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=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 991F4C4361B for ; Tue, 15 Dec 2020 03:06:35 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 3773C22475 for ; Tue, 15 Dec 2020 03:06:35 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 3773C22475 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-foundation.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id C27E96B009E; Mon, 14 Dec 2020 22:06:34 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id BAFA08D0006; Mon, 14 Dec 2020 22:06:34 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id A9F208D0005; Mon, 14 Dec 2020 22:06:34 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0231.hostedemail.com [216.40.44.231]) by kanga.kvack.org (Postfix) with ESMTP id 8D8E66B009E for ; Mon, 14 Dec 2020 22:06:34 -0500 (EST) Received: from smtpin12.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id 53C901DEC for ; Tue, 15 Dec 2020 03:06:34 +0000 (UTC) X-FDA: 77594028708.12.jeans22_4d0579e27420 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin12.hostedemail.com (Postfix) with ESMTP id 3438618001FBD for ; Tue, 15 Dec 2020 03:06:34 +0000 (UTC) X-HE-Tag: jeans22_4d0579e27420 X-Filterd-Recvd-Size: 3137 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf06.hostedemail.com (Postfix) with ESMTP for ; Tue, 15 Dec 2020 03:06:33 +0000 (UTC) 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 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: 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(); _