Re: [patch] cgroups: disallow attaching kthreadd

From: Tejun Heo
Date: Mon Apr 23 2012 - 14:05:10 EST

On Sat, Apr 21, 2012 at 09:13:46AM +0200, Mike Galbraith wrote:
> On Sat, 2012-04-21 at 14:54 +0800, Li Zefan wrote:
> > forgot rcu_read_unlock() ?
> Eek, we don't need another one of those. Thanks.
> > Otherwise Acked-by: Li Zefan <lizefan@xxxxxxxxxx>
> cgroups: disallow attaching kthreadd or PF_THREAD_BOUND threads
> Allowing kthreadd to be moved to a non-root group makes no sense, it being
> a global resource, and needlessly leads unsuspecting users toward trouble.
> 1. An RT workqueue worker thread spawned in a task group with no rt_runtime
> allocated is not schedulable. Simple user error, but harmful to the box.
> 2. A worker thread which acquires PF_THREAD_BOUND can never leave a cpuset,
> rendering the cpuset immortal.
> Save the user some unexpected trouble, just say no.
> Signed-off-by: Mike Galbraith <mgalbraith@xxxxxxx>
> Acked-by: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
> Acked-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> Acked-by: Li Zefan <lizefan@xxxxxxxxxx>

Applied to cgroup/for-3.5. Thanks.

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