Re: need some debugging help

From: Kenneth D. Merry <ken_at_kdm.org>
Date: Sun, 31 Aug 2003 01:08:54 -0600
On Sat, Aug 30, 2003 at 09:22:10 +0200, Poul-Henning Kamp wrote:
> In message <20030830040357.GA42770_at_panzer.kdm.org>, "Kenneth D. Merry" writes:
> 
> >I think I have everything setup correctly, but I keep getting panics inside
> >the GEOM code with these patches.  (Memory modified after free.)  I don't
> >know whether I've just exposed some race condition, or whether I've done
> >something wrong.
> 
> Do you have any idea what goes on at/right before the panic ?
> 
> Ie: has drives been created [disk_create()] or removed [disk_destroy()]
> right before ?

Well, the panic happens right after the probes complete for the various CAM
devices in the system.

I've got 4 SCSI disks in the system, so disk_create() has just been called
4 times.

That's also the point where I fire off the task queue to create the sysctl
variables for each device, though.  (Right after the probe message is
printed.)

> My best shot, would be that disk_destroy() was called and something
> somehow fiddled the related structures subsequently.
> 
> You may want to set kern.geom.debugflags=N and see if that offers
> any clues.
> 
> 	N |= 1  topology events
> 	N |= 2  bio processing (ie: many lines for each I/O)
> 	N |= 4  access processing (open/close)

I wouldn't expect that disk_destroy() is getting called, although I suppose
that's possible.

I had to make kern.geom.debugflags a tunable in order to get the debugging
output.  (The system panics before root gets mounted, so there's no way to
set a sysctl variable.)

Anyway, I got some debugging output, and I've attached dmesg output.  Let
me know whether anything in there looks suspicious or points to a possible
problem.

Thanks,

Ken
-- 
Kenneth Merry
ken_at_kdm.org

Received on Sat Aug 30 2003 - 22:08:57 UTC

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