diff --git a/tools/test/stress2/misc/unionfs10.sh b/tools/test/stress2/misc/unionfs10.sh
new file mode 100755
index 000000000000..866de62d9ff0
--- /dev/null
+++ b/tools/test/stress2/misc/unionfs10.sh
@@ -0,0 +1,87 @@
+#!/bin/sh
+
+#
+# Copyright (c) 2022 Jason Harmening <jah@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.
+#
+
+[ `id -u ` -ne 0 ] && echo "Must be root!" && exit 1
+
+# Regression test:
+
+# There is an issue, namely, when the lower file is already
+# opened r/w, but its nullfs alias is executed. This situation obviously
+# shall result in ETXTBUSY, but it currently does not.
+
+# Based on nullfs10.sh by pho@, original test scenario by kib@
+
+. ../default.cfg
+
+md1=$mdstart
+md2=$((md1 + 1))
+mp1=/mnt$md1
+mp2=/mnt$md2
+mkdir -p $mp1 $mp2
+set -e
+for i in $mp1 $mp2; do
+	mount | grep -q "on $i " && umount -f $i
+done
+for i in $md1 $md2; do
+	mdconfig -l | grep -q md$i && mdconfig -d -u $i
+done
+
+mdconfig -a -t swap -s 4g -u $md1
+mdconfig -a -t swap -s 4g -u $md2
+newfs $newfs_flags -n md$md1 > /dev/null
+newfs $newfs_flags -n md$md2 > /dev/null
+mount /dev/md$md1 $mp1
+mount /dev/md$md2 $mp2
+
+mount -t unionfs -o noatime $mp1 $mp2
+set +e
+
+mount | grep -E "$mp1|$mp2"
+
+chmod 777 $mp1
+chmod 777 $mp2
+
+cp /bin/ls $mp1
+chmod +w $mp1/ls
+sleep 2 >> $mp1/ls &
+sleep .5
+
+# This line should cause a "$mp2/ls: Text file busy" error
+$mp2/ls -l /bin/ls $mp1 $mp2 && echo FAIL || echo OK
+kill $!
+wait
+
+while mount | grep -q "$mp2 "; do
+	umount $mp2 || sleep 1
+done
+
+while mount | grep -q "$mp1 "; do
+	umount $mp1 || sleep 1
+done
+mdconfig -d -u $md2
+mdconfig -d -u $md1
diff --git a/tools/test/stress2/misc/unionfs11.sh b/tools/test/stress2/misc/unionfs11.sh
new file mode 100755
index 000000000000..b86be896d8f5
--- /dev/null
+++ b/tools/test/stress2/misc/unionfs11.sh
@@ -0,0 +1,87 @@
+#!/bin/sh
+
+#
+# Copyright (c) 2022 Jason Harmening <jah@FreeBSD.org>
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions
+# are met:
+# 1. Redistributions of source code must retain the above copyright
+#    notice, this list of conditions and the following disclaimer.
+# 2. Redistributions in binary form must reproduce the above copyright
+#    notice, this list of conditions and the following disclaimer in the
+#    documentation and/or other materials provided with the distribution.
+#
+# THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+# ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+# ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+# FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+# DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+# OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+# HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+# OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+# SUCH DAMAGE.
+#
+
+[ `id -u ` -ne 0 ] && echo "Must be root!" && exit 1
+
+# Regression test:
+
+# There is an issue, namely, when the lower file is already
+# opened r/w, but its nullfs alias is executed. This situation obviously
+# shall result in ETXTBUSY, but it currently does not.
+
+# Based on nullfs10.sh by pho@, original test scenario by kib@
+
+. ../default.cfg
+
+md1=$mdstart
+md2=$((md1 + 1))
+mp1=/mnt$md1
+mp2=/mnt$md2
+mkdir -p $mp1 $mp2
+set -e
+for i in $mp1 $mp2; do
+	mount | grep -q "on $i " && umount -f $i
+done
+for i in $md1 $md2; do
+	mdconfig -l | grep -q md$i && mdconfig -d -u $i
+done
+
+mdconfig -a -t swap -s 4g -u $md1
+mdconfig -a -t swap -s 4g -u $md2
+newfs $newfs_flags -n md$md1 > /dev/null
+newfs $newfs_flags -n md$md2 > /dev/null
+mount /dev/md$md1 $mp1
+mount /dev/md$md2 $mp2
+
+mount -t unionfs -o noatime $mp1 $mp2
+set +e
+
+mount | grep -E "$mp1|$mp2"
+
+chmod 777 $mp1
+chmod 777 $mp2
+
+cp /bin/ls $mp2
+chmod +w $mp2/ls
+sleep 2 >> $mp2/ls &
+sleep .5
+
+# This line should cause a "$mp1/ls: Text file busy" error
+$mp1/ls -l /bin/ls $mp1 $mp2 && echo FAIL || echo OK
+kill $!
+wait
+
+while mount | grep -q "$mp2 "; do
+	umount $mp2 || sleep 1
+done
+
+while mount | grep -q "$mp1 "; do
+	umount $mp1 || sleep 1
+done
+mdconfig -d -u $md2
+mdconfig -d -u $md1
diff --git a/tools/test/stress2/misc/unionfs12.sh b/tools/test/stress2/misc/unionfs12.sh
new file mode 100755
index 000000000000..62d1b494cda9
--- /dev/null
+++ b/tools/test/stress2/misc/unionfs12.sh
@@ -0,0 +1,88 @@
+#!/bin/sh
+
+#
+# Copyright (c) 2022 Jason Harmening <jah@FreeBSD.org>
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions
+# are met:
+# 1. Redistributions of source code must retain the above copyright
+#    notice, this list of conditions and the following disclaimer.
+# 2. Redistributions in binary form must reproduce the above copyright
+#    notice, this list of conditions and the following disclaimer in the
+#    documentation and/or other materials provided with the distribution.
+#
+# THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+# ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+# ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+# FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+# DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+# OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+# HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+# OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+# SUCH DAMAGE.
+#
+
+[ `id -u ` -ne 0 ] && echo "Must be root!" && exit 1
+
+# Regression test:
+
+# There is an issue, namely, when the lower file is already
+# opened r/w, but its nullfs alias is executed. This situation obviously
+# shall result in ETXTBUSY, but it currently does not.
+
+# Based on nullfs10.sh by pho@, original test scenario by kib@
+
+. ../default.cfg
+
+md1=$mdstart
+md2=$((md1 + 1))
+mp1=/mnt$md1
+mp2=/mnt$md2
+mkdir -p $mp1 $mp2
+set -e
+for i in $mp1 $mp2; do
+	mount | grep -q "on $i " && umount -f $i
+done
+for i in $md1 $md2; do
+	mdconfig -l | grep -q md$i && mdconfig -d -u $i
+done
+
+mdconfig -a -t swap -s 4g -u $md1
+mdconfig -a -t swap -s 4g -u $md2
+newfs $newfs_flags -n md$md1 > /dev/null
+newfs $newfs_flags -n md$md2 > /dev/null
+mount /dev/md$md1 $mp1
+mount /dev/md$md2 $mp2
+
+mkdir $mp2/shadow
+cp /bin/ls $mp2/shadow/
+mount -t unionfs -o noatime $mp1 $mp2
+set +e
+
+mount | grep -E "$mp1|$mp2"
+
+chmod 777 $mp1
+chmod 777 $mp2
+
+chmod +w $mp2/shadow/ls
+sleep 2 >> $mp2/shadow/ls &
+sleep .5
+
+# This line should cause a "$mp1/shadow/ls: Text file busy" error
+$mp1/shadow/ls -l /bin/ls $mp1 $mp2 && echo FAIL || echo OK
+kill $!
+wait
+
+while mount | grep -q "$mp2 "; do
+	umount $mp2 || sleep 1
+done
+
+while mount | grep -q "$mp1 "; do
+	umount $mp1 || sleep 1
+done
+mdconfig -d -u $md2
+mdconfig -d -u $md1