Merge to Fedora kernel-2.6.6-1.422

[linux-2.6.git] / kernel / sched.c

diff --git a/kernel/sched.c b/kernel/sched.c
index 53c92f1..c46921c 100644 (file)
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -1671,11 +1671,8 @@ static runqueue_t *find_busiest_queue(struct sched_group *group)
  * tasks if there is an imbalance.
  *
  * Called with this_rq unlocked.
- *
- * This function is marked noinline to work around a compiler
- * bug with gcc 3.3.3-hammer on x86-64.
  */
-static int noinline load_balance(int this_cpu, runqueue_t *this_rq,
+static int load_balance(int this_cpu, runqueue_t *this_rq,
                        struct sched_domain *sd, enum idle_type idle)
 {
        struct sched_group *group;
@@ -1692,6 +1689,11 @@ static int noinline load_balance(int this_cpu, runqueue_t *this_rq,
        busiest = find_busiest_queue(group);
        if (!busiest)
                goto out_balanced;
+       /*
+        * This should be "impossible", but since load
+        * balancing is inherently racy and statistical,
+        * it could happen in theory.
+        */
        if (unlikely(busiest == this_rq)) {
                WARN_ON(1);
                goto out_balanced;
@@ -1855,6 +1857,15 @@ static void active_load_balance(runqueue_t *busiest, int busiest_cpu)
                }
 
                rq = cpu_rq(push_cpu);
+
+               /*
+                * This condition is "impossible", but since load
+                * balancing is inherently a bit racy and statistical,
+                * it can trigger.. Reported by Bjorn Helgaas on a
+                * 128-cpu setup.
+                */
+               if (unlikely(busiest == rq))
+                       goto next_group;
                double_lock_balance(busiest, rq);
                move_tasks(rq, push_cpu, busiest, 1, sd, IDLE);
                spin_unlock(&rq->lock);