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=-18.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, 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,USER_AGENT_GIT 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 57959C4161F for ; Tue, 2 Mar 2021 06:39:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2D5D36148E for ; Tue, 2 Mar 2021 06:39:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1573170AbhCBDTl (ORCPT ); Mon, 1 Mar 2021 22:19:41 -0500 Received: from mail.kernel.org ([198.145.29.99]:47790 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S243306AbhCAUXv (ORCPT ); Mon, 1 Mar 2021 15:23:51 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 0EA796511E; Mon, 1 Mar 2021 18:05:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1614621946; bh=YmAebTOCi4twYnF8MKZGDDCVL7SOVN8EifS9QJsyc28=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=0D4rZGeZnY5snqx5QLUux0VvPLe1f9SKv1gioB4weR+L/TGBAF5qU01PbERwPp8kB H5WNAkJJKpReUpVGNttflS3T+t5JM6crPGg9e7oXMepi+sy+R6pqDWW/mYhtPJJ94p lhGJV9MttmR+ULBQTEiUM0VFz+hOgAZApohmUW8Y= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Muchun Song , Shakeel Butt , Roman Gushchin , Johannes Weiner , Michal Hocko , Vladimir Davydov , Andrew Morton , Linus Torvalds Subject: [PATCH 5.11 702/775] mm: memcontrol: fix get_active_memcg return value Date: Mon, 1 Mar 2021 17:14:30 +0100 Message-Id: <20210301161236.060534216@linuxfoundation.org> X-Mailer: git-send-email 2.30.1 In-Reply-To: <20210301161201.679371205@linuxfoundation.org> References: <20210301161201.679371205@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Muchun Song commit 1685bde6b9af55923180a76152036c7fb7176db0 upstream. We use a global percpu int_active_memcg variable to store the remote memcg when we are in the interrupt context. But get_active_memcg always return the current->active_memcg or root_mem_cgroup. The remote memcg (set in the interrupt context) is ignored. This is not what we want. So fix it. Link: https://lkml.kernel.org/r/20210223091101.42150-1-songmuchun@bytedance.com Fixes: 37d5985c003d ("mm: kmem: prepare remote memcg charging infra for interrupt contexts") Signed-off-by: Muchun Song Reviewed-by: Shakeel Butt Reviewed-by: Roman Gushchin Cc: Johannes Weiner Cc: Michal Hocko Cc: Vladimir Davydov Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- mm/memcontrol.c | 10 +++------- 1 file changed, 3 insertions(+), 7 deletions(-) --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -1080,13 +1080,9 @@ static __always_inline struct mem_cgroup rcu_read_lock(); memcg = active_memcg(); - if (memcg) { - /* current->active_memcg must hold a ref. */ - if (WARN_ON_ONCE(!css_tryget(&memcg->css))) - memcg = root_mem_cgroup; - else - memcg = current->active_memcg; - } + /* remote memcg must hold a ref. */ + if (memcg && WARN_ON_ONCE(!css_tryget(&memcg->css))) + memcg = root_mem_cgroup; rcu_read_unlock(); return memcg;