When converting to the new cpumask code I screwed up:
-       if (cpu_isset(cpu, numa_cpumask_lookup_table[node])) {
-               cpu_clear(cpu, numa_cpumask_lookup_table[node]);
+       if (cpumask_test_cpu(cpu, node_to_cpumask_map[node])) {
+               cpumask_set_cpu(cpu, node_to_cpumask_map[node]);
This was introduced in commit 
25863de07af9 (powerpc/cpumask: Convert NUMA code
to new cpumask API)
Fix it.
Signed-off-by: Anton Blanchard <anton@samba.org>
Cc: <stable@kernel.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
        dbg("removing cpu %lu from node %d\n", cpu, node);
 
        if (cpumask_test_cpu(cpu, node_to_cpumask_map[node])) {
-               cpumask_set_cpu(cpu, node_to_cpumask_map[node]);
+               cpumask_clear_cpu(cpu, node_to_cpumask_map[node]);
        } else {
                printk(KERN_ERR "WARNING: cpu %lu not found in node %d\n",
                       cpu, node);