From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753092Ab1AJKJX (ORCPT ); Mon, 10 Jan 2011 05:09:23 -0500 Received: from e23smtp03.au.ibm.com ([202.81.31.145]:44691 "EHLO e23smtp03.au.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751712Ab1AJKJV (ORCPT ); Mon, 10 Jan 2011 05:09:21 -0500 Date: Mon, 10 Jan 2011 15:39:17 +0530 From: Bharata B Rao To: Mike Galbraith Cc: linux-kernel@vger.kernel.org, Peter Zijlstra , Ingo Molnar Subject: Re: [PATCH -tip 2/2] sched: Display autogroup names in /proc/sched_debug. Message-ID: <20110110100917.GH2772@in.ibm.com> Reply-To: bharata@linux.vnet.ibm.com References: <20110110051445.GB2772@in.ibm.com> <20110110051643.GD2772@in.ibm.com> <1294652287.17357.14.camel@marge.simson.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1294652287.17357.14.camel@marge.simson.net> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jan 10, 2011 at 10:38:07AM +0100, Mike Galbraith wrote: > On Mon, 2011-01-10 at 10:46 +0530, Bharata B Rao wrote: > > sched: Display autogroup names in /proc/sched_debug. > > > > Add autogroup name to cfs_rq and tasks information in /proc/sched_debug. > > > > Signed-off-by: Bharata B Rao > > --- > > kernel/sched_debug.c | 8 ++++++++ > > 1 file changed, 8 insertions(+) > > > > --- a/kernel/sched_debug.c > > +++ b/kernel/sched_debug.c > > @@ -92,6 +92,14 @@ static void print_cfs_group_stats(struct > > #ifdef CONFIG_CGROUP_SCHED > > static char * task_group_path(struct task_group *tg) > > { > > +#ifdef CONFIG_SCHED_AUTOGROUP > > + int enabled = ACCESS_ONCE(sysctl_sched_autogroup_enabled); > > + > > + if (enabled && tg->autogroup) { > > + autogroup_path(tg, group_path, PATH_MAX); > > + return group_path; > > + } > > +#endif > > /* > > * May be NULL if the underlying cgroup isn't fully-created yet > > */ > > What prevents the task being moved, and the task group being freed under > you? Looks to me like task_group_path() needs rcu_read_lock(). It is > locked in the other two instances. How about the below? You are right, we need rcu_read_lock() there. Let me spin out an other version with the changes. Thanks, Bharata.