powerpc/numa: Do not update sysfs cpu registration from invalid context

commit dd023217e17e72b46fb4d49c7734c426938c3dba upstream.

The topology update code that updates the cpu node registration in sysfs
should not be called while in stop_machine(). The register/unregister
calls take a lock and may sleep.

This patch moves these calls outside of the call to stop_machine().

Signed-off-by: Nathan Fontenot <nfont@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 3 insertions, 2 deletions

diff --git a/arch/powerpc/mm/numa.c b/arch/powerpc/mm/numa.c
index 88c0425dc0a8..2859a1f52279 100644
--- a/arch/powerpc/mm/numa.c
+++ b/arch/powerpc/mm/numa.c
@@ -1433,11 +1433,9 @@ static int update_cpu_topology(void *data)
                 if (cpu != update->cpu)
                         continue;
 
-                unregister_cpu_under_node(update->cpu, update->old_nid);
                 unmap_cpu_from_node(update->cpu);
                 map_cpu_to_node(update->cpu, update->new_nid);
                 vdso_getcpu_init();
-                register_cpu_under_node(update->cpu, update->new_nid);
         }
 
         return 0;
@@ -1485,6 +1483,9 @@ int arch_update_cpu_topology(void)
         stop_machine(update_cpu_topology, &updates[0], &updated_cpus);
 
         for (ud = &updates[0]; ud; ud = ud->next) {
+                unregister_cpu_under_node(ud->cpu, ud->old_nid);
+                register_cpu_under_node(ud->cpu, ud->new_nid);
+
                 dev = get_cpu_device(ud->cpu);
                 if (dev)
                         kobject_uevent(&dev->kobj, KOBJ_CHANGE);