pprev = (struct page **)page->private;
pprev = (struct page **)page_private(page);
static inline void pgd_list_del(pgd_t *pgd){	struct page *next, **pprev, *page = virt_to_page(pgd);	next = (struct page *)page->index;	pprev = (struct page **)page->private;	*pprev = next;	if (next)		next->private = (unsigned long)pprev;}