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=-15.7 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,URIBL_BLOCKED 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 0BCB4C4361B for ; Tue, 15 Dec 2020 03:07:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BFE30224B0 for ; Tue, 15 Dec 2020 03:07:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725987AbgLODHK (ORCPT ); Mon, 14 Dec 2020 22:07:10 -0500 Received: from mail.kernel.org ([198.145.29.99]:33686 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725938AbgLODGs (ORCPT ); Mon, 14 Dec 2020 22:06:48 -0500 Date: Mon, 14 Dec 2020 19:06:31 -0800 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1608001593; bh=M0bGpBzvIWDYVFC3o78I25RTIutApyRVzkRwwKDOgZI=; h=From:To:Subject:In-Reply-To:From; b=sn4ruzB/I0ncDwO52YR+APKJB5TUDvV7TlEYs3DBp6bb2NRu6Rac921qPBOJ30afa WRZjTPPNHr289lEB40Mk8ImHvEVchjDjCTUFluAC8h5/obfhCnAlpFESHEhvtfvlu2 uosKelnFJMXn3+Etfi8x9Etzb4FKqwjR2F/SUR1E= From: Andrew Morton To: akpm@linux-foundation.org, areber@redhat.com, chris@chrisdown.name, christian.brauner@ubuntu.com, elver@google.com, esyr@redhat.com, guro@fb.com, hannes@cmpxchg.org, iamjoonsoo.kim@lge.com, keescook@chromium.org, laoar.shao@gmail.com, linux-mm@kvack.org, mhocko@kernel.org, mingo@kernel.org, mm-commits@vger.kernel.org, peterz@infradead.org, shakeelb@google.com, songmuchun@bytedance.com, surenb@google.com, tglx@linutronix.de, torvalds@linux-foundation.org, vdavydov.dev@gmail.com Subject: [patch 058/200] mm: memcg/slab: fix return of child memcg objcg for root memcg Message-ID: <20201215030631.R7W-snAn0%akpm@linux-foundation.org> In-Reply-To: <20201214190237.a17b70ae14f129e2dca3d204@linux-foundation.org> User-Agent: s-nail v14.8.16 Precedence: bulk Reply-To: linux-kernel@vger.kernel.org List-ID: X-Mailing-List: mm-commits@vger.kernel.org From: Muchun Song Subject: mm: memcg/slab: fix return of child memcg objcg for root memcg Consider the following memcg hierarchy. root / \ A B If we failed to get the reference on objcg of memcg A, the get_obj_cgroup_from_current can return the wrong objcg for the root memcg. Link: https://lkml.kernel.org/r/20201029164429.58703-1-songmuchun@bytedance.com Fixes: bf4f059954dc ("mm: memcg/slab: obj_cgroup API") Signed-off-by: Muchun Song Acked-by: Roman Gushchin Cc: Johannes Weiner Cc: Michal Hocko Cc: Vladimir Davydov Cc: Shakeel Butt Cc: Joonsoo Kim Cc: Yafang Shao Cc: Chris Down Cc: Christian Brauner Cc: Peter Zijlstra Cc: Ingo Molnar Cc: Kees Cook Cc: Thomas Gleixner Cc: Eugene Syromiatnikov Cc: Suren Baghdasaryan Cc: Adrian Reber Cc: Marco Elver Signed-off-by: Andrew Morton --- mm/memcontrol.c | 1 + 1 file changed, 1 insertion(+) --- a/mm/memcontrol.c~mm-memcg-slab-fix-return-child-memcg-objcg-for-root-memcg +++ a/mm/memcontrol.c @@ -2975,6 +2975,7 @@ __always_inline struct obj_cgroup *get_o objcg = rcu_dereference(memcg->objcg); if (objcg && obj_cgroup_tryget(objcg)) break; + objcg = NULL; } rcu_read_unlock(); _