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From: Tejun Heo <tj@kernel.org>
To: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Cc: lizefan@huawei.com, cgroups@vger.kernel.org, mingo@redhat.com,
	peterz@infradead.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/3] sched, cgroup: reorganize threadgroup locking
Date: Thu, 14 May 2015 11:17:42 -0400	[thread overview]
Message-ID: <20150514151742.GJ11388@htj.duckdns.org> (raw)
In-Reply-To: <20150514010913.GA4441@swordfish>

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
!CONFIG_CGROUP.

Thanks.

-- 
tejun

WARNING: multiple messages have this Message-ID (diff)
From: Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
To: Sergey Senozhatsky
	<sergey.senozhatsky.work-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
Cc: lizefan-hv44wF8Li93QT0dZR+AlfA@public.gmane.org,
	cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	mingo-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org,
	peterz-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org,
	linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Subject: Re: [PATCH 1/3] sched, cgroup: reorganize threadgroup locking
Date: Thu, 14 May 2015 11:17:42 -0400	[thread overview]
Message-ID: <20150514151742.GJ11388@htj.duckdns.org> (raw)
In-Reply-To: <20150514010913.GA4441@swordfish>

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
!CONFIG_CGROUP.

Thanks.

-- 
tejun

  reply	other threads:[~2015-05-14 15:17 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-05-13 20:35 [PATCHSET] cgroup, sched: restructure threadgroup locking and replace it with a percpu_rwsem Tejun Heo
2015-05-13 20:35 ` Tejun Heo
2015-05-13 20:35 ` [PATCH 1/3] sched, cgroup: reorganize threadgroup locking Tejun Heo
2015-05-13 20:35   ` Tejun Heo
2015-05-14  1:09   ` Sergey Senozhatsky
2015-05-14  1:09     ` Sergey Senozhatsky
2015-05-14 15:17     ` Tejun Heo [this message]
2015-05-14 15:17       ` Tejun Heo
2015-05-13 20:35 ` [PATCH 2/3] sched, cgroup: replace signal_struct->group_rwsem with a global percpu_rwsem Tejun Heo
2015-05-19 15:16   ` Peter Zijlstra
2015-05-19 15:51     ` Tejun Heo
2015-05-19 15:51       ` Tejun Heo
2015-05-20 10:05       ` Zefan Li
2015-05-20 10:05         ` Zefan Li
2015-05-21 20:39         ` Tejun Heo
2015-05-21 20:39           ` Tejun Heo
2015-05-24  2:35           ` Zefan Li
2015-05-24  2:35             ` Zefan Li
2015-05-13 20:35 ` [PATCH 3/3] cgroup: simplify threadgroup locking Tejun Heo
2015-05-18 16:34 ` [PATCHSET] cgroup, sched: restructure threadgroup locking and replace it with a percpu_rwsem Tejun Heo
2015-05-18 16:34   ` Tejun Heo
2015-05-18 20:06   ` Peter Zijlstra
2015-05-18 20:06     ` Peter Zijlstra
2015-05-27  0:34 ` Tejun Heo
2015-05-27  0:34   ` Tejun Heo

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