From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754696AbdCFUMK (ORCPT ); Mon, 6 Mar 2017 15:12:10 -0500 Received: from mail-yw0-f174.google.com ([209.85.161.174]:33269 "EHLO mail-yw0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753658AbdCFUMD (ORCPT ); Mon, 6 Mar 2017 15:12:03 -0500 Date: Mon, 6 Mar 2017 15:12:00 -0500 From: Tejun Heo To: cgroups@vger.kernel.org Cc: LKML , Mike Galbraith , kernel-team@fb.com Subject: Re: [PATCH cgroup/for-4.10-fixes] cgroup/pids: remove spurious suspicious RCU usage warning Message-ID: <20170306201200.GI19696@htj.duckdns.org> References: <1487585723.8499.5.camel@gmx.de> <20170301174452.GE3662@htj.duckdns.org> <1488391071.4812.2.camel@gmx.de> <20170301203907.GF3662@htj.duckdns.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170301203907.GF3662@htj.duckdns.org> User-Agent: Mutt/1.7.1 (2016-10-04) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Mar 01, 2017 at 03:39:07PM -0500, Tejun Heo wrote: > pids_can_fork() is special in that the css association is guaranteed > to be stable throughout the function and thus doesn't need RCU > protection around task_css access. When determining the css to charge > the pid, task_css_check() is used to override the RCU sanity check. > > While adding a warning message on fork rejection from pids limit, > 135b8b37bd91 ("cgroup: Add pids controller event when fork fails > because of pid limit") incorrectly added a task_css access which is > neither RCU protected or explicitly annotated. This triggers the > following suspicious RCU usage warning when RCU debugging is enabled. Applied to cgroup/for-4.11-fixes. -- tejun