linux-kernel - Re: 2.6.22-rc3-mm1

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Date:	Thu, 31 May 2007 11:57:23 -0700 (PDT)
From:	Christoph Lameter <clameter@....com>
To:	Andrew Morton <akpm@...ux-foundation.org>
cc:	Michal Piotrowski <michal.k.k.piotrowski@...il.com>,
	linux-kernel@...r.kernel.org, "Rafael J. Wysocki" <rjw@...k.pl>,
	Satoru Takeuchi <takeuchi_satoru@...fujitsu.com>
Subject: Re: 2.6.22-rc3-mm1

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@....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;
 
-
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