Merge branch 'amd-iommu/2.6.32' of git://git.kernel.org/pub/scm/linux/kernel/git/joro/linux-2.6-iommu into core/iommu

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;
         }