diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 5d7601b..f4daef4 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -1973,12 +1973,15 @@ retry_avoidcopy:
 		 */
 		if (outside_reserve) {
 			BUG_ON(huge_pte_none(pte));
+			spin_unlock(&mm->page_table_lock);
 			if (unmap_ref_private(mm, vma, old_page, address)) {
+				spin_lock(&mm->page_table_lock);
 				BUG_ON(page_count(old_page) != 1);
 				BUG_ON(huge_pte_none(pte));
 				goto retry_avoidcopy;
 			}
 			WARN_ON_ONCE(1);
+			spin_lock(&mm->page_table_lock);
 		}
 
 		return -PTR_ERR(new_page);