Index: linux-2.6.19-rc3/kernel/sched.c
===================================================================
--- linux-2.6.19-rc3.orig/kernel/sched.c	2006-10-31 17:12:34.708109060 -0600
+++ linux-2.6.19-rc3/kernel/sched.c	2006-10-31 17:12:47.341034439 -0600
@@ -1932,6 +1932,24 @@ task_hot(struct task_struct *p, unsigned
 }
 
 /*
+ * double_rq_trylock - safely lock two runqueues
+ *
+ * Note this does not disable interrupts like task_rq_lock,
+ * you need to do so manually before calling.
+ */
+static int double_rq_trylock(struct rq *rq1, struct rq *rq2)
+	__acquires(rq1->lock)
+	__acquires(rq2->lock)
+{
+	if (spin_trylock(&rq1->lock)) {
+		if (rq1 == rq2 || spin_trylock(&rq2->lock))
+			return 1;
+		spin_unlock(&rq1->lock);
+	}
+	return 0;
+}
+
+/*
  * double_rq_lock - safely lock two runqueues
  *
  * Note this does not disable interrupts like task_rq_lock,
@@ -2579,11 +2597,12 @@ redo:
 		 * still unbalanced. nr_moved simply stays zero, so it is
 		 * correctly treated as an imbalance.
 		 */
-		double_rq_lock(this_rq, busiest);
-		nr_moved = move_tasks(this_rq, this_cpu, busiest,
+		if (double_rq_trylock(this_rq, busiest)) {
+			nr_moved = move_tasks(this_rq, this_cpu, busiest,
 				      minus_1_or_zero(busiest->nr_running),
 				      imbalance, sd, idle, &all_pinned);
-		double_rq_unlock(this_rq, busiest);
+			double_rq_unlock(this_rq, busiest);
+		}
 
 		/* All tasks on this runqueue were pinned by CPU affinity */
 		if (unlikely(all_pinned)) {