diff --git a/lib/iov_iter.c b/lib/iov_iter.c
index 60abc44385b795de7449b3810e9e294b7d2c48fc..fc9fb29d00eba257c99fa63de7c990a80bf075a4 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 cc480c07c71bad5b838e26f194e1d5b3e466e00f..d6e67be1802ef5290a3d49ebbc8464eaf0353a90 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -2048,7 +2048,7 @@ 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