diff -r 9e463cb15658 xen/common/cpupool.c
--- a/xen/common/cpupool.c	Mon Feb 07 17:02:46 2011 +0000
+++ b/xen/common/cpupool.c	Tue Feb 08 12:13:35 2011 +0000
@@ -297,6 +297,8 @@
         {
             if ( d->cpupool != c )
                 continue;
+            /* Don't allow a cpu to be moved if there's a live
+             * domain still running on it */
             if ( !d->is_dying )
             {
                 ret = -EBUSY;
diff -r 9e463cb15658 xen/common/schedule.c
--- a/xen/common/schedule.c	Mon Feb 07 17:02:46 2011 +0000
+++ b/xen/common/schedule.c	Tue Feb 08 12:13:35 2011 +0000
@@ -495,6 +495,8 @@
 
             if ( v->processor == cpu )
             {
+                printk("%s: Migrating d%dv%d from cpu %d\n",
+                       __func__, d->domain_id, v->vcpu_id, cpu);
                 set_bit(_VPF_migrating, &v->pause_flags);
                 vcpu_schedule_unlock_irq(v);
                 vcpu_sleep_nosync(v);
@@ -511,7 +513,10 @@
              * all locks.
              */
             if ( v->processor == cpu )
+            {
+                printk("  Migration failed, must retry later.\n");
                 ret = -EAGAIN;
+            }
         }
 
         if ( affinity_broken )