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 E09C7C433E0 for ; Wed, 24 Feb 2021 20:06:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9D15B64F23 for ; Wed, 24 Feb 2021 20:06:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234274AbhBXUGT (ORCPT ); Wed, 24 Feb 2021 15:06:19 -0500 Received: from mail.kernel.org ([198.145.29.99]:56140 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234906AbhBXUFv (ORCPT ); Wed, 24 Feb 2021 15:05:51 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 31F4764F11; Wed, 24 Feb 2021 20:04:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1614197063; bh=G31EBYnGYWA+9ziOs13ui7hLFTA9Ds66VuzLUR1+Iv4=; h=Date:From:To:Subject:In-Reply-To:From; b=si5bUio5hFqsEjKRig7n4vmR60gzC42liNYSxQ6OQc3feQk003GyrD0TmiSURD3DK NqjymUnrfzPZHB1usvHOdEf13vscSZfoeV6hQINEKMuno0e5H0/KG4D1aFDvMsr/Te MmT+prNuBlA4QG+t3+FVRVtGntzQenx+rTuRsyWI= Date: Wed, 24 Feb 2021 12:04:22 -0800 From: Andrew Morton To: akpm@linux-foundation.org, guro@fb.com, hannes@cmpxchg.org, linux-mm@kvack.org, mhocko@kernel.org, mm-commits@vger.kernel.org, shakeelb@google.com, songmuchun@bytedance.com, stable@vger.kernel.org, torvalds@linux-foundation.org, vdavydov.dev@gmail.com Subject: [patch 074/173] mm: memcontrol: fix get_active_memcg return value Message-ID: <20210224200422.mMBuJs4L_%akpm@linux-foundation.org> In-Reply-To: <20210224115824.1e289a6895087f10c41dd8d6@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: memcontrol: fix get_active_memcg return value 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 --- mm/memcontrol.c | 10 +++------- 1 file changed, 3 insertions(+), 7 deletions(-) --- a/mm/memcontrol.c~mm-memcontrol-fix-get_active_memcg-return-value +++ a/mm/memcontrol.c @@ -1061,13 +1061,9 @@ 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; _