linux-master/mm/gup.c

785 	pmd_t pmdval = *pmd;
791 	page = pmd_page(pmdval);
793 	    !can_follow_write_pmd(pmdval, page, vma, flags))
797 	if ((flags & FOLL_DUMP) && is_huge_zero_pmd(pmdval))
803 	if (!pmd_write(pmdval) && gup_must_unshare(vma, flags, page))
814 	if (pmd_trans_huge(pmdval) && (flags & FOLL_TOUCH))
1017 	pmd_t *pmd, pmdval;
1023 	pmdval = pmdp_get_lockless(pmd);
1024 	if (pmd_none(pmdval))
1026 	if (!pmd_present(pmdval))
1028 	if (unlikely(is_hugepd(__hugepd(pmd_val(pmdval)))))
1029 		return follow_hugepd(vma, __hugepd(pmd_val(pmdval)),
1031 	if (pmd_devmap(pmdval)) {
1039 	if (likely(!pmd_leaf(pmdval)))
1042 	if (pmd_protnone(pmdval) && !gup_can_follow_protnone(vma, flags))
1046 	pmdval = *pmd;
1047 	if (unlikely(!pmd_present(pmdval))) {
1051 	if (unlikely(!pmd_leaf(pmdval))) {
1055 	if (pmd_trans_huge(pmdval) && (flags & FOLL_SPLIT_PMD)) {