kernel panic mounting /tmp - 6.2-PRERELEASE

[Brooks Davis]

On Wed, Oct 18, 2006 at 12:25:58AM +1000, Norberto Meijome wrote:
> Hi everyone,
> 
> tonight when I started my laptop, i was welcomed with a very nice panic, which
> was happening JUST when mounting the filesystems. 
> 
> Some info:
> Fault code : supervisor read, page not present.
> current process : 112 (mount)
> trap 12
> panic :page fault
> 
> with nm -m I saw that the following procs where candidates ...
> 
> ufsdirhash_build
> ufsdirhas_free
> ufsdirhash_lookup
> 
> Booting with 6.1 Release CD and mounting showed no obvious problems at all, but
> the panic could be reproduced every time with this particular kernel (6 days
> old). Commenting out /tmp in fstab worked around the problem.
> 
> recreating the filesystem in /dev/ad0s1e (my /tmp) solved the problem and now
> everything is back to normal. The computer works great as usual.
> 
> $ uname -a
> FreeBSD ayiin.xxx 6.2-PRERELEASE FreeBSD 6.2-PRERELEASE #14:
> Wed Oct 11 14:13:49 EST 2006
> root at ayiin.xxx:/usr/obj/usr/src/sys/AYIIN  i386
> 
> I have a good kernel dump , a copy of /boot/kernel that was being used, and a
> dump (dump -0 -a -f usr/ad0s1e.dump /dev/ad0s1e ) of the /tmp partition at the
> time (before the newfs, of course). Available for anyone interested.
> 
> Is there a bigger issue here? anything I can do to help diagnose / debug this?

Possibly and no.  By recreating the file system you've destroyed
the information needed to isolate the cause.  It's known that an
appropriately corrupt file system can do this, but the causes (there are
probably several) are not yet known.  There is some speculation that the
only solution is to add checksums to all key data sections.

-- Brooks
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