Comment 7 for bug 29187

Maybe we could use the same fix that debian did?

My /mnt/sid/etc/init.d/umountroot has these lines:

do_stop () {
 [ "$VERBOSE" = no ] || log_action_begin_msg "Mounting root filesystem read-only"
 MOUNT_FORCE_OPT=
 [ "$(uname -s)" = "GNU/kFreeBSD" ] && MOUNT_FORCE_OPT=-f
 # This:
 # mount -n -o remount,ro /
 # will act on a bind mount of / if there is one.
 # See #339023 and the comment in checkroot.sh
 mount $MOUNT_FORCE_OPT -n -o remount,ro -t dummytype dummydev / 2>/dev/null \
 || mount $MOUNT_FORCE_OPT -n -o remount,ro dummydev / 2>/dev/null \
 || mount $MOUNT_FORCE_OPT -n -o remount,ro /
 ES=$?
 [ "$VERBOSE" = no ] || log_action_end_msg $ES
}

Specifying a device, even if it's "dummydev" seems to do the trick.