From: Oleg Nesterov <oleg@redhat.com>
To: Matt Helsley <matthltc@us.ibm.com>
Cc: Tejun Heo <tj@kernel.org>, "Rafael J. Wysocki" <rjw@sisk.pl>,
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 18:58:39 +0200 [thread overview]
Message-ID: <20110902165839.GA7478@redhat.com> (raw)
In-Reply-To: <20110902004231.GF1919@count0.beaverton.ibm.com>
On 09/01, Matt Helsley wrote:
>
> On Wed, Aug 31, 2011 at 12:21:07PM +0200, Tejun Heo 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);
This is what I mentioned before, to me this looks like a win.
Why do we need try_to_freeze_cgroup() in this case? "for safety"
could actually mean "hide the bug" ;)
But I agree either way. Rafael, I think 1-4 are fine, but I think
we need the simple 5/4, will send in a minute...
Oleg.
next prev parent reply other threads:[~2011-09-02 17:02 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-08-31 10:21 [PATCH pm-freezer 1/4] cgroup_freezer: fix freezer->state setting bug in freezer_change_state() 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
2011-09-02 16:58 ` Oleg Nesterov [this message]
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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