Re: [cobalt-users] unfamiliar error message in /var/log/messages

[jens@xxxxxxxxxxxxxxxxxxxx (Jens Kristian Søgaard)]

Albert Croft <acroft@xxxxxxxxxxxxxxxx> writes:

> I found the following error message on a server I work with today in
> /var/log/messages while trying to determine what caused it to stop
> responding. The machine is running a 2.2.13C kernel, and I am trying to
> determine if the likely cause was a physical memory problem, or simply a
> lack of memory or other software problem. The message, which appeared
> numerous times, was:
> kernel: kmem_alloc: Bad slab magic (corrupt) (name=buffer_head)
> Anyone familiar with it?

It means that the SLAB object cache of the kernel was somehow
corrupted. The SLAB magic is a kind of "watermark" that tracks the end
of the cache -- but somehow this watermark wasn't at it's right place
at all.

It isn't a "lack of memory"-problem, as the kernel would never throw a
slab magic corrupt error, when out of memory (the error comes from the
cache alloc routine, and that is using kernel memory - not user
space).

If this happens for you repeately, I would say it's a physical memory
problem or an overheated CPU.

If it was a one-timer, I would say a weird kernel bug that shows up
once in a lifetime.

-- 
Jens Kristian Søgaard, Mermaid Consulting I/S,
jens@xxxxxxxxxxxxxxxxxxxx,
http://www.mermaidconsulting.com/