1 files changed, 22 insertions, 17 deletions

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 0f870ba43942..175ec51c346d 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,
@@ -2154,6 +2145,8 @@ struct memcg_kmem_cache_create_work {
 	struct work_struct work;
 };
 
+static struct workqueue_struct *memcg_kmem_cache_create_wq;
+
 static void memcg_kmem_cache_create_func(struct work_struct *w)
 {
 	struct memcg_kmem_cache_create_work *cw =
@@ -2185,7 +2178,7 @@ static void __memcg_schedule_kmem_cache_create(struct mem_cgroup *memcg,
 	cw->cachep = cachep;
 	INIT_WORK(&cw->work, memcg_kmem_cache_create_func);
 
-	schedule_work(&cw->work);
+	queue_work(memcg_kmem_cache_create_wq, &cw->work);
 }
 
 static void memcg_schedule_kmem_cache_create(struct mem_cgroup *memcg,
@@ -5774,16 +5767,28 @@ __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);
+#ifndef CONFIG_SLOB
+	/*
+	 * Kmem cache creation is mostly done with the slab_mutex held,
+	 * so use a special workqueue to avoid stalling all worker
+	 * threads in case lots of cgroups are created simultaneously.
+	 */
+	memcg_kmem_cache_create_wq =
+		alloc_ordered_workqueue("memcg_kmem_cache_create", 0);
+	BUG_ON(!memcg_kmem_cache_create_wq);
+#endif
+
+	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,