Index: sys/kern/kern_exit.c
===================================================================
RCS file: /cvsroot/src/sys/kern/kern_exit.c,v
retrieving revision 1.293
diff -p -u -r1.293 kern_exit.c
--- sys/kern/kern_exit.c	5 Dec 2021 08:13:12 -0000	1.293
+++ sys/kern/kern_exit.c	16 Apr 2022 04:51:10 -0000
@@ -631,6 +631,17 @@ retry:
 			continue;
 		lwp_lock(l2);
 		l2->l_flag |= LW_WEXIT;
+		/*
+		 * Wake up sibling threads that are blocked for a
+		 * vforked child so that the process can exit.
+		 */
+		if (l2->l_vforkwaiting) {
+printf("exit_lwps: pid=%d lwp=%p waking lwp=%p\n", p->p_pid, l, l2);
+			mutex_enter(&proc_lock);
+			l2->l_vforkwaiting = false;
+			cv_broadcast(&l2->l_waitcv);
+			mutex_exit(&proc_lock);
+		}
 		if ((l2->l_stat == LSSLEEP && (l2->l_flag & LW_SINTR)) ||
 		    l2->l_stat == LSSUSPENDED || l2->l_stat == LSSTOP) {
 			l2->l_flag &= ~LW_DBGSUSPEND;