sched, autogroup: Fix CONFIG_RT_GROUP_SCHED sched_setscheduler() failure

If CONFIG_RT_GROUP_SCHED is set, __sched_setscheduler() fails due to autogroup
not allocating rt_runtime.  Free unused/unusable rt_se and rt_rq, redirect RT
tasks to the root task group, and tell __sched_setscheduler() that it's ok.

Reported-and-tested-by: Bharata B Rao <bharata@linux.vnet.ibm.com>
Signed-off-by: Mike Galbraith <efault@gmx.de>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1294890890.8089.39.camel@marge.simson.net>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 2 insertions, 1 deletions

diff --git a/kernel/sched.c b/kernel/sched.c
index a0eb0941fa84..6cbff6bd1a60 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -4871,7 +4871,8 @@ recheck:
                  * assigned.
                  */
                 if (rt_bandwidth_enabled() && rt_policy(policy) &&
-                                task_group(p)->rt_bandwidth.rt_runtime == 0) {
+                                task_group(p)->rt_bandwidth.rt_runtime == 0 &&
+                                !task_group_is_autogroup(task_group(p))) {
                         __task_rq_unlock(rq);
                         raw_spin_unlock_irqrestore(&p->pi_lock, flags);
                         return -EPERM;