Re: 2.6.22-rc3-mm1

Christoph Lameter
2007-05-31T18:57:35Z

On Thu, 31 May 2007, Andrew Morton wrote:

> we're not disbling local irqs on the cpu hotplug path.
>
> Could do local_irq_disable() in slab_cpuup_callback(), I guess.

Ahh I see.

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>

Index: slub/mm/slub.c
===================================================================
--- slub.orig/mm/slub.c 2007-05-31 11:49:48.000000000 -0700
+++ slub/mm/slub.c 2007-05-31 11:54:09.000000000 -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;