sched_rt: Fix overload bug on rt group scheduling

Fixes an easily triggerable BUG() when setting process affinities.

Make sure to count the number of migratable tasks in the same place:
the root rt_rq. Otherwise the number doesn't make sense and we'll hit
the BUG in set_cpus_allowed_rt().

Also, make sure we only count tasks, not groups (this is probably
already taken care of by the fact that rt_se->nr_cpus_allowed will be 0
for groups, but be more explicit)

Tested-by: Thomas Gleixner <tglx@linutronix.de>
CC: stable@kernel.org
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Gregory Haskins <ghaskins@novell.com>
LKML-Reference: <1247067476.9777.57.camel@twins>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 1 insertions, 0 deletions

diff --git a/kernel/sched.c b/kernel/sched.c
index 7c9098d186e6..a17f3d9a8bfa 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -493,6 +493,7 @@ struct rt_rq {
 #endif
 #ifdef CONFIG_SMP
         unsigned long rt_nr_migratory;
+        unsigned long rt_nr_total;
         int overloaded;
         struct plist_head pushable_tasks;
 #endif