So if the group ever gets throttled, it will never wake up again.
Reported-by: N"Daniel K." <dk@uw.no>
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Tested-by: NDaniel K. <dk@uw.no>
Signed-off-by: NIngo Molnar <mingo@elte.hu>