drm/nouveau: warn when trying to free mm which is still in use

Signed-off-by: Marcin Slusarz <marcin.slusarz@gmail.com>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

drivers/gpu/drm/nouveau/core/core/mm.c

@@ -236,7 +236,7 @@ nouveau_mm_fini(struct nouveau_mm *mm)
 	int nodes = 0;
 
 	list_for_each_entry(node, &mm->nodes, nl_entry) {
-		if (nodes++ == mm->heap_nodes)
+		if (WARN_ON(nodes++ == mm->heap_nodes))
 			return -EBUSY;
 	}