Index: user/pho/stress2/misc/forkbomb.sh
===================================================================
--- user/pho/stress2/misc/forkbomb.sh	(revision 297384)
+++ user/pho/stress2/misc/forkbomb.sh	(revision 297385)
@@ -1,134 +1,148 @@
 #!/bin/sh
 
 #
 # Copyright (c) 2015 EMC Corp.
 # All rights reserved.
 #
 # Redistribution and use in source and binary forms, with or without
 # modification, are permitted provided that the following conditions
 # are met:
 # 1. Redistributions of source code must retain the above copyright
 #    notice, this list of conditions and the following disclaimer.
 # 2. Redistributions in binary form must reproduce the above copyright
 #    notice, this list of conditions and the following disclaimer in the
 #    documentation and/or other materials provided with the distribution.
 #
 # THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 # ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 # IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 # ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 # FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 # DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 # OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 # HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 # LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 # OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 # SUCH DAMAGE.
 #
 # $FreeBSD$
 #
 
 # Fork bomb memory leak test scenario.
 # https://en.wikipedia.org/wiki/Fork_bomb
 
 # OO memory seen:
 # https://people.freebsd.org/~pho/stress/log/forkbomb.txt
 # Fixed by r289026.
 
 . ../default.cfg
 [ `id -u ` -ne 0 ] && echo "Must be root!" && exit 1
 
 dir=/tmp
 odir=`pwd`
 cd $dir
 sed '1,/^EOF/d' < $odir/$0 > $dir/forkbomb.c
 mycc -o forkbomb -Wall -Wextra -O0 -g forkbomb.c || exit 1
 rm -f forkbomb.c
 cd $odir
 
 mount | grep "on $mntpoint " | grep -q /dev/md && umount -f $mntpoint
 mdconfig -l | grep -q md$mdstart &&  mdconfig -d -u $mdstart
 mdconfig -a -t swap -s 512m -u $mdstart || exit 1
 bsdlabel -w md$mdstart auto
 newfs $newfs_flags md${mdstart}$part > /dev/null
 mount /dev/md${mdstart}$part $mntpoint
 
-sysctl kern.maxproc
-vmstat -z | sed -n "1p;/PROC/p;/THREAD/p"
-echo
+su $testuser -c /tmp/forkbomb
 
-/tmp/forkbomb
-
-vmstat -z | sed -n "/PROC/p;/THREAD/p"
-
 while mount | grep "on $mntpoint " | grep -q /dev/md; do
 	umount $mntpoint || sleep 1
 done
 mdconfig -d -u $mdstart
 rm -rf /tmp/forkbomb
-exit
+exit 0
 
 EOF
 #include <sys/param.h>
 #include <sys/mman.h>
 
 #include <machine/atomic.h>
 
 #include <err.h>
 #include <errno.h>
 #include <fcntl.h>
 #include <signal.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <unistd.h>
 
 volatile u_int *share;
 
-#define R1 0
-#define R2 1
+#define R1 1 /* sync start  */
+#define R2 2 /* forks       */
+#define R3 3 /* exits       */
+#define R4 4 /* fork failed */
 
+//#define DEBUG
 #define MXFAIL 100
+#define MAXPROC 40000	/* Arbitrary cap */
 #define PARALLEL 200
 
 void
 test(void)
 {
 	int r;
 
 	atomic_add_int(&share[R1], 1);
 	while (share[R1] != PARALLEL)
 		;
+	atomic_add_int(&share[R2], 1);
 
 	for (;;) {
-		r = fork();
-		if (r == -1)
-			atomic_add_int(&share[R2], 1);
-		if (share[R2] > MXFAIL)
+		if (share[R2] >= MAXPROC || share[R4] > MXFAIL)
 			break;
+		atomic_add_int(&share[R2], 1);
+		if ((r = fork()) == -1) {
+			atomic_add_int(&share[R4], 1);
+			atomic_add_int(&share[R2], -1);
+			break;
+		}
 	}
 
+	atomic_add_int(&share[R3], 1);
 	_exit(0);
 }
 
 int
 main(void)
 {
+	struct sigaction sa;
 	size_t len;
 	int i;
 
-	len = getpagesize();
-	if ((share = mmap(NULL, len, PROT_READ | PROT_WRITE, MAP_ANON | MAP_SHARED,
-	    -1, 0)) == MAP_FAILED)
+	len = PAGE_SIZE;
+	if ((share = mmap(NULL, len, PROT_READ | PROT_WRITE,
+	    MAP_ANON | MAP_SHARED, -1, 0)) == MAP_FAILED)
 		err(1, "mmap");
 
-	signal(SIGCHLD, SIG_IGN);
+	sa.sa_handler = SIG_IGN;
+	sigemptyset(&sa.sa_mask);
+	sa.sa_flags = 0;
+	if (sigaction(SIGCHLD, &sa, 0) == -1)
+		err(1, "sigaction");
+
 	for (i = 0; i < PARALLEL; i++) {
 		if (fork() == 0)
 			test();
 	}
 
-	while (share[R2] < MXFAIL)
+	while (share[R2] == 0 || share[R3] < share[R2])
 		sleep(1);
+
+#if defined(DEBUG)
+	fprintf(stderr, "MAXPROC: %d. forks: %u / exits: %u / fails: %u\n",
+	    MAXPROC, share[R2], share[R3], share[R4]);
+#endif
 
 	return (0);
 }