Re: [PATCH] cgroup_freezer: fix freezing groups with stopped tasks

[Li Zefan]

Tejun Heo wrote:
> Hello, Michal.
> 
> On Wed, Nov 16, 2011 at 10:50:34PM +0100, Michal Hocko wrote:
>> +/* Task is frozen or will freeze immediately when next it gets woken */
>> +static bool is_task_frozen_enough(struct task_struct *task)
>> +{
>> +	return frozen(task) ||
>> +		(task_is_stopped_or_traced(task) && freezing(task));
>> +}
> 
> Hmmm... w/ pending freezer updates, the above would always return
> %true if there's freezing in progress, which can't be right.  Maybe

Only if the task is stopped/trace.

If we try to freeze a stopped task, it will be kept in freezing state.

> just test stopped/traced?
> 

This can trigger a BUG_ON in update_if_frozen(), because we always count a
stopped task as frozen.

>   http://git.kernel.org/?p=linux/kernel/git/tj/misc.git;a=shortlog;h=refs/heads/pm-freezer
> 
> Thanks.
> 
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