* This function preforms the balloon page migration task.
* Called through balloon_mapping->a_ops->migratepage
*/
-int virtballoon_migratepage(struct address_space *mapping,
+static int virtballoon_migratepage(struct address_space *mapping,
struct page *newpage, struct page *page, enum migrate_mode mode)
{
struct balloon_dev_info *vb_dev_info = balloon_page_device(page);