Panic on -CURRENT after LDT changes

Joe Marcus Clarke marcus at marcuscom.com
Fri May 25 18:22:23 UTC 2007


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Attilio Rao wrote:
> 2007/5/25, Joe Marcus Clarke <marcus at marcuscom.com>:
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>> Attilio Rao wrote:
>> > 2007/5/24, Joe Marcus Clarke <marcus at marcuscom.com>:
>> >> On Thu, 2007-05-24 at 20:13 +0200, Attilio Rao wrote:
>> >> > Jeff Roberson wrote:
>> >> > > Thanks,  Attilio and I will look at this right away.
>> >> > >
>> >> > > Jeff
>> >> > >
>> >> > > On Wed, 23 May 2007, Joe Marcus Clarke wrote:
>> >> > >
>> >> > >> On a -CURRENT build today with Jeff's LDT locking changes, I
>> get an
>> >> > >> instant, reproducible panic by doing:
>> >> > >>
>> >> > >> # cd /usr/src
>> >> > >> # make -DNO_CLEAN buildworld
>> >> > >>
>> >> > >> Backing out the LDT changes to /sys/i386/i386/*machdep*
>> corrects the
>> >> > >> problem.  Here is a dmesg and backtrace.  In frame 6, it appears
>> >> mdp is
>> >> > >> NULL (i.e. td->td_proc->p_md = 0x0).
>> >> >
>> >> > Did you enable WITNESS/INVARIANTS/INVARIANT_SUPPORT?
>> >>
>> >> No, this kernel does not have WITNESS or INVARIANTS.  I can enable
>> those
>> >> tomorrow if that would give you more useful information.
>> >
>> > It would be very appreciated, since I've been unable to reproduce your
>> > panic on a centrino dual core.
>>
>> I'm stopped in the debugger now with WITNESS and friends enabled.  Same
>> backtrace as before.  I did a "show locks" and I see:
>>
>> exclusive spin mutex descriptor tables r = 0 (0xc08369f8) locked @
>> /usr/src/sys/i386/i386/sys_machdep.c:629
>>
>> Please let me know what else you'd like to see while I'm at the
>> debugger.  FYI: this is a Pentium 4 with "options SMP" disabled.
> 
> This is a multicore? do you have PREEMPTION/FULL_PREEMPTION installed?

No, single core with PREEMPTION enabled only.

Joe

> 
> Attilio
> 
> 


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