PM_PFRAME_BITS   1261 fs/proc/task_mmu.c #define PM_PFRAME_MASK		GENMASK_ULL(PM_PFRAME_BITS - 1, 0)
PM_PFRAME_BITS     50 tools/vm/page-types.c #define PM_PFRAME_MASK		((1LL << PM_PFRAME_BITS) - 1)