powerpc/numa: ensure per-cpu NUMA mappings are correct on topology update

We received a report of warning in kernel/sched/core.c where the sched
group was NULL on an LPAR after a topology update. This seems to occur
because after the topology update has moved the CPUs, cpu_to_node is
returning the old value still, which ends up breaking the consistency of
the NUMA topology in the per-cpu maps. Ensure that we update the per-cpu
fields when we re-map CPUs.

Signed-off-by: Nishanth Aravamudan <[email protected]>
Signed-off-by: Michael Ellerman <[email protected]>

Author: Nishanth Aravamudan

arch/powerpc/mm/numa.c

@@ -1509,11 +1509,14 @@ static int update_cpu_topology(void *data)
 	cpu = smp_processor_id();
 
 	for (update = data; update; update = update->next) {
+		int new_nid = update->new_nid;
 		if (cpu != update->cpu)
 			continue;
 
 		unmap_cpu_from_node(cpu);
-		map_cpu_to_node(cpu, update->new_nid);
+		map_cpu_to_node(cpu, new_nid);
+		set_cpu_numa_node(cpu, new_nid);
+		set_cpu_numa_mem(cpu, local_memory_node(new_nid));
 		vdso_getcpu_init();
 	}