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From: Frederic Weisbecker <fweisbec@gmail.com>
To: Tejun Heo <tj@kernel.org>
Cc: rjw@sisk.pl, paul@paulmenage.org, lizf@cn.fujitsu.com,
	linux-pm@lists.linux-foundation.org,
	linux-kernel@vger.kernel.org,
	containers@lists.linux-foundation.org, matthltc@us.ibm.com,
	kamezawa.hiroyu@jp.fujitsu.com
Subject: Re: [PATCH 6/6] cgroup: kill subsys->can_attach_task(), pre_attach() and attach_task()
Date: Wed, 31 Aug 2011 15:42:24 +0200	[thread overview]
Message-ID: <20110831134220.GB20598@somewhere> (raw)
In-Reply-To: <20110831070313.GA29179@mtj.dyndns.org>

On Wed, Aug 31, 2011 at 09:03:13AM +0200, Tejun Heo wrote:
> Hello, Frederic.
> 
> On Tue, Aug 30, 2011 at 10:10:32PM +0200, Frederic Weisbecker wrote:
> > In order to keep the fix queued in -mm (https://lkml.org/lkml/2011/8/26/262)
> > the tasks that have failed to migrate should be removed from the iterator
> > so that they are not included in the batch in ->attach().
> 
> I don't think that's a good approach.  It breaks the symmetry when
> calling different callbacks.  What if ->can_attach() allocates
> per-task resources and the task exits in the middle?  I think we
> better lock down fork/exit/exec.  I'll send patches but I'm currently
> moving / traveling w/ limited access to my toys so it might take some
> time.

My task counter subsystem patchset brings a cancel_attach_task() callback
that cancels can_attach_task() effects.

I thought that rebased on top of your patch it's going to be merged inside
cancel_attach() but OTOH we can't cancel the effect of failed migration
on a thread that way.

May be we need to keep a cancel_attach_task() just for that purpose?

  reply	other threads:[~2011-08-31 13:42 UTC|newest]

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-08-25 22:43 [PATCHSET] cgroup: introduce cgroup_taskset and consolidate subsys methods, take#2 Tejun Heo
2011-08-25 22:43 ` [PATCH 1/6] cgroup: subsys->attach_task() should be called after migration Tejun Heo
2011-08-26  4:12   ` KAMEZAWA Hiroyuki
2011-08-25 22:43 ` [PATCH 2/6] cgroup: improve old cgroup handling in cgroup_attach_proc() Tejun Heo
2011-08-26  4:13   ` KAMEZAWA Hiroyuki
2011-08-25 22:43 ` [PATCH 3/6] cgroup: introduce cgroup_taskset and use it in subsys->can_attach(), cancel_attach() and attach() Tejun Heo
2011-08-26  2:38   ` Matt Helsley
2011-08-26  2:48     ` Matt Helsley
2011-08-26  6:40     ` Tejun Heo
2011-08-26 15:54     ` Paul Menage
2011-08-26  4:16   ` KAMEZAWA Hiroyuki
2011-08-25 22:43 ` [PATCH 4/6] cgroup: don't use subsys->can_attach_task() or ->attach_task() Tejun Heo
2011-08-26  4:18   ` KAMEZAWA Hiroyuki
2011-08-25 22:43 ` [PATCH 5/6] cgroup, cpuset: don't use ss->pre_attach() Tejun Heo
2011-08-26  4:19   ` KAMEZAWA Hiroyuki
2011-08-25 22:43 ` [PATCH 6/6] cgroup: kill subsys->can_attach_task(), pre_attach() and attach_task() Tejun Heo
2011-08-26  4:20   ` KAMEZAWA Hiroyuki
2011-08-30 20:10   ` Frederic Weisbecker
2011-08-31  7:03     ` Tejun Heo
2011-08-31 13:42       ` Frederic Weisbecker [this message]
2011-09-01 11:22         ` Tejun Heo
2011-09-01 12:58           ` Frederic Weisbecker
2011-08-25 22:48 ` [PATCHSET] cgroup: introduce cgroup_taskset and consolidate subsys methods, take#2 Tejun Heo
2011-08-26  8:05 ` Li Zefan
2011-08-26 14:09   ` Tejun Heo
2011-08-26 14:56     ` Paul Menage
  -- strict thread matches above, loose matches on Subject: below --
2011-08-23 22:19 [PATCHSET] cgroup: introduce cgroup_taskset and consolidate subsys methods Tejun Heo
2011-08-23 22:20 ` [PATCH 6/6] cgroup: kill subsys->can_attach_task(), pre_attach() and attach_task() Tejun Heo
2011-08-25  9:45   ` Paul Menage

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