Subject: [PATCH v2] Do not update sysfs cpu registration from invalid context

From: Nathan Fontenot <[email-masked]>
Date: Mon, 24 Jun 2013 22:08:05 -0500

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 <[email-masked]>
---
 arch/powerpc/mm/numa.c |    5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

Index: powerpc/arch/powerpc/mm/numa.c
===================================================================
--- powerpc.orig/arch/powerpc/mm/numa.c	2013-06-24 06:53:31.000000000 -0500
+++ powerpc/arch/powerpc/mm/numa.c	2013-06-24 14:28:14.000000000 -0500
@@ -1433,11 +1433,9 @@
 		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 @@
 	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);