-To: From: Muchun Song Date: Wed, 24 Mar 2021 16:50:41 +0800 Message-ID: Subject: Re: [External] Re: [PATCH] mm: memcontrol: fix memsw uncharge for root_mem_cgroup To: Michal Hocko Cc: Roman Gushchin , Johannes Weiner , Andrew Morton , Shakeel Butt , Vladimir Davydov , LKML , Linux Memory Management List Content-Type: text/plain; charset="UTF-8" X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: E9C1A407F8DC X-Stat-Signature: q31ejw5w93b41jt4tiahgrh39uo6k3fx Received-SPF: none (bytedance.com>: No applicable sender policy available) receiver=imf10; identity=mailfrom; envelope-from=""; helo=mail-pg1-f170.google.com; client-ip=209.85.215.170 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1616575878-436921 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 Wed, Mar 24, 2021 at 4:33 PM Michal Hocko wrote: > > On Wed 24-03-21 12:11:35, Muchun Song wrote: > > On Tue, Mar 23, 2021 at 11:04 PM Muchun Song wrote: > > > > > > The pages aren't accounted at the root level, so we cannot uncharge the > > > page to the memsw counter for the root memcg. Fix this. > > > > > > Fixes: 1f47b61fb407 ("mm: memcontrol: fix swap counter leak on swapout from offline cgroup") > > > Signed-off-by: Muchun Song > > > > I am very sorry. I should repent. I suddenly realise the fix is totally > > wrong. Because the @memcg cannot be root memcg when > > @memcg != @swap_memcg. > > I am probably blind but I do not see why this would be the case. > We have memcg != swap_memcg in this branch but we do not know the > neither of the two is root_mem_cgroup, no? If we did knot that we > wouldn't have to check for swap_memcg != root_mem_cgroup. Or do I miss > something? I look at the mem_cgroup_id_get_online() closely. If memcg is root, this function always returns root memcg. So memcg will equal swap_memcg. I apologize for not carefully reviewing the code myself. Thanks. > -- > Michal Hocko > SUSE Labs