spin lock sched lock held by 0xffffff007b712250 for > 5 seconds

[Robert Watson]

On Fri, 16 Jul 2004, Willem Jan Withagen wrote:

> After todays kernelbuild the system seem to be a lot better...
> It can take quite some buildworld abuse, but still:
> 
> spin lock sched lock held by 0xffffff007b712250 for > 5 seconds
> panic: spin lock held too long
> cpuid = 1;
> KDB: enter: panic
> 
> But I'm not shure what I could/should do now, since the KDB
> introduction.  Normally I'd expect to see:  db>

We have trouble entering the debugger when in a critical section/and or
have sched_lock held -- I think this is because we try to halt the other
CPUs and that gets nastily stuck in some form.  We need to fix this.

This could well be a symptom of some of the other hangs we've been seeing,
and I've seen similar things on my test box with preemption enabled.

Robert N M Watson             FreeBSD Core Team, TrustedBSD Projects
robert at fledge.watson.org      Principal Research Scientist, McAfee Research