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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1EDE4C433EF for ; Wed, 9 Mar 2022 18:10:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234538AbiCISLc (ORCPT ); Wed, 9 Mar 2022 13:11:32 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51908 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229596AbiCISLb (ORCPT ); Wed, 9 Mar 2022 13:11:31 -0500 Received: from mail-pl1-x630.google.com (mail-pl1-x630.google.com [IPv6:2607:f8b0:4864:20::630]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 245AE40E42; Wed, 9 Mar 2022 10:10:32 -0800 (PST) Received: by mail-pl1-x630.google.com with SMTP id 9so2662348pll.6; Wed, 09 Mar 2022 10:10:32 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=sender:date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=gwB5ul7ug54L0VuMLgVdXhYXbW5z5+vlezaYRrDt3pk=; b=Smg69TaCEAFM4UcbwfjW0Sb6bBoNfiS3bSVBjeqfS1HLAUTS3+ZD9/kstjcPZT8jf+ ZioEdEM9xhJe2i864YcvhkeqUmhixiqi17hg8awoiQv3+8GzIj/SqZR6beNw+7vdv76O UaToexqeCfRPh9+BzsOV5QGOXc/TXlN/bU9FJwH56V4zCpNmI7iuUH9+pqLA/UFy1zsm Hv9Ng+D4k/8Sf1gNC5WsxDWOj8FGbr6ad+LoxvumyjVE+6poyRSC7Hurq52udeFAQuP+ oPWVKX9XM1mSnRnDmKfy+16Ja8HL17kw4cw7A7UlTMaCQuXAKHg98L4uQhZUrt8oOjcT hJSw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:sender:date:from:to:cc:subject:message-id :references:mime-version:content-disposition:in-reply-to; bh=gwB5ul7ug54L0VuMLgVdXhYXbW5z5+vlezaYRrDt3pk=; b=4mSroIESDE0vv4lYV7HpL/WgaiOWt4yFTxwJPuwlYiP8ioTJUxPgMM29ues8ZZWoYt iS2IusCyP2fk03Pkm8ZAILYyX+VYeLlENifdjjP4rp2zXVeO5ol22DnuYVy1gR802biu ehHfmQGqOvGQI5UDY25cD3O8oK/GpQvkXAWuAZI9P2lE+5QZj58BLhmkWzYuADbiI2sd GEXyv1h2wAnJaWcM6GwB2yxwym9Fxhh2ZhXSsuwioc4DTpKG/r53grnUWXwyt3C/TLl3 Djz6rKmCGERHA4fTXVLEco0ewpxcqXciw7krTt91DNai6naH5Pa89wuyy8s4btlpt4jf 5olg== X-Gm-Message-State: AOAM530pP7jL9+Je9++fJs9iLj1XwsjOgyDl1/ypK8kZFkvLNVumgvmc DiC4HHiTYuoK2AFTzTqDdxw= X-Google-Smtp-Source: ABdhPJx07Q/0H+LE4IMZJub5t+Njk4j2aFEG5ihccN0LDsgTelrHKJZw5op8nDLZ4b7cytOcs0tc2w== X-Received: by 2002:a17:902:ea12:b0:151:dbbd:aeb8 with SMTP id s18-20020a170902ea1200b00151dbbdaeb8mr643100plg.157.1646849431498; Wed, 09 Mar 2022 10:10:31 -0800 (PST) Received: from localhost (2603-800c-1a02-1bae-e24f-43ff-fee6-449f.res6.spectrum.com. [2603:800c:1a02:1bae:e24f:43ff:fee6:449f]) by smtp.gmail.com with ESMTPSA id j9-20020a056a00130900b004f73df40914sm3846878pfu.82.2022.03.09.10.10.30 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 09 Mar 2022 10:10:31 -0800 (PST) Sender: Tejun Heo Date: Wed, 9 Mar 2022 08:10:29 -1000 From: Tejun Heo To: Chengming Zhou Cc: lizefan.x@bytedance.com, hannes@cmpxchg.org, peterz@infradead.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, songmuchun@bytedance.com, Linux Kernel Functional Testing , syzbot+16e3f2c77e7c5a0113f9@syzkaller.appspotmail.com, Zhouyi Zhou Subject: Re: [PATCH linux-next] cgroup: fix suspicious rcu_dereference_check() usage warning Message-ID: References: <20220305034103.57123-1-zhouchengming@bytedance.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220305034103.57123-1-zhouchengming@bytedance.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Mar 05, 2022 at 11:41:03AM +0800, Chengming Zhou wrote: > task_css_set_check() will use rcu_dereference_check() to check for > rcu_read_lock_held() on the read-side, which is not true after commit > dc6e0818bc9a ("sched/cpuacct: Optimize away RCU read lock"). This > commit drop explicit rcu_read_lock(), change to RCU-sched read-side > critical section. So fix the RCU warning by adding check for > rcu_read_lock_sched_held(). > > Fixes: dc6e0818bc9a ("sched/cpuacct: Optimize away RCU read lock") > Reported-by: Linux Kernel Functional Testing > Reported-by: syzbot+16e3f2c77e7c5a0113f9@syzkaller.appspotmail.com > Tested-by: Zhouyi Zhou > Signed-off-by: Chengming Zhou > --- > include/linux/cgroup.h | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h > index 1e356c222756..0d1ada8968d7 100644 > --- a/include/linux/cgroup.h > +++ b/include/linux/cgroup.h > @@ -450,6 +450,7 @@ extern struct mutex cgroup_mutex; > extern spinlock_t css_set_lock; > #define task_css_set_check(task, __c) \ > rcu_dereference_check((task)->cgroups, \ > + rcu_read_lock_sched_held() || \ > lockdep_is_held(&cgroup_mutex) || \ > lockdep_is_held(&css_set_lock) || \ > ((task)->flags & PF_EXITING) || (__c)) Acked-by: Tejun Heo Thanks. -- tejun