diff --git a/lib/iov_iter.c b/lib/iov_iter.c
index ae82d9cea5533647181cea7b6c3d005838bfc0f8..f835964c9485f147699609bf2c2dc1ffecb8833b 100644
--- a/lib/iov_iter.c
+++ b/lib/iov_iter.c
@@ -790,6 +790,8 @@ void iov_iter_revert(struct iov_iter *i, size_t unroll)
 {
 	if (!unroll)
 		return;
+	if (WARN_ON(unroll > MAX_RW_COUNT))
+		return;
 	i->count += unroll;
 	if (unlikely(i->type & ITER_PIPE)) {
 		struct pipe_inode_info *pipe = i->pipe;
diff --git a/mm/filemap.c b/mm/filemap.c
index b7b973b47d8d9c498d9cafc83bfa2a21ea33e757..6f1be573a5e60fbb0c4a6cbcf85df9b32b0fc673 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -2050,7 +2050,7 @@ generic_file_read_iter(struct kiocb *iocb, struct iov_iter *iter)
 			iocb->ki_pos += retval;
 			count -= retval;
 		}
-		iov_iter_revert(iter, iov_iter_count(iter) - count);
+		iov_iter_revert(iter, count - iov_iter_count(iter));
 
 		/*
 		 * Btrfs can have a short DIO read if we encounter