diff --git a/mm/filemap.c b/mm/filemap.c
index 61ba5e405791918e2bab077144300b1d4d7ab6ce..4ee2e998e937dc4731ce5d2d4af82119d8077ea9 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1029,6 +1029,9 @@ static void do_generic_file_read(struct file *filp, loff_t *ppos,
 				goto page_not_up_to_date;
 			if (!trylock_page(page))
 				goto page_not_up_to_date;
+			/* Did it get truncated before we got the lock? */
+			if (!page->mapping)
+				goto page_not_up_to_date_locked;
 			if (!mapping->a_ops->is_partially_uptodate(page,
 								desc, offset))
 				goto page_not_up_to_date_locked;