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Date: Fri, 16 Jul 2004 12:21:09 -0400 (EDT)
From: Robert Watson <rwatson@freebsd.org>
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To: Willem Jan Withagen <wjw@withagen.nl>
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cc: freebsd-current@freebsd.org
Subject: Re: spin lock sched lock held by 0xffffff007b712250 for > 5 seconds
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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@fledge.watson.org      Principal Research Scientist, McAfee Research