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=-17.4 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_IN_DEF_DKIM_WL autolearn=unavailable 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 44489C2D0A3 for ; Thu, 29 Oct 2020 15:49:01 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 795F420825 for ; Thu, 29 Oct 2020 15:49:00 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="stI5fekX" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 795F420825 Authentication-Results: mail.kernel.org; dmarc=fail (p=reject dis=none) header.from=google.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id B86366B005C; Thu, 29 Oct 2020 11:48:59 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id B378B6B0062; Thu, 29 Oct 2020 11:48:59 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 98B2F6B006C; Thu, 29 Oct 2020 11:48:59 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0205.hostedemail.com [216.40.44.205]) by kanga.kvack.org (Postfix) with ESMTP id 6BC266B005C for ; Thu, 29 Oct 2020 11:48:59 -0400 (EDT) Received: from smtpin29.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id 12001181AEF0B for ; Thu, 29 Oct 2020 15:48:59 +0000 (UTC) X-FDA: 77425396398.29.town76_5e1088a2728e Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin29.hostedemail.com (Postfix) with ESMTP id D4BAC180868D1 for ; Thu, 29 Oct 2020 15:48:58 +0000 (UTC) X-HE-Tag: town76_5e1088a2728e X-Filterd-Recvd-Size: 4474 Received: from mail-lf1-f67.google.com (mail-lf1-f67.google.com [209.85.167.67]) by imf29.hostedemail.com (Postfix) with ESMTP for ; Thu, 29 Oct 2020 15:48:58 +0000 (UTC) Received: by mail-lf1-f67.google.com with SMTP id f9so3950550lfq.2 for ; Thu, 29 Oct 2020 08:48:58 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=N6hFvPTvw/59UWHjYIOWZNWhefGQ9eQg3cKC2KPGwCM=; b=stI5fekXpQhrvKoARPS6AF6qpqpjEK9uc1LX1KLKNec1z0x6yaI9ATroJZ6+pRrtiJ FvADZnyT/zRZVVgZVWol+0ltxgd6Y5ix42oFmmPz1B4V3VaTnokEqQhsTYWVICBUWIku 9Fk5j0+BjuxdxZRChwMI39Yk9ngWlL3BcekHDWpvHzItzJBoi6KSCSEv6qaof6slywA6 Z9ycEF1H96wb+5jRFrczxm3/mBE78YGj9HFBmUeyT77Ei7G5GWeT7iG/OlQqsUaiNa81 mZ/65I1f9jDxJXkblfK/CmELlWosZmafXB34IDtR+1D72hSzwMd7skKYuGU3X9dTZ3t0 F1Zg== 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=N6hFvPTvw/59UWHjYIOWZNWhefGQ9eQg3cKC2KPGwCM=; b=PNoLDfMqwu55KXMWOEoPrw+iplqgqbX2hQ6sGPCyB65/Z1bJzY9E4BtIKPzws5Fy2t KB4W9yKSswHdpDrGTuJokjiQdUPKeZ+A8P9FFf3DlenCfG3bQc4nXeENaej27JKe9UEQ xMXvWCMniVQSfpX3Ttt12oXAtU2qYYeey7BZtEJ5B2u7VFY5MvDqTE2GiVgBtbu1lb68 5KxT9Fadbbn7XK4x9Ab9dkAcdCUipxVtKZcBBmHbmmTrts1wq/jmtJ0cspgVcIMb15Ka iWODI8K4HgG9qYg4i0DMWYWHJvsWq5AqUxCc31pAICsr+ycHCIO/044nNPfbnw0T2720 ZGqQ== X-Gm-Message-State: AOAM533CrVZkuPkJuGWahCTDgAiJyF4sCjHK/t5iY1ANDG9KfGbutyL8 OACHJWJ8XolOYMnsQgCpZJ4Vkh81FPmu63sW4ztsLA== X-Google-Smtp-Source: ABdhPJxTeNSGR9ZhUcP7bCxdClKAWwUmdsXRiTkBvntA3ByspyxCe98ZHStsm58VJLsmgWs1OAlSIfc2hUNNsH6YU7A= X-Received: by 2002:a19:2355:: with SMTP id j82mr1723817lfj.385.1603986536474; Thu, 29 Oct 2020 08:48:56 -0700 (PDT) MIME-Version: 1.0 References: <20201028035013.99711-1-songmuchun@bytedance.com> In-Reply-To: <20201028035013.99711-1-songmuchun@bytedance.com> From: Shakeel Butt Date: Thu, 29 Oct 2020 08:48:45 -0700 Message-ID: Subject: Re: [PATCH v2] mm: memcg/slab: Fix return child memcg objcg for root memcg To: Muchun Song Cc: Johannes Weiner , Michal Hocko , Vladimir Davydov , Andrew Morton , Roman Gushchin , Joonsoo Kim , Yafang Shao , Chris Down , Christian Brauner , "Peter Zijlstra (Intel)" , Ingo Molnar , Kees Cook , Thomas Gleixner , esyr@redhat.com, Suren Baghdasaryan , areber@redhat.com, Marco Elver , LKML , Cgroups , Linux MM Content-Type: text/plain; charset="UTF-8" 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, Oct 27, 2020 at 8:50 PM Muchun Song wrote: > > Consider the following memcg hierarchy. > > root > / \ > A B > > If we get the objcg of memcg A failed, Please fix the above statement. > the get_obj_cgroup_from_current > can return the wrong objcg for the root memcg. > > Fixes: bf4f059954dc ("mm: memcg/slab: obj_cgroup API") > Signed-off-by: Muchun Song > --- > changelog in v2: > 1. Do not use a comparison with the root_mem_cgroup > > mm/memcontrol.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > index 1337775b04f3..8c8b4c3ed5a0 100644 > --- a/mm/memcontrol.c > +++ b/mm/memcontrol.c > @@ -2961,6 +2961,7 @@ __always_inline struct obj_cgroup *get_obj_cgroup_from_current(void) > objcg = rcu_dereference(memcg->objcg); > if (objcg && obj_cgroup_tryget(objcg)) > break; > + objcg = NULL; Roman, in your cleanup, are you planning to have objcg for root memcg as well? > } > rcu_read_unlock(); > > -- > 2.20.1 >