Re: kern/68442: panic - acquiring duplicate lock of same type: "sleepq chain"

On Tue, Jun 29, 2004 at 08:35:57PM +0200, Daniel Lang wrote:
> Hi Brian,
> 
> Brian Fundakowski Feldman wrote on Tue, Jun 29, 2004 at 01:00:14PM -0400:
> [..]
> > You can find it out without using gdb, too.  This will work for
> > only main kernel symbols, but you can do something similar for
> > KLDs.  Say I want to find a symbol that's in the main kernel object:
> > 
> > $ objdump -t /boot/kernel/kernel | ruby -ne 'fields = $_.split; if fields[3] == ".text" and fields[2] == "F" and 0xc048a800.between?(fields[0].hex, fields[0].hex + fields[4].hex) then puts $_ end'
> > c048a7ac l     F .text  0000006b cbb_removal
> [..]
> 
> Thanks for that hint, but Colin suggested to use "addr2line", which
> produced some result. Maybe addr2line does a similar thing
> as your objdump/ruby script:

Yeah, as long as it's in the main kernel object and you have debug
symbols.

> So I have a line of code for the failing address:
> 
> # addr2line -e kernel.debug 0xc053932b
> /usr/src/sys/kern/subr_witness.c:898
> 
> which is (in my kernel):
> 
> [..]
>         lock1 = &(*lock_list)->ll_children[(*lock_list)->ll_count - 1];
> [..]
> 
> Well, I'm not sure if this is a big help. I doubt there is a bug
> in witness code.

Looks like a lock was cleared out/freed/whatever but not actually
deinitialized first?

> I'll cross-check with gdb to see if there is the same
> result. Too bad I couldn't get a crashdump. 
> 
> (What hurts most, is, that in one occasion I had a ddb prompt
> and could call doadump() successfully. But after reboot, damn 
> /var was full, so savecore could not write it to disk, argl!).

You can make /var/crash a symlink to a directory with more space.

-- 
Brian Fundakowski Feldman                           \'[ FreeBSD ]''''''''''\
  <> green_at_FreeBSD.org                               \  The Power to Serve! \
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