Index: sys/vm/vm_pageout.c
===================================================================
--- sys/vm/vm_pageout.c
+++ sys/vm/vm_pageout.c
@@ -1743,11 +1743,11 @@
 void
 vm_pageout_oom(int shortage)
 {
-	struct proc *p, *bigproc;
+	struct proc *p, *pp, *bigproc;
 	vm_offset_t size, bigsize;
 	struct thread *td;
 	struct vmspace *vm;
-	int now;
+	int now, wokeup;
 	bool breakout;
 
 	/*
@@ -1781,11 +1781,25 @@
 	 */
 	bigproc = NULL;
 	bigsize = 0;
+	wokeup = 0;
 	sx_slock(&allproc_lock);
 	FOREACH_PROC_IN_SYSTEM(p) {
 		PROC_LOCK(p);
 
 		/*
+		 * If we find a zombie or killed process, fault in its parent to
+		 * give a chance to collect the child exit status and cleanup.
+		 */
+		if ((p->p_state == PRS_ZOMBIE) || P_KILLED(p)) {
+			pp = p->p_pptr;
+			PROC_UNLOCK(p);
+			PROC_LOCK(pp);
+			faultin(pp);
+			PROC_UNLOCK(pp);
+			wokeup++;
+			continue;
+		}
+		/*
 		 * If this is a system, protected or killed process, skip it.
 		 */
 		if (p->p_state != PRS_NORMAL || (p->p_flag & (P_INEXEC |
@@ -1855,6 +1869,14 @@
 		}
 	}
 	sx_sunlock(&allproc_lock);
+	/*
+	 * If wake up calls are sent, defer killing another process.
+	 */
+	if (wokeup > 0) {
+		_PRELE(bigproc);
+		return;
+	}
+
 	if (bigproc != NULL) {
 		if (vm_panic_on_oom != 0)
 			panic("out of swap space");