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From: Tejun Heo <tj@kernel.org>
To: Matt Helsley <matthltc@us.ibm.com>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>,
	Oleg Nesterov <oleg@redhat.com>,
	Paul Menage <paul@paulmenage.org>,
	containers@lists.linux-foundation.org,
	linux-pm@lists.linux-foundation.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH pm-freezer 1/4] cgroup_freezer: fix freezer->state setting bug in freezer_change_state()
Date: Fri, 2 Sep 2011 11:50:16 +0900	[thread overview]
Message-ID: <20110902025016.GI2752@htj.dyndns.org> (raw)
In-Reply-To: <20110902004231.GF1919@count0.beaverton.ibm.com>

Hello, Matt.

On Thu, Sep 01, 2011 at 05:42:31PM -0700, Matt Helsley wrote:
> >  	case CGROUP_FROZEN:
> > -		atomic_inc(&system_freezing_cnt);
> > -		retval = try_to_freeze_cgroup(cgroup, freezer);
> > +		if (freezer->state == CGROUP_THAWED) {
> > +			freezer->state = CGROUP_FREEZING;
> > +			atomic_inc(&system_freezing_cnt);
> > +			retval = try_to_freeze_cgroup(cgroup, freezer);
> 
> This still doesn't look quite right. If the cgroup is FREEZING it should
> also call try_to_freeze_cgroup(). I think this is what's needed:
> 
> 		if (freezer->state == CGROUP_THAWED)
> 			atomic_inc(&system_freezing_cnt);
> 		freezer->state = CGROUP_FREEZING;
> 		retval = try_to_freeze_cgroup(cgroup, freezer);

Does this make any difference?  Tasks can't migrate if the cgroups are
freezing and freezing state is inherited through forks.  But yeah
doing that for both THAWED and FROZEN might still be a good idea for
safety.

Thanks.

-- 
tejun

  reply	other threads:[~2011-09-02  2:50 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-08-31 10:21 Tejun Heo
2011-08-31 10:21 ` [PATCH pm-freezer 2/4] freezer: set PF_NOFREEZE on a dying task right before TASK_DEAD " Tejun Heo
2011-08-31 10:22   ` [PATCH pm-freezer 3/4] freezer: restructure __refrigerator() Tejun Heo
2011-08-31 10:22     ` [PATCH pm-freezer 4/4] freezer: use lock_task_sighand() in fake_signal_wake_up() Tejun Heo
2011-09-02 17:08     ` [PATCH pm-freezer 3/4] freezer: restructure __refrigerator() Oleg Nesterov
2011-08-31 18:08 ` [PATCH pm-freezer 1/4] cgroup_freezer: fix freezer->state setting bug in freezer_change_state() Oleg Nesterov
2011-09-02  0:42 ` Matt Helsley
2011-09-02  2:50   ` Tejun Heo [this message]
2011-09-02 16:58   ` Oleg Nesterov
2011-09-02 17:08     ` Tejun Heo
2011-09-02 17:15       ` Oleg Nesterov
2011-09-02 17:31         ` Tejun Heo
2011-09-02 17:30       ` Oleg Nesterov
2011-09-02 18:31     ` Matt Helsley
  -- strict thread matches above, loose matches on Subject: below --
2011-08-29 14:04 Tejun Heo
2011-08-29 16:00 ` Oleg Nesterov

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