systemd/test/test-execute/exec-protectkernelmodules-yes-mount-propagation.service

[Unit]
Description=Test to make sure that passing ProtectKernelModules=yes disconnect mount propagation

[Service]
ProtectKernelModules=yes
ExecStart=/bin/sh -x -c 'd=$$(mktemp -d -p /tmp); trap "umount \'$$d\' && rmdir \'$$d\'" EXIT; mount -t tmpfs tmpfs "$$d"; grep "$$d" /proc/self/mountinfo && ! grep "$$d" /proc/$${PPID}/mountinfo && ! grep "$$d" /proc/1/mountinfo'
Type=oneshot