diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index cf8ba26b7c6ec23e7eb7337192ff3e54b5ec81a0..ebe7ce49f4b73924b716d0b6326ebc1b295a6917 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -80,6 +80,14 @@ struct cgroup_subsys_state {
 
 	unsigned int flags;
 
+	/*
+	 * Monotonically increasing unique serial number which defines a
+	 * uniform order among all csses.  It's guaranteed that all
+	 * ->children lists are in the ascending order of ->serial_nr and
+	 * used to allow interrupting and resuming iterations.
+	 */
+	u64 serial_nr;
+
 	/* percpu_ref killing and RCU release */
 	struct rcu_head rcu_head;
 	struct work_struct destroy_work;
@@ -178,14 +186,6 @@ struct cgroup {
 	struct kernfs_node *kn;		/* cgroup kernfs entry */
 	struct kernfs_node *populated_kn; /* kn for "cgroup.subtree_populated" */
 
-	/*
-	 * Monotonically increasing unique serial number which defines a
-	 * uniform order among all cgroups.  It's guaranteed that all
-	 * ->children lists are in the ascending order of ->serial_nr.
-	 * It's used to allow interrupting and resuming iterations.
-	 */
-	u64 serial_nr;
-
 	/* the bitmask of subsystems enabled on the child cgroups */
 	unsigned int child_subsys_mask;
 
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index dcb06e181ce4f6178a02bd82e3bc6d898faf533b..d5af128ec1ecb3d6cd4927fa91576b1206d8f4cc 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -157,14 +157,13 @@ static int cgroup_root_count;
 static DEFINE_IDR(cgroup_hierarchy_idr);
 
 /*
- * Assign a monotonically increasing serial number to cgroups.  It
- * guarantees cgroups with bigger numbers are newer than those with smaller
- * numbers.  Also, as cgroups are always appended to the parent's
- * ->children list, it guarantees that sibling cgroups are always sorted in
- * the ascending serial number order on the list.  Protected by
- * cgroup_mutex.
+ * Assign a monotonically increasing serial number to csses.  It guarantees
+ * cgroups with bigger numbers are newer than those with smaller numbers.
+ * Also, as csses are always appended to the parent's ->children list, it
+ * guarantees that sibling csses are always sorted in the ascending serial
+ * number order on the list.  Protected by cgroup_mutex.
  */
-static u64 cgroup_serial_nr_next = 1;
+static u64 css_serial_nr_next = 1;
 
 /* This flag indicates whether tasks in the fork and exit paths should
  * check for fork/exit handlers to call. This avoids us having to do
@@ -3133,7 +3132,7 @@ css_next_child(struct cgroup_subsys_state *pos_css,
 		next = list_entry_rcu(pos->self.sibling.next, struct cgroup, self.sibling);
 	} else {
 		list_for_each_entry_rcu(next, &cgrp->self.children, self.sibling)
-			if (next->serial_nr > pos->serial_nr)
+			if (next->self.serial_nr > pos->self.serial_nr)
 				break;
 	}
 
@@ -4168,6 +4167,8 @@ static void css_release(struct percpu_ref *ref)
 static void init_and_link_css(struct cgroup_subsys_state *css,
 			      struct cgroup_subsys *ss, struct cgroup *cgrp)
 {
+	lockdep_assert_held(&cgroup_mutex);
+
 	cgroup_get(cgrp);
 
 	memset(css, 0, sizeof(*css));
@@ -4175,6 +4176,7 @@ static void init_and_link_css(struct cgroup_subsys_state *css,
 	css->ss = ss;
 	INIT_LIST_HEAD(&css->sibling);
 	INIT_LIST_HEAD(&css->children);
+	css->serial_nr = css_serial_nr_next++;
 
 	if (cgroup_parent(cgrp)) {
 		css->parent = cgroup_css(cgroup_parent(cgrp), ss);
@@ -4348,7 +4350,7 @@ static int cgroup_mkdir(struct kernfs_node *parent_kn, const char *name,
 	 */
 	kernfs_get(kn);
 
-	cgrp->serial_nr = cgroup_serial_nr_next++;
+	cgrp->self.serial_nr = css_serial_nr_next++;
 
 	/* allocation complete, commit to creation */
 	list_add_tail_rcu(&cgrp->self.sibling, &cgroup_parent(cgrp)->self.children);