+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+/*
+ * Check that @page is mapped at @address into @mm. In contrast to
+ * page_check_address(), this function can handle transparent huge pages.
+ *
+ * On success returns true with pte mapped and locked. For PMD-mapped
+ * transparent huge pages *@ptep is set to NULL.
+ */
+bool page_check_address_transhuge(struct page *page, struct mm_struct *mm,
+ unsigned long address, pmd_t **pmdp,
+ pte_t **ptep, spinlock_t **ptlp)
+{
+ pgd_t *pgd;
+ pud_t *pud;
+ pmd_t *pmd;
+ pte_t *pte;
+ spinlock_t *ptl;
+
+ if (unlikely(PageHuge(page))) {
+ /* when pud is not present, pte will be NULL */
+ pte = huge_pte_offset(mm, address);
+ if (!pte)
+ return false;
+
+ ptl = huge_pte_lockptr(page_hstate(page), mm, pte);
+ pmd = NULL;
+ goto check_pte;
+ }
+
+ pgd = pgd_offset(mm, address);
+ if (!pgd_present(*pgd))
+ return false;
+ pud = pud_offset(pgd, address);
+ if (!pud_present(*pud))
+ return false;
+ pmd = pmd_offset(pud, address);
+
+ if (pmd_trans_huge(*pmd)) {
+ ptl = pmd_lock(mm, pmd);
+ if (!pmd_present(*pmd))
+ goto unlock_pmd;
+ if (unlikely(!pmd_trans_huge(*pmd))) {
+ spin_unlock(ptl);
+ goto map_pte;
+ }
+
+ if (pmd_page(*pmd) != page)
+ goto unlock_pmd;
+
+ pte = NULL;
+ goto found;
+unlock_pmd:
+ spin_unlock(ptl);
+ return false;
+ } else {
+ pmd_t pmde = *pmd;
+
+ barrier();
+ if (!pmd_present(pmde) || pmd_trans_huge(pmde))
+ return false;
+ }
+map_pte:
+ pte = pte_offset_map(pmd, address);
+ if (!pte_present(*pte)) {
+ pte_unmap(pte);
+ return false;
+ }
+
+ ptl = pte_lockptr(mm, pmd);
+check_pte:
+ spin_lock(ptl);
+
+ if (!pte_present(*pte)) {
+ pte_unmap_unlock(pte, ptl);
+ return false;
+ }
+
+ /* THP can be referenced by any subpage */
+ if (pte_pfn(*pte) - page_to_pfn(page) >= hpage_nr_pages(page)) {
+ pte_unmap_unlock(pte, ptl);
+ return false;
+ }
+found:
+ *ptep = pte;
+ *pmdp = pmd;
+ *ptlp = ptl;
+ return true;
+}
+#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
+