Install the callbacks via the state machine.

Cc: Johannes Weiner <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: [email protected]
Cc: [email protected]
Signed-off-by: Sebastian Andrzej Siewior <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
---
 include/linux/cpuhotplug.h |  1 +
 mm/memcontrol.c            | 24 ++++++++----------------
 2 files changed, 9 insertions(+), 16 deletions(-)

diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h
index 4174083280d7..c622ab349af3 100644
--- a/include/linux/cpuhotplug.h
+++ b/include/linux/cpuhotplug.h
@@ -32,6 +32,7 @@ enum cpuhp_state {
        CPUHP_BLK_MQ_DEAD,
        CPUHP_FS_BUFF_DEAD,
        CPUHP_PRINTK_DEAD,
+       CPUHP_MM_MEMCQ_DEAD,
        CPUHP_WORKQUEUE_PREP,
        CPUHP_POWER_NUMA_PREPARE,
        CPUHP_HRTIMERS_PREPARE,
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 0f870ba43942..6c2043509fb5 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1816,22 +1816,13 @@ static void drain_all_stock(struct mem_cgroup 
*root_memcg)
        mutex_unlock(&percpu_charge_mutex);
 }
 
-static int memcg_cpu_hotplug_callback(struct notifier_block *nb,
-                                       unsigned long action,
-                                       void *hcpu)
+static int memcg_hotplug_cpu_dead(unsigned int cpu)
 {
-       int cpu = (unsigned long)hcpu;
        struct memcg_stock_pcp *stock;
 
-       if (action == CPU_ONLINE)
-               return NOTIFY_OK;
-
-       if (action != CPU_DEAD && action != CPU_DEAD_FROZEN)
-               return NOTIFY_OK;
-
        stock = &per_cpu(memcg_stock, cpu);
        drain_stock(stock);
-       return NOTIFY_OK;
+       return 0;
 }
 
 static void reclaim_high(struct mem_cgroup *memcg,
@@ -5774,16 +5765,17 @@ __setup("cgroup.memory=", cgroup_memory);
 /*
  * subsys_initcall() for memory controller.
  *
- * Some parts like hotcpu_notifier() have to be initialized from this context
- * because of lock dependencies (cgroup_lock -> cpu hotplug) but basically
- * everything that doesn't depend on a specific mem_cgroup structure should
- * be initialized from here.
+ * Some parts like memcg_hotplug_cpu_dead() have to be initialized from this
+ * context because of lock dependencies (cgroup_lock -> cpu hotplug) but
+ * basically everything that doesn't depend on a specific mem_cgroup structure
+ * should be initialized from here.
  */
 static int __init mem_cgroup_init(void)
 {
        int cpu, node;
 
-       hotcpu_notifier(memcg_cpu_hotplug_callback, 0);
+       cpuhp_setup_state_nocalls(CPUHP_MM_MEMCQ_DEAD, "mm/memctrl:dead", NULL,
+                                 memcg_hotplug_cpu_dead);
 
        for_each_possible_cpu(cpu)
                INIT_WORK(&per_cpu_ptr(&memcg_stock, cpu)->work,
-- 
2.10.2

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