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=-12.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT 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 D182DC55179 for ; Wed, 28 Oct 2020 22:25:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7ADDC20706 for ; Wed, 28 Oct 2020 22:25:16 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=bytedance-com.20150623.gappssmtp.com header.i=@bytedance-com.20150623.gappssmtp.com header.b="GnFZV28/" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732838AbgJ1WZK (ORCPT ); Wed, 28 Oct 2020 18:25:10 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54818 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732785AbgJ1WY7 (ORCPT ); Wed, 28 Oct 2020 18:24:59 -0400 Received: from mail-pf1-x441.google.com (mail-pf1-x441.google.com [IPv6:2607:f8b0:4864:20::441]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DBDB2C0613CF for ; Wed, 28 Oct 2020 15:24:59 -0700 (PDT) Received: by mail-pf1-x441.google.com with SMTP id x13so625538pfa.9 for ; Wed, 28 Oct 2020 15:24:59 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bytedance-com.20150623.gappssmtp.com; s=20150623; h=from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=gP9leRSqd8Nt5uw/ZcHLxalg6StnlmANhYwqDz5BamY=; b=GnFZV28/BNLRDucvzLESFv3OK7W6Iffx80nxt4gJX1KhQieE7APUfRH855/sp8RpMp cgkPejLvI+G6njV9mAmeo8VpZR4SfRadMjAssX2yRNc0iM3vyKnAhArixSQD58RO3L72 Z0dOyUvEwxRX46FND2HUmFnhDDWdGNDCh5D+vNMyuk0wOXQ0ey1QMESV6UzxiDxR0yMU I/NSyZH3V7OUkd/ZNH6L5ToixcPb8J95qJPY7X1JOPEGvzroGJRZk1n/vBLocJO8sU4I fcnSEqdRLC/8x96lYmo1J1CBnTvGU14rV/VVdMwwMHdnccSu1XPj2SlK3p3yIP7wc1RY 4KLQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=gP9leRSqd8Nt5uw/ZcHLxalg6StnlmANhYwqDz5BamY=; b=lULs5rqNqXeZQUpQUcee+KRRqBuL8V7umNlGZ4eeonUfJGS4m092VmPtLLSgYhW+xx RuW48AccsYNy4bou3775hR1ZQAPFgQMryvY4R+hFqiEjFUfEXCeAZR8krE2ejRTMGxYo kQ+UVLkquyjgcRyr13X4k/mB5/5pHTm32DzxVvtrVNOl7HsnVNdk9xYmBsrYnMcCdJiO MHNEvFDEEKWR/os2RzR0LKFacPETZ8++Ub75yXlig7Yop+Gw3puAnxz35NQfM9JiW08e qcCtsIiuN1qhJY5ZYI++Dz7SEMILuvO9r8TXyqnVwo02581C0AzLqLHFe9v2hcaWa0bc 4aLQ== X-Gm-Message-State: AOAM532KhowI+V2uvNXtkOwTfwH617P50pyfi7BmiILxj5fYN0Hvr0oX zhV1lSeY/VzRjnRQLfVuWjlBDKUghenzGHK9 X-Google-Smtp-Source: ABdhPJzaRhN3aDdXWQ0D5XcrckptuF92X7FGcRacXma9zoZkUg7BhB9XvJmIZJEeUtmL/cOvXiejSQ== X-Received: by 2002:a63:4c19:: with SMTP id z25mr4603006pga.58.1603857050037; Tue, 27 Oct 2020 20:50:50 -0700 (PDT) Received: from Smcdef-MBP.local.net ([103.136.220.89]) by smtp.gmail.com with ESMTPSA id s8sm3412273pjn.46.2020.10.27.20.50.42 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Tue, 27 Oct 2020 20:50:49 -0700 (PDT) From: Muchun Song To: hannes@cmpxchg.org, mhocko@kernel.org, vdavydov.dev@gmail.com, akpm@linux-foundation.org, shakeelb@google.com, guro@fb.com, iamjoonsoo.kim@lge.com, laoar.shao@gmail.com, chris@chrisdown.name, christian.brauner@ubuntu.com, peterz@infradead.org, mingo@kernel.org, keescook@chromium.org, tglx@linutronix.de, esyr@redhat.com, surenb@google.com, areber@redhat.com, elver@google.com Cc: linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, linux-mm@kvack.org, Muchun Song Subject: [PATCH v2] mm: memcg/slab: Fix return child memcg objcg for root memcg Date: Wed, 28 Oct 2020 11:50:10 +0800 Message-Id: <20201028035013.99711-1-songmuchun@bytedance.com> X-Mailer: git-send-email 2.21.0 (Apple Git-122) MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Consider the following memcg hierarchy. root / \ A B If we get the objcg of memcg A failed, 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; } rcu_read_unlock(); -- 2.20.1