HSTATE_ATTR_RO   1212 mm/hugetlb.c   HSTATE_ATTR_RO(free_hugepages);
HSTATE_ATTR_RO   1220 mm/hugetlb.c   HSTATE_ATTR_RO(resv_hugepages);
HSTATE_ATTR_RO   1228 mm/hugetlb.c   HSTATE_ATTR_RO(surplus_hugepages);