+int set_online_page_callback(online_page_callback_t callback)
+{
+ int rc = -EINVAL;
+
+ lock_memory_hotplug();
+
+ if (online_page_callback == generic_online_page) {
+ online_page_callback = callback;
+ rc = 0;
+ }
+
+ unlock_memory_hotplug();
+
+ return rc;
+}
+EXPORT_SYMBOL_GPL(set_online_page_callback);
+
+int restore_online_page_callback(online_page_callback_t callback)
+{
+ int rc = -EINVAL;
+
+ lock_memory_hotplug();
+
+ if (online_page_callback == callback) {
+ online_page_callback = generic_online_page;
+ rc = 0;
+ }
+
+ unlock_memory_hotplug();
+
+ return rc;
+}
+EXPORT_SYMBOL_GPL(restore_online_page_callback);
+
+void __online_page_set_limits(struct page *page)