SLUB: fix locking for hotplug callbacks

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

Signed-off-by: Christoph Lameter <clameter@sgi.com>
Cc: Michal Piotrowski <michal.k.k.piotrowski@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 14 insertions, 1 deletions

diff --git a/mm/slub.c b/mm/slub.c
index 238c5a6ee896..51663a3c3c24 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -2608,6 +2608,19 @@ static void for_all_slabs(void (*func)(struct kmem_cache *, int), int cpu)
 }
 
 /*
+ * 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.
  */
@@ -2621,7 +2634,7 @@ static int __cpuinit slab_cpuup_callback(struct notifier_block *nfb,
         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;