PG_DIRECT_MAP_4K
update_page_count(PG_DIRECT_MAP_4K, pages);
update_page_count(PG_DIRECT_MAP_4K, PTRS_PER_PTE);
atomic_long_read(&direct_pages_count[PG_DIRECT_MAP_4K]) << 2);
update_page_count(PG_DIRECT_MAP_4K, add ? pages : -pages);