Re: [PATCH] Fix early panic issue on machines with memless node

From: David Rientjes
Date: Tue May 05 2009 - 16:41:38 EST


On Tue, 5 May 2009, Jack Steiner wrote:

> I suspect I mislead you when I mentioned "configurations". I did not mean
> the .config file. I use a more-or-less standard .config file.
>

Your .config would still let me build a kernel with debugging symbols so
that your offsets actually made sense to my gdb.

> I do much of my testing on a system simulator. Using a simulator config file,
> I specify the system configuration such as number of nodes, sockets per node,
> cpus per socket, memory per socket, address map, boot options, etc. This
> makes it easy to quickly test a lot of strange (but real) configurations.
>
> The configuration above that is failing is a 2-socket Nehelem blade that has no
> memory on socket 0. All memory is located on socket 1. The panic is caused by a
> null dereference of NODE_DATA(0).
>

A NULL dereference of NODE_DATA(0) should never happen even with
!CONFIG_NEED_MULTIPLE_NODES. So when you say the panic is caused by that
(and I'm speculating since all I've seen is a call trace and not the
entire panic), I'm assuming it's because NODE_DATA(0)->node_zones + offset
is NULL because node 0 has no memory?
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