ZONES_MASK 737 include/linux/mm.h return (page->flags >> ZONES_PGSHIFT) & ZONES_MASK; ZONES_MASK 908 include/linux/mm.h page->flags &= ~(ZONES_MASK << ZONES_PGSHIFT); ZONES_MASK 909 include/linux/mm.h page->flags |= (zone & ZONES_MASK) << ZONES_PGSHIFT;