diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 789b84f..688eb0c 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -5063,6 +5063,7 @@
 	memset(css, 0, sizeof(*css));
 	css->cgroup = cgrp;
 	css->ss = ss;
+	css->id = -1;
 	INIT_LIST_HEAD(&css->sibling);
 	INIT_LIST_HEAD(&css->children);
 	css->serial_nr = css_serial_nr_next++;