Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull scheduler fixes from Ingo Molnar.

* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched: Fix migration thread runtime bogosity
  sched,rt: fix isolated CPUs leaving root_task_group indefinitely throttled
  sched,cgroup: Fix up task_groups list
  sched: fix divide by zero at {thread_group,task}_times
  sched, cgroup: Reduce rq->lock hold times for large cgroup hierarchies

1 files changed, 13 insertions, 0 deletions

diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
index 573e1ca..944cb68 100644
--- a/kernel/sched/rt.c
+++ b/kernel/sched/rt.c
@@ -788,6 +788,19 @@ static int do_sched_rt_period_timer(struct rt_bandwidth *rt_b, int overrun)
 	const struct cpumask *span;
 
 	span = sched_rt_period_mask();
+#ifdef CONFIG_RT_GROUP_SCHED
+	/*
+	 * FIXME: isolated CPUs should really leave the root task group,
+	 * whether they are isolcpus or were isolated via cpusets, lest
+	 * the timer run on a CPU which does not service all runqueues,
+	 * potentially leaving other CPUs indefinitely throttled.  If
+	 * isolation is really required, the user will turn the throttle
+	 * off to kill the perturbations it causes anyway.  Meanwhile,
+	 * this maintains functionality for boot and/or troubleshooting.
+	 */
+	if (rt_b == &root_task_group.rt_bandwidth)
+		span = cpu_online_mask;
+#endif
 	for_each_cpu(i, span) {
 		int enqueue = 0;
 		struct rt_rq *rt_rq = sched_rt_period_rt_rq(rt_b, i);