generic_online_page
generic_online_page(pg, 0);
generic_online_page(pg, order);
generic_online_page(page, order);
generic_online_page(pfn_to_page(PFN_DOWN(addr)), order);
generic_online_page(page, order);
extern void generic_online_page(struct page *page, unsigned int order);
static online_page_callback_t online_page_callback = generic_online_page;
if (online_page_callback == generic_online_page) {
online_page_callback = generic_online_page;
EXPORT_SYMBOL_GPL(generic_online_page);