The ctl module cannot be unloaded if ctld has ever started. A simple "kldload ctl; kldunload ctl" works, but after starting ctld with "service ctld onestart", then the module cannot be unloaded. somers@fbsd-head /u/h/somers> sudo kldunload ctl kldunload: can't unload file: Device busy somers@fbsd-head /u/h/somers [1]> dmesg | tail -n1 kldunload: attempt to unload file that was loaded by the kernel This problem means that there's no way for ctl to handle SIGKILL except a reboot. If you ever send SIGKILL to that process, it will stay in the process's pending list forever.