diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 271e443..716465a 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -3789,6 +3789,11 @@
 {
 	return NULL;
 }
+
+int huge_pmd_unshare(struct mm_struct *mm, unsigned long *addr, pte_t *ptep)
+{
+	return 0;
+}
 #define want_pmd_share()	(0)
 #endif /* CONFIG_ARCH_WANT_HUGE_PMD_SHARE */