From: Anton Blanchard <anton@samba.org>


Anton has been testing odd setups:

/* node 0 - no cpus, no memory */
/* node 1 - 1 cpu, no memory */
/* node 2 - 0 cpus, 1GB memory */
/* node 3 - 3 cpus, 3GB memory */

Two things tripped so far.  Firstly the ppc64 debug check for invalid cpus
in cpu_to_node().  Fix that in kernel/sched.c:node_nr_running_init().

The other problem concerned nodes with memory but no cpus.  kswapd tries to
set_cpus_allowed(0) and bad things happen.  So we only set cpu affinity
for kswapd if there are cpus in the node.