--- zzzz-none-000/linux-4.4.60/kernel/pid.c	2017-04-08 07:53:53.000000000 +0000
+++ dragonfly-4020-701/linux-4.4.60/kernel/pid.c	2018-11-08 13:36:17.000000000 +0000
@@ -431,6 +431,7 @@
 	new->pids[type].pid = old->pids[type].pid;
 	hlist_replace_rcu(&old->pids[type].node, &new->pids[type].node);
 }
+EXPORT_SYMBOL(find_task_by_vpid);
 
 struct task_struct *pid_task(struct pid *pid, enum pid_type type)
 {