SLUB: Fix locking for hotplug callbacks.

Hotplug callbacks seem to be performed with interrupts enabled. Slub requires
interrupts to be disabled for flushing caches.

Signed-off-by: Christoph Lameter <clameter@sgi.com>

---
 mm/slub.c |   15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

Index: slub/mm/slub.c
===================================================================
--- slub.orig/mm/slub.c	2007-06-01 15:49:50.000000000 -0700
+++ slub/mm/slub.c	2007-06-01 18:08:32.000000000 -0700
@@ -2663,6 +2663,19 @@ static void for_all_slabs(void (*func)(s
 }
 
 /*
+ * Version of __flush_cpu_slab for the case that interrupts
+ * are enabled.
+ */
+static void cpu_slab_flush(struct kmem_cache *s, int cpu)
+{
+	unsigned long flags;
+
+	local_irq_save(flags);
+	__flush_cpu_slab(s, cpu);
+	local_irq_restore(flags);
+}
+
+/*
  * Use the cpu notifier to insure that the cpu slabs are flushed when
  * necessary.
  */
@@ -2676,7 +2689,7 @@ static int __cpuinit slab_cpuup_callback
 	case CPU_UP_CANCELED_FROZEN:
 	case CPU_DEAD:
 	case CPU_DEAD_FROZEN:
-		for_all_slabs(__flush_cpu_slab, cpu);
+		for_all_slabs(cpu_slab_flush, cpu);
 		break;
 	default:
 		break;