+
+#ifdef CONFIG_HUGETLBFS
+/*
+ * Handle per node hstate attribute [un]registration on transistions
+ * to/from memoryless state.
+ */
+static void node_hugetlb_work(struct work_struct *work)
+{
+ struct node *node = container_of(work, struct node, node_work);
+
+ /*
+ * We only get here when a node transitions to/from memoryless state.
+ * We can detect which transition occurred by examining whether the
+ * node has memory now. hugetlb_register_node() already check this
+ * so we try to register the attributes. If that fails, then the
+ * node has transitioned to memoryless, try to unregister the
+ * attributes.
+ */
+ if (!hugetlb_register_node(node))
+ hugetlb_unregister_node(node);
+}
+
+static void init_node_hugetlb_work(int nid)
+{
+ INIT_WORK(&node_devices[nid].node_work, node_hugetlb_work);
+}
+
+static int node_memory_callback(struct notifier_block *self,
+ unsigned long action, void *arg)
+{
+ struct memory_notify *mnb = arg;
+ int nid = mnb->status_change_nid;
+
+ switch (action) {
+ case MEM_ONLINE:
+ case MEM_OFFLINE:
+ /*
+ * offload per node hstate [un]registration to a work thread
+ * when transitioning to/from memoryless state.
+ */
+ if (nid != NUMA_NO_NODE)
+ schedule_work(&node_devices[nid].node_work);
+ break;
+
+ case MEM_GOING_ONLINE:
+ case MEM_GOING_OFFLINE:
+ case MEM_CANCEL_ONLINE:
+ case MEM_CANCEL_OFFLINE:
+ default:
+ break;
+ }
+
+ return NOTIFY_OK;
+}
+#endif /* CONFIG_HUGETLBFS */
+#else /* !CONFIG_MEMORY_HOTPLUG_SPARSE */
+