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From: Tejun Heo <tj@kernel.org>
To: Frederic Weisbecker <fweisbec@gmail.com>
Cc: paul@paulmenage.org, rjw@sisk.pl, lizf@cn.fujitsu.com,
	linux-pm@lists.linux-foundation.org,
	linux-kernel@vger.kernel.org,
	containers@lists.linux-foundation.org, matthltc@us.ibm.com,
	akpm@linux-foundation.org, oleg@redhat.com,
	kamezawa.hiroyu@Jp.fujitsu.com
Subject: Re: [PATCH 03/10] threadgroup: extend threadgroup_lock() to cover exit and exec
Date: Mon, 21 Nov 2011 14:03:26 -0800	[thread overview]
Message-ID: <20111121220326.GM25776@google.com> (raw)
In-Reply-To: <20111114135404.GD9446@somewhere>

On Mon, Nov 14, 2011 at 02:54:08PM +0100, Frederic Weisbecker wrote:
> > Also note this is currently protected by the tasklist readlock. Cred guard mutex is
> > certainly better, I just don't remember if you remove the tasklist lock in a
> > further patch.
> 
> Ah recalling what Ben Blum said, we also need the leader to stay stable because it
> is excpected to be passed in ->can_attach(), ->attach(), ->cancel_attach(), ...
> Although that's going to change after your patches that pass a flex array.

Not really without locking out exec.  The thing is whoever is exec'ing
will be the leader and we can't guarantee that the first in the flex
array is always the leader.  One method may see it as the leader, the
next one might not.

Thanks.

-- 
tejun

  reply	other threads:[~2011-11-21 22:03 UTC|newest]

Thread overview: 56+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-11-01 23:46 [PATCHSET] cgroup: stable threadgroup during attach & subsys methods consolidation Tejun Heo
2011-11-01 23:46 ` [PATCH 01/10] cgroup: add cgroup_root_mutex Tejun Heo
2011-11-04  8:38   ` KAMEZAWA Hiroyuki
2011-11-01 23:46 ` [PATCH 02/10] threadgroup: rename signal->threadgroup_fork_lock to ->group_rwsem Tejun Heo
2011-11-04  8:40   ` KAMEZAWA Hiroyuki
2011-11-04 15:16     ` Tejun Heo
2011-11-01 23:46 ` [PATCH 03/10] threadgroup: extend threadgroup_lock() to cover exit and exec Tejun Heo
2011-11-04  8:45   ` KAMEZAWA Hiroyuki
2011-11-13 16:44   ` Frederic Weisbecker
2011-11-14 13:54     ` Frederic Weisbecker
2011-11-21 22:03       ` Tejun Heo [this message]
2011-11-23 14:34         ` Frederic Weisbecker
2011-11-21 21:58     ` Tejun Heo
2011-11-23 14:02       ` Frederic Weisbecker
2011-11-24 21:22         ` Tejun Heo
2011-11-13 18:20   ` Frederic Weisbecker
2011-11-24 22:50   ` [PATCH UPDATED " Tejun Heo
2011-11-25  4:02     ` Linus Torvalds
2011-11-27 19:21       ` Tejun Heo
2011-11-27 21:25         ` Tejun Heo
2011-12-01 19:29           ` Tejun Heo
2011-11-25 14:01     ` Frederic Weisbecker
2011-11-27 19:30       ` Tejun Heo
2011-12-02 16:28         ` Frederic Weisbecker
2011-12-05 18:43           ` Tejun Heo
2011-12-07 15:30             ` Frederic Weisbecker
2011-12-07 18:22               ` Tejun Heo
2011-12-08 20:50                 ` [PATCH UPDATED AGAIN " Tejun Heo
2011-12-09 23:42                   ` Frederic Weisbecker
2011-12-13  1:33                     ` Tejun Heo
2011-12-13  2:17                       ` Tejun Heo
2011-11-01 23:46 ` [PATCH 04/10] cgroup: always lock threadgroup during migration Tejun Heo
2011-11-04  8:54   ` KAMEZAWA Hiroyuki
2011-11-04 15:21     ` Tejun Heo
2011-11-14 18:46   ` Frederic Weisbecker
2011-11-14 18:52     ` Frederic Weisbecker
2011-11-21 22:05       ` Tejun Heo
2011-11-01 23:46 ` [PATCH 05/10] cgroup: subsys->attach_task() should be called after migration Tejun Heo
2011-11-14 20:06   ` Frederic Weisbecker
2011-11-21 22:04     ` Tejun Heo
2011-11-01 23:46 ` [PATCH 06/10] cgroup: improve old cgroup handling in cgroup_attach_proc() Tejun Heo
2011-11-14 20:37   ` Frederic Weisbecker
2011-11-01 23:46 ` [PATCH 07/10] cgroup: introduce cgroup_taskset and use it in subsys->can_attach(), cancel_attach() and attach() Tejun Heo
2011-11-14 21:16   ` Frederic Weisbecker
2011-11-01 23:46 ` [PATCH 08/10] cgroup: don't use subsys->can_attach_task() or ->attach_task() Tejun Heo
2011-11-04  9:08   ` KAMEZAWA Hiroyuki
2011-11-14 23:54   ` Frederic Weisbecker
2011-11-01 23:46 ` [PATCH 09/10] cgroup, cpuset: don't use ss->pre_attach() Tejun Heo
2011-11-15  0:51   ` Frederic Weisbecker
2011-11-01 23:46 ` [PATCH 10/10] cgroup: kill subsys->can_attach_task(), pre_attach() and attach_task() Tejun Heo
2011-11-04  9:10   ` KAMEZAWA Hiroyuki
2011-11-15  0:54   ` Frederic Weisbecker
2011-11-21 22:07 ` [PATCHSET] cgroup: stable threadgroup during attach & subsys methods consolidation Tejun Heo
2011-11-22  2:27   ` Li Zefan
2011-11-22 16:20     ` Tejun Heo
2011-11-24 22:51 ` Tejun Heo

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