slab: shut down cache_reaper when cpu goes down

Shutdown the cache_reaper if the cpu is brought down and set the
cache_reap.func to NULL.  Otherwise hotplug shuts down the reaper for good.

Signed-off-by: Christoph Lameter <clameter@sgi.com>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 14 insertions, 0 deletions

diff --git a/mm/slab.c b/mm/slab.c
index cceb347a354e..1a7a10de2a4d 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -1279,6 +1279,20 @@ static int __cpuinit cpuup_callback(struct notifier_block *nfb,
                 start_cpu_timer(cpu);
                 break;
 #ifdef CONFIG_HOTPLUG_CPU
+        case CPU_DOWN_PREPARE:
+                /*
+                 * Shutdown cache reaper. Note that the cache_chain_mutex is
+                 * held so that if cache_reap() is invoked it cannot do
+                 * anything expensive but will only modify reap_work
+                 * and reschedule the timer.
+                */
+                cancel_rearming_delayed_work(&per_cpu(reap_work, cpu));
+                /* Now the cache_reaper is guaranteed to be not running. */
+                per_cpu(reap_work, cpu).work.func = NULL;
+                break;
+        case CPU_DOWN_FAILED:
+                start_cpu_timer(cpu);
+                break;
         case CPU_DEAD:
                 /*
                  * Even if all the cpus of a node are down, we don't free the