Merge branch 'linus' into tracing/urgent

Merge reason: Merge up to almost-rc6 to pick up latest perfcounters
              (on which we'll queue up a dependent fix)

Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 14 insertions, 1 deletions

diff --git a/kernel/sched_cpupri.c b/kernel/sched_cpupri.c
index e6c251790dde..d014efbf947a 100644
--- a/kernel/sched_cpupri.c
+++ b/kernel/sched_cpupri.c
@@ -81,8 +81,21 @@ int cpupri_find(struct cpupri *cp, struct task_struct *p,
 		if (cpumask_any_and(&p->cpus_allowed, vec->mask) >= nr_cpu_ids)
 			continue;
 
-		if (lowest_mask)
+		if (lowest_mask) {
 			cpumask_and(lowest_mask, &p->cpus_allowed, vec->mask);
+
+			/*
+			 * We have to ensure that we have at least one bit
+			 * still set in the array, since the map could have
+			 * been concurrently emptied between the first and
+			 * second reads of vec->mask.  If we hit this
+			 * condition, simply act as though we never hit this
+			 * priority level and continue on.
+			 */
+			if (cpumask_any(lowest_mask) >= nr_cpu_ids)
+				continue;
+		}
+
 		return 1;
 	}