/* Default handling if a filesystem does not provide a migration function.  */
static int fallback_migrate_page(struct address_space *mapping, struct page *newpage, struct page *page)
/* Default handling if a filesystem does not provide a migration function.  */
static int fallback_migrate_page(struct address_space *mapping, struct page *newpage, struct page *page)
{
	if (PageDirty(page))
		return writeout(mapping, page);
	if (page_has_private(page) &&
	    !try_to_release_page(page, GFP_KERNEL))
		return -EAGAIN;
	return migrate_page(mapping, newpage, page);
}