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Re: Mount is halfway broken

on Thu, May 10, 2001 at 10:54:18PM -0500, Astrogeek (dude@failsure.net) wrote:
> On my unstable box, "mount -a" segfaults.  It gives the following error (lots
> of stuff snipped):

An interesting mystery.

> <1>Unable to handle kernel NULL pointer dereference at virtual address[...]
> [...]
> pmd entry cbb49000: 0000000000000000
> ... pmd not present!
> [...]
> I woke up this morning and everything was unmounted.  I actually found
> that kind of odd :-)  Windows instincts somehow kicked in and I
> rebooted.  And mount segfaulted giving me only the NFS mounts, /,
> /proc and /dev.  I have to manually mount several partitions.  dmesg
> also segfaults, and I can't see if anything else is going wrong as
> (since /var is on a separate partition) I have no kernel log!  I've
> been messing with it for a couple hours now, I have:
> 1) Installed mount/util-linux from testing and stable and compiled
>    from source
> 2) Downgraded libc6 to testing and back again, no change
> 3) Removed and tested each stick of RAM in the machine, and some
>    add-on cards 
> 4) Memtest came up with no errors on five runs
> 5) Tried different kernel versions (all 2.4.x, running 2.4.4-ac6)
> 6) strace mount -a doesn't show anything obvious (to me) except at the end
> +++ killed by SIGSEGV +++

You usually need to trace back through the command list a bit -- usually
less than a screenful, occasionally more.  If you can't work it out
yourself, post, say, the last 100 lines of strace output to list.

> Mounting each partition individually, as stated above, works for some
> reason.

How about commenting out all but one partition in /etc/fstab, then
adding them back in one at a time, and trying "mount -a" until the
problem appears.  It's odd though that individual mounts work where a
mount -a doesn't.

It might also be helpful for you to post your /etc/fstab as this might
hold some clues.  Partition type / filesystem among them. 

Have you checked the filesystem(s) for errors?

> Before I reinstall, as this is really difficult for me to
> troubleshoot, anybody more experienced have any suggestions?  Nothing
> except mount and dmesg appear to be having trouble.
> The machines running stable are all yawning ;-)  I hope it's not bad
> hardware.  I be broke.

I'm leaning toward HW myself, as it seems like you've been through most
of the SW systems involved.

Karsten M. Self <kmself@ix.netcom.com>    http://kmself.home.netcom.com/
 What part of "Gestalt" don't you understand?       There is no K5 cabal
  http://gestalt-system.sourceforge.net/         http://www.kuro5hin.org

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