From: Anton Blanchard <anton@samba.org>

We were hitting problems on machines with cpu_possible != cpu_online when
NUMA was enabled.  The debug checks would trip during scheduler init
because we iterate through all possible cpus whereas we only set up NUMA
information for online cpus.

Longer term we should have a cpu_up hook which sets up its NUMA information
but for now we initalise all possible cpus and memory to node 0.