Double fault during reboot/shutdown

[Matthew Dillon <dillon@xxxxxxxxxxxxxxxxxxxx>]

    A recent commit at some point in the last few weeks is causing
    real-kernel reboots and shutdowns to ocassionally double-fault.
    vkernels also occassionally seg-fault on shutdown.

    I'm going to attempt to track this down.  I'm fairly sure that it is
    not related to any of my work, however.

						-Matt