diff --git a/mm/filemap.c b/mm/filemap.c
index ca389394fa2a1d563097c06d34881ac0e8e42559..1a3dd5914726d4cc06f8f30e9d2594c176c361be 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -837,9 +837,6 @@ unsigned find_get_pages_contig(struct address_space *mapping, pgoff_t index,
 		if (radix_tree_deref_retry(page))
 			goto restart;
 
-		if (page->mapping == NULL || page->index != index)
-			break;
-
 		if (!page_cache_get_speculative(page))
 			goto repeat;
 
@@ -849,6 +846,16 @@ unsigned find_get_pages_contig(struct address_space *mapping, pgoff_t index,
 			goto repeat;
 		}
 
+		/*
+		 * must check mapping and index after taking the ref.
+		 * otherwise we can get both false positives and false
+		 * negatives, which is just confusing to the caller.
+		 */
+		if (page->mapping == NULL || page->index != index) {
+			page_cache_release(page);
+			break;
+		}
+
 		pages[ret] = page;
 		ret++;
 		index++;