vkernel livelocked and core dumped when killed on -HEAD

[Matthew Dillon]

:Tried to cvs checkout the pkgsrc tree and managed to get "intr 1 at 40001/40000
:hz, livelocked limit engaged!". After kill-ing it, it core dumped. The
:backtrace repeats itself over and over, I uploaded kernel and kernel.core to
:leaf:~rumko/crash/vkernel/30.04.2008/

    Did the vkernel actually lock-up or was it still responding?  e.g. did 
    you try ^Z'ing or ^C'ing the checkout?  It is quite possible that
    the IO co-thread actually managed to exceed the livelock limit without
    it being a bug.

    The crash was due to the IO co-thread crashing.  The IO co-thread took
    the shutdown signal from the vkernel when you killed it, but since it
    doesn't have a globaldata context that blew it up.

    I will mask the shutdown signal on the co-thread to fix the core
    dumping issue but we still need to investigate the livelock.  Have
    you been able to reproduce it?

						-Matt