+#if defined(CONFIG_NUMA) && defined(CONFIG_MEMORY_HOTPLUG)
+/*
+ * Drains freelist for a node on each slab cache, used for memory hot-remove.
+ * Returns -EBUSY if all objects cannot be drained so that the node is not
+ * removed.
+ *
+ * Must hold cache_chain_mutex.
+ */
+static int __meminit drain_cache_nodelists_node(int node)
+{
+ struct kmem_cache *cachep;
+ int ret = 0;
+
+ list_for_each_entry(cachep, &cache_chain, next) {
+ struct kmem_list3 *l3;
+
+ l3 = cachep->nodelists[node];
+ if (!l3)
+ continue;
+
+ drain_freelist(cachep, l3, l3->free_objects);
+
+ if (!list_empty(&l3->slabs_full) ||
+ !list_empty(&l3->slabs_partial)) {
+ ret = -EBUSY;
+ break;
+ }
+ }
+ return ret;
+}
+
+static int __meminit slab_memory_callback(struct notifier_block *self,
+ unsigned long action, void *arg)
+{
+ struct memory_notify *mnb = arg;
+ int ret = 0;
+ int nid;
+
+ nid = mnb->status_change_nid;
+ if (nid < 0)
+ goto out;
+
+ switch (action) {
+ case MEM_GOING_ONLINE:
+ mutex_lock(&cache_chain_mutex);
+ ret = init_cache_nodelists_node(nid);
+ mutex_unlock(&cache_chain_mutex);
+ break;
+ case MEM_GOING_OFFLINE:
+ mutex_lock(&cache_chain_mutex);
+ ret = drain_cache_nodelists_node(nid);
+ mutex_unlock(&cache_chain_mutex);
+ break;
+ case MEM_ONLINE:
+ case MEM_OFFLINE:
+ case MEM_CANCEL_ONLINE:
+ case MEM_CANCEL_OFFLINE:
+ break;
+ }
+out:
+ return ret ? notifier_from_errno(ret) : NOTIFY_OK;
+}
+#endif /* CONFIG_NUMA && CONFIG_MEMORY_HOTPLUG */
+