slab: Convert to hotplug state machine

Install the callbacks via the state machine.

Signed-off-by: Richard Weinberger <richard@nod.at>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Reviewed-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: linux-mm@kvack.org
Cc: rt@linutronix.de
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Christoph Lameter <cl@linux.com>
Link: http://lkml.kernel.org/r/20160823125319.abeapfjapf2kfezp@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

diff --git a/kernel/cpu.c b/kernel/cpu.c
index 0c0d4b2..7c78387 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -24,6 +24,7 @@
 #include <linux/irq.h>
 #include <linux/smpboot.h>
 #include <linux/relay.h>
+#include <linux/slab.h>
 
 #include <trace/events/power.h>
 #define CREATE_TRACE_POINTS
@@ -1278,6 +1279,11 @@
 		.startup.single		= relay_prepare_cpu,
 		.teardown.single	= NULL,
 	},
+	[CPUHP_SLAB_PREPARE] = {
+		.name			= "slab:prepare",
+		.startup.single		= slab_prepare_cpu,
+		.teardown.single	= slab_dead_cpu,
+	},
 	[CPUHP_RCUTREE_PREP] = {
 		.name			= "RCU/tree:prepare",
 		.startup.single		= rcutree_prepare_cpu,