Index: user/pho/stress2/misc/mountu.sh
===================================================================
--- user/pho/stress2/misc/mountu.sh	(revision 285195)
+++ user/pho/stress2/misc/mountu.sh	(revision 285196)
@@ -1,166 +1,170 @@
 #!/bin/sh
 
 #
 # Copyright (c) 2012 Peter Holm <pho@FreeBSD.org>
 # 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.
 #
 # $FreeBSD$
 #
 
 # Change mount point from rw to ro with a file mapped rw
 # Currently fails for NFS
 
+# Page fault seen:
+# https://people.freebsd.org/~pho/stress/log/mountu.txt
+# Fixed by: r285039.
+
 [ `id -u ` -ne 0 ] && echo "Must be root!" && exit 1
 
 . ../default.cfg
 
 here=`pwd`
 cd /tmp
 sed '1,/^EOF/d' < $here/$0 > mountu.c
 mycc -o mountu -Wall -Wextra -O2 mountu.c
 rm -f mountu.c
 
 pstat() {
 	pid=`ps a | grep -v grep | grep /tmp/mountu | awk '{print $1}'`
 	[ -n "$pid" ] && procstat -v $pid
 }
 
 mount | grep -q "$mntpoint " && umount $mntpoint
 mdconfig -l | grep -q $mdstart &&  mdconfig -d -u $mdstart
 mdconfig -a -t swap -s 100m -u $mdstart
 bsdlabel -w md${mdstart} auto
 newfs $newfs_flags md${mdstart}${part} > /dev/null
 mount /dev/md${mdstart}${part} $mntpoint
 chmod 777 $mntpoint
 
 /tmp/mountu $mntpoint/file &
 
 sleep 1
 if ! mount -u -o ro $mntpoint 2>&1 | grep -q "Device busy"; then
 	echo "UFS FAILED"
 	pstat
 fi
 wait
 while mount | grep -q "$mntpoint "; do
 	umount $mntpoint || sleep 1
 done
 
 mdconfig -d -u $mdstart
 
 if ping -c 2 `echo $nfs_export | sed 's/:.*//'` > /dev/null 2>&1; then
 	mount -t nfs -o tcp -o retrycnt=3 -o intr -o soft -o rw $nfs_export \
 	    $mntpoint
 	rm -f /tmp/file
 	/tmp/mountu $mntpoint/file &
 	sleep 1
 
 	if ! mount -u -o ro $mntpoint 2>&1 | grep -q "Device busy"; then
 		echo "NFS FAILED"
 	fi
 	wait
 	umount $mntpoint
 fi
 
 if [ -x /sbin/mount_msdosfs ]; then
 	mdconfig -a -t swap -s 100m -u $mdstart
 	bsdlabel -w md${mdstart} auto
 	newfs_msdos -F 16 -b 8192 /dev/md${mdstart}$part > /dev/null 2>&1
 	mount_msdosfs -m 777 /dev/md${mdstart}$part $mntpoint
 	/tmp/mountu $mntpoint/file &
 
 	sleep 1
 	if ! mount -u -o ro $mntpoint 2>&1 | grep -q "Device busy"; then
 		echo "MSDOS FAILED"
 	fi
 	wait
 
 	while mount | grep -q "$mntpoint "; do
 		umount $mntpoint || sleep 1
 	done
 fi
 rm -f /tmp/mountu /tmp/file
 exit 0
 EOF
 #include <sys/types.h>
 #include <err.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <unistd.h>
 #include <fcntl.h>
 #include <pwd.h>
 #include <sys/mman.h>
 #include <sys/param.h>
 #include <string.h>
 #include <unistd.h>
 #include <errno.h>
 
 #define STARTADDR 0x0U
 #define ADRSPACE  0x0640000U
 
 int
 main(int argc __unused, char **argv)
 {
 	int fd, ps;
 	void *p;
 	size_t len;
 	struct passwd *pw;
 	char *c, *path;
 
 	if ((pw = getpwnam("nobody")) == NULL)
 		err(1, "no such user: nobody");
 
 	if (setgroups(1, &pw->pw_gid) ||
 	    setegid(pw->pw_gid) || setgid(pw->pw_gid) ||
 	    seteuid(pw->pw_uid) || setuid(pw->pw_uid))
 		err(1, "Can't drop privileges to \"nobody\"");
 	endpwent();
 
 	p = (void *)STARTADDR;
 	len = ADRSPACE;
 
 	path = argv[1];
 	if ((fd = open(path, O_CREAT | O_TRUNC | O_RDWR, 0622)) == -1)
 		err(1,"open(%s)", path);
 	if (ftruncate(fd, len) == -1)
 		err(1, "ftruncate");
 	if ((p = mmap(p, len, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0)) ==
 			MAP_FAILED) {
 		if (errno == ENOMEM) {
 			warn("mmap()");
 			return (1);
 		}
 		err(1, "mmap(1)");
 	}
 
 	c = p;
 	ps = getpagesize();
 	for (c = p; (void *)c < p + len; c += ps) {
 		*c = 1;
 	}
 
 	close(fd);
 	sleep(5);
 
 	return (0);
 }