Re: sysctl -a causes kernel trap 12

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On 01/18/13 12:50, Brandon Gooch wrote:
> On Thu, Jan 10, 2013 at 4:25 PM, Xin Li <delphij_at_delphij.net 
> <mailto:delphij_at_delphij.net>> wrote:
> 
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> 
> To all: this became more and more hard to replicate lately.  I've 
> tried these options and the most important progress is that it's 
> possible to get a crashdump when debug.debugger_on_panic=0 and I 
> managed to get a backtrace which indicates the panic occur when
> trying to do mtx_lock(&Giant) -> __mtx_lock_sleep -> turnstile_wait
> -> propagate_priority, but after I've added some instruments to
> the surrounding code and enabled INVARIANT and/or WITNESS, it
> mysteriously went away.
> 
> Reverting my instruments code and update to latest svn makes the
> issue disappear for one day.  I've hit it again today but
> unfortunately didn't get a successful dump and after reboot I can't
> reproduce it again :(
> 
> Still trying...
> 
> 
> Any updates Xin?

No, it mysteriously disappeared for now.  According to my
understanding to recent svn commits, I didn't see anybody committing
something that fixes it but I can no longer panic my system, with or
without debugging code :(

> I was actually hitting what I believe to be exactly the same issue
> as you on one of my systems, and, as you've seen, adding any extra 
> debugging or diagnostics seemed to eliminate the issue.
> 
> I was able to generate quite a few vmcores and still have these
> sitting around in my filesystem (along with the kernels that helped
> produce them).
> 
> I can recreate this crash on my system by compiling the NVIDIA
> driver with clang at -01 and above. Although it's been noted that
> this issue has been seen in scenarios without an NIVIDIA driver in
> the mix, whatever is happening in the kernel to cause the panic is
> somehow triggered by this, at least on my system.

I'm not sure if this is the same problem.  Could you please try using
gcc to compile the nVIdia driver and see if that "fixes" the problem?

Cheers,
- -- 
Xin LI <delphij_at_delphij.net>    https://www.delphij.net/
FreeBSD - The Power to Serve!           Live free or die
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