Re: [PATCH 1/3] sched, cgroup: reorganize threadgroup locking

From: Tejun Heo
Date: Thu May 14 2015 - 11:17:50 EST

Hello, Sergey.

On Thu, May 14, 2015 at 10:09:13AM +0900, Sergey Senozhatsky wrote:
> > +static inline void threadgroup_change_begin(struct task_struct *tsk)
> > {
> > - down_write(&tsk->signal->group_rwsem);
> > + might_sleep();
> I think cgroup_threadgroup_change_begin()->down_read() already does
> might_sleep() check.

Sure but it's a layering thing. threadgroup_change_begin() should be
called from a blockable context whether the hook users actually make
use of it or not. e.g. We want might_sleep() even when


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