Matthias Drochner <M.Drochner@fz-juelich.de> writes:

> The reason is obvious: sys_ptrace() calls proc_unstop() and passes
> the result to setrunnable(). And with the process waiting in
> sigsuspend() (ie wchan != 0) a NULL gets passed.
> The obvious fix, checking proc_unstop()'s result, avoids the panic,
> but is not really satisfying because the signal doesn't get
> delivered either.
> The semantics behind proc_unstop() is not easy to understand...

I think I've fixed this with rev 1.133 of kern_sig.c and 1.80 of
sys_process.c, and hyopefully made proc_unstop() a little more sane
along the way.

        - Nathan