Worth persuing a KDB: stack backtrace: ?

Tuc ml at t-b-o-h.net
Sat Oct 11 17:42:59 UTC 2008


> 
> On Sat, Oct 11, 2008 at 11:22:21AM -0400, Tuc wrote:
> > 	I have a 5.5-STABLE laptop thats been having issues lately, mostly
> > related to memory. I bought new chips, and I think I narrowed it down to one
> > of the Dimm slots being bad. I did a memtest for 25 hours and it seemed stable.
> 
> memtest86+ would definitely detect a DIMM slot being bad, so running it
> for 25 hours successfully means the DIMM and the DIMM slot is likely fine.
>
	Sorry, 2 corrections. :)  

	1) I ran memtest86+ 3.4
	2) If I tried to run the memory test on the slot I thought was bad, 
it looked like whatever is underneath the memtest86+ (Linux?) would crap out
within 6 seconds of startup. I've only tested the "B" slot after running into
so many issues with the "A" slot (And I checked, you can run one slot only
on this laptop... Dell Inspiron 8200)
> 
> > I started up and started downloading a backup of over 5K emails. (All have
> > to go through mimedefang, procmail and sendmail... So the system was a bit
> > sluggish. I started to get things like :
> > 
> > Oct 10 22:06:29 himinbjorg kernel: KDB: stack backtrace:
> > Oct 10 22:06:29 himinbjorg kernel: kdb_backtrace(c3053200,1,dbb54c04,dbb54bf0,c0
> > 73ba78) at kdb_backtrace+0x29
> > Oct 10 22:06:29 himinbjorg kernel: getdirtybuf(dbb54be0,0,1,cc1c81e8,1) at getdi
> > rtybuf+0x27
> > Oct 10 22:06:29 himinbjorg kernel: flush_deplist(c305354c,1,dbb54c04) at flush_d
> > eplist+0x34
> > Oct 10 22:06:29 himinbjorg kernel: flush_inodedep_deps(c216d000,715e,c089bcf8,c0
> > 808b16,ef) at flush_inodedep_deps+0x7d
> > Oct 10 22:06:29 himinbjorg kernel: softdep_sync_metadata(dbb54ca0) at softdep_sy
> > nc_metadata+0x8c
> > Oct 10 22:06:29 himinbjorg kernel: ffs_fsync(dbb54ca0) at ffs_fsync+0x33e
> > Oct 10 22:06:29 himinbjorg kernel: fsync(c3549600,dbb54d04,1,1,286) at fsync+0x1
> > 03
> > Oct 10 22:06:29 himinbjorg kernel: syscall(2f,2f,bfbf002f,80fef20,0) at syscall+
> > 0x227
> > Oct 10 22:06:29 himinbjorg kernel: Xint0x80_syscall() at Xint0x80_syscall+0x1f
> > Oct 10 22:06:29 himinbjorg kernel: --- syscall (95, FreeBSD ELF32, fsync), eip =
> >  0x28181ca7, esp = 0xbfbf6d1c, ebp = 0xbfbf86e8 ---
> 
> This looks more like a filesystem problem, not a memory problem.  All
> of the functions listed in the backtrace show UFS/FFS problems and
> filesystem metadata issues of some kind.
>
	Yup, sorry. I should have said that I realized it was a disk issue, but
that I was thinking that maybe it wasn't really the OS's fault that there are
"deeper" problems with the laptop that could be manifesting themselves here.
When I sent all sorts of copious debug to Dell they just told me to replace
the motherboard completely. I didn't want to spend the $$. At first all the
problems manifested as memory, memtest86+ would lock up, "crash", etc with the
memory I had. I bought new memory ($50 for a gig) BEFORE Dell just told me to
replace the whole motherboard. With the new memory in, only using the "B" slot,
it appeared more stable. I found these issues only accidentally. I tend to
type "dmesg" when my fingers are idle and my brain is spinning thinking of
something and thats when I saw this cruft.
>
> Booting the machine in single-user mode and run "fsck -y".  I'm betting
> you'll find errors.  If not, then it's probably a kernel bug -- see
> below, however.
>
	Probably could use it, yea. It had locked up a few times so I'm
sure the filesystems weren't in great shape. I thought I had offline 
fsck'd them, but now not so sure.
> 
> I doubt you're going to get much support on this, since you're running
> FreeBSD 5.5, which is no longer supported.  Believe me: you will get
> continual push-back from the rest of the FreeBSD developers asking for
> support on 5.5.  The RELENG_6 series is on its way out as well, so
> you should consider installing RELENG_7 (specifically 7.1-BETA at
> this point).
> 
	Well, that was 1/2 of the reason why I asked if it was even
worth it to trace it out. 1/2 was the fact its 5.5, the other 1/2 was
that I've already been told to replace the motherboard. :)

	I tried going to 6.X on this machine for a few weeks once before, 
constantly locked up in the booting of the kernel. I haven't had a spare 
second otherwise to consider going to 7. I didn't think anyone would
really want to help on 5.5, but figured I'd toss it out there and see if
anyone thought it worth while.

	Thanks Jeremy.

			Tuc


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