+
+static int shutdown_memcg_caches(struct kmem_cache *s,
+ struct list_head *release, bool *need_rcu_barrier)
+{
+ struct memcg_cache_array *arr;
+ struct kmem_cache *c, *c2;
+ LIST_HEAD(busy);
+ int i;
+
+ BUG_ON(!is_root_cache(s));
+
+ /*
+ * First, shutdown active caches, i.e. caches that belong to online
+ * memory cgroups.
+ */
+ arr = rcu_dereference_protected(s->memcg_params.memcg_caches,
+ lockdep_is_held(&slab_mutex));
+ for_each_memcg_cache_index(i) {
+ c = arr->entries[i];
+ if (!c)
+ continue;
+ if (__shutdown_memcg_cache(c, release, need_rcu_barrier))
+ /*
+ * The cache still has objects. Move it to a temporary
+ * list so as not to try to destroy it for a second
+ * time while iterating over inactive caches below.
+ */
+ list_move(&c->memcg_params.list, &busy);
+ else
+ /*
+ * The cache is empty and will be destroyed soon. Clear
+ * the pointer to it in the memcg_caches array so that
+ * it will never be accessed even if the root cache
+ * stays alive.
+ */
+ arr->entries[i] = NULL;
+ }
+
+ /*
+ * Second, shutdown all caches left from memory cgroups that are now
+ * offline.
+ */
+ list_for_each_entry_safe(c, c2, &s->memcg_params.list,
+ memcg_params.list)
+ __shutdown_memcg_cache(c, release, need_rcu_barrier);
+
+ list_splice(&busy, &s->memcg_params.list);
+
+ /*
+ * A cache being destroyed must be empty. In particular, this means
+ * that all per memcg caches attached to it must be empty too.
+ */
+ if (!list_empty(&s->memcg_params.list))
+ return -EBUSY;
+ return 0;
+}
+#else
+static inline int shutdown_memcg_caches(struct kmem_cache *s,
+ struct list_head *release, bool *need_rcu_barrier)
+{
+ return 0;
+}