mm/page_alloc: Convert to hotplug state machine

Install the callbacks via the state machine.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-mm@kvack.org
Cc: rt@linutronix.de
Link: http://lkml.kernel.org/r/20161103145021.28528-7-bigeasy@linutronix.deSigned-off-by: Thomas Gleixner <tglx@linutronix.de>

include/linux/cpuhotplug.h

@@ -35,6 +35,7 @@ enum cpuhp_state {
 	CPUHP_MM_MEMCQ_DEAD,
 	CPUHP_PERCPU_CNT_DEAD,
 	CPUHP_RADIX_DEAD,
+	CPUHP_PAGE_ALLOC_DEAD,
 	CPUHP_WORKQUEUE_PREP,
 	CPUHP_POWER_NUMA_PREPARE,
 	CPUHP_HRTIMERS_PREPARE,

mm/page_alloc.c

@@ -6491,12 +6491,9 @@ void __init free_area_init(unsigned long *zones_size)
 			__pa(PAGE_OFFSET) >> PAGE_SHIFT, NULL);
 }
 
-static int page_alloc_cpu_notify(struct notifier_block *self,
-				 unsigned long action, void *hcpu)
+static int page_alloc_cpu_dead(unsigned int cpu)
 {
-	int cpu = (unsigned long)hcpu;
 
-	if (action == CPU_DEAD || action == CPU_DEAD_FROZEN) {
 	lru_add_drain_cpu(cpu);
 	drain_pages(cpu);
 
@@ -6516,13 +6513,17 @@ static int page_alloc_cpu_notify(struct notifier_block *self,
 	 * race with what we are doing.
 	 */
 	cpu_vm_stats_fold(cpu);
-	}
-	return NOTIFY_OK;
+	return 0;
 }
 
 void __init page_alloc_init(void)
 {
-	hotcpu_notifier(page_alloc_cpu_notify, 0);
+	int ret;
+
+	ret = cpuhp_setup_state_nocalls(CPUHP_PAGE_ALLOC_DEAD,
+					"mm/page_alloc:dead", NULL,
+					page_alloc_cpu_dead);
+	WARN_ON(ret < 0);
 }
 
 /*