Messages in this thread | | | Date | Tue, 23 Oct 2012 18:14:14 +0200 | From | Oleg Nesterov <> | Subject | Re: [PATCH 5/7] cgroup_freezer: allow moving tasks in and out of a frozen cgroup |
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On 10/22, Tejun Heo wrote: > > Hello, > > On Mon, Oct 22, 2012 at 09:25:06PM +0200, Oleg Nesterov wrote: > > > @@ -190,12 +201,12 @@ static void freezer_fork(struct task_struct *task) > > > goto out; > > > > > > spin_lock_irq(&freezer->lock); > > > - BUG_ON(freezer->state == CGROUP_FROZEN); > > > - > > > - /* Locking avoids race with FREEZING -> THAWED transitions. */ > > > - if (freezer->state == CGROUP_FREEZING) > > > + /* > > > + * @task might have been just migrated into a FROZEN cgroup. > > > > Confused. If it was migrated, then freezer_attach() should take care > > do freeze_task? > > Hmmm... there's a window where a task is migrated but ->attach() > hasn't completed yet, so freezer_attach() might not have kicked in > yet.
Yes, I see.
Indeed, cgroup_task_migrate() is called before ->attach().
Thanks!
Oleg.
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