[DC LoCo] Kernel Panic!

[Barry Warsaw]

On Feb 01, 2011, at 01:23 PM, Frank J. Gómez wrote:

>I have a server running Ubuntu 10.04 LTS Server Edition.  It worked fine
>until...

I'm running 10.04.1 on both of my primary servers.  Both are running the
2.6.32-28 kernel.

>*Possible culprit #1*
>When I logged in this morning it told me I needed to reboot to complete some
>updates.  I presume this was for the same kernel updates I got recently on
>my laptop.
>
>*Possible culprit #2*
>I unplugged a USB hard drive (mounted either at /mnt or /media/some-folder
>-- I don't remember which) without unmounting it first -- I forgot was
>mounted :-(.
>
>Shortly after PC#2 occurred, the machine became unresponsive via SSH.  I
>hooked up a monitor and keyboard directly and couldn't get anything out of
>it.
>
>On reboot, I'm getting messages about a kernel panic with a call trace
>mentioning no_context, __bad_area_nosemaphore, do_page_fault, and other
>friends.
>
>On rereboot, holding the Shift key does not bring up Grub2 to let me try
>booting off the previous kernel.
>
>I'm not sure where to begin restoring sanity to the world.  Can anyone point
>me in the right direction?

I suppose it could be about anything, but my guess is that the reboot to get
the new kernel is the culprit.  I'd kind of be surprised that the USB unmount
would affect the machine after multiple reboots.  Have you done any memory or
other hardware diagnostics on it?

There are several things you can try to fix the problem, of course depending
on what is actually broken.  It might be as easy as re-installing grub into
the MBR:

https://help.ubuntu.com/community/RecoveringUbuntuAfterInstallingWindows

Good luck!
-Barry
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