page->private = (unsigned long)&pgd_list;
set_page_private(page, (unsigned long)&pgd_list);
static inline void pgd_list_add(pgd_t *pgd){	struct page *page = virt_to_page(pgd);	page->index = (unsigned long)pgd_list;	if (pgd_list)		pgd_list->private = (unsigned long)&page->index;	pgd_list = page;	page->private = (unsigned long)&pgd_list;}