diff --git a/kernel/pid.c b/kernel/pid.c
index f633a7d..1a95235 100644
--- a/kernel/pid.c
+++ b/kernel/pid.c
@@ -300,7 +300,7 @@ void free_pid(struct pid *pid)
 	unsigned long flags;
 
 	spin_lock_irqsave(&pidmap_lock, flags);
-	for (i = 0; i <= pid->level; i++) {
+	for (i = pid->level; i >= 0; i--) {
 		struct upid *upid = pid->numbers + i;
 		struct pid_namespace *ns = upid->ns;
 		if (!hlist_unhashed(&upid->pid_chain))
@@ -323,6 +323,8 @@ void free_pid(struct pid *pid)
 			schedule_work(&ns->proc_work);
 			break;
 		}
+		if (ns->flags & PID_NS_HIDDEN)
+			break;
 	}
 	spin_unlock_irqrestore(&pidmap_lock, flags);
 	ub_kmem_uncharge(pid->ub,