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 <efault@gmx.de> Acked-by: David Rientjes <rientjes@google.com> Acked-by: Paul Menage <paul@paulmenage.org> Cc: Tejun Heo <htejun@gmail.com> Cc: Li Zefan <lizf@cn.fujitsu.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>