FOLL_DUMP
if ((gup_flags & FOLL_DUMP) || !is_zero_pfn(pte_pfn(entry)))
FOLL_FORCE | FOLL_DUMP | FOLL_GET);
if (!(flags & FOLL_DUMP))
if ((flags & FOLL_DUMP) && is_huge_zero_pmd(pmdval))
if (flags & FOLL_DUMP) {