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Commit 81b61324 authored by Nathan Fontenot's avatar Nathan Fontenot Committed by Michael Ellerman
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powerpc/pseries: Perform full re-add of CPU for topology update post-migration 



On pseries systems, performing a partition migration can result in
altering the nodes a CPU is assigned to on the destination system. For
exampl, pre-migration on the source system CPUs are in node 1 and 3,
post-migration on the destination system CPUs are in nodes 2 and 3.

Handling the node change for a CPU can cause corruption in the slab
cache if we hit a timing where a CPUs node is changed while cache_reap()
is invoked. The corruption occurs because the slab cache code appears
to rely on the CPU and slab cache pages being on the same node.

The current dynamic updating of a CPUs node done in arch/powerpc/mm/numa.c
does not prevent us from hitting this scenario.

Changing the device tree property update notification handler that
recognizes an affinity change for a CPU to do a full DLPAR remove and
add of the CPU instead of dynamically changing its node resolves this
issue.

Signed-off-by: default avatarNathan Fontenot <nfont@linux.vnet.ibm.com>
Signed-off-by: default avatarMichael W. Bringmann <mwb@linux.vnet.ibm.com>
Tested-by: default avatarMichael W. Bringmann <mwb@linux.vnet.ibm.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
parent 63da6cae

arch/powerpc/include/asm/topology.h

+2 −0
Original line number Original line Diff line number Diff line
@@ -132,6 +132,8 @@ static inline void shared_proc_topology_init(void) {} 
#define topology_sibling_cpumask(cpu)	(per_cpu(cpu_sibling_map, cpu))

#define topology_sibling_cpumask(cpu)	(per_cpu(cpu_sibling_map, cpu))

#define topology_core_cpumask(cpu)	(per_cpu(cpu_core_map, cpu))

#define topology_core_cpumask(cpu)	(per_cpu(cpu_core_map, cpu))

#define topology_core_id(cpu)		(cpu_to_core_id(cpu))

#define topology_core_id(cpu)		(cpu_to_core_id(cpu))



int dlpar_cpu_readd(int cpu);

#endif

#endif

#endif

#endif

arch/powerpc/mm/numa.c

+1 −8
Original line number Original line Diff line number Diff line
@@ -1460,13 +1460,6 @@ static void reset_topology_timer(void) 




#ifdef CONFIG_SMP

#ifdef CONFIG_SMP





static void stage_topology_update(int core_id)

{

	cpumask_or(&cpu_associativity_changes_mask,

		&cpu_associativity_changes_mask, cpu_sibling_mask(core_id));

	reset_topology_timer();

}



static int dt_update_callback(struct notifier_block *nb,

static int dt_update_callback(struct notifier_block *nb,

				unsigned long action, void *data)

				unsigned long action, void *data)

{

{
@@ -1479,7 +1472,7 @@ static int dt_update_callback(struct notifier_block *nb, 
		    !of_prop_cmp(update->prop->name, "ibm,associativity")) {

		    !of_prop_cmp(update->prop->name, "ibm,associativity")) {

			u32 core_id;

			u32 core_id;

			of_property_read_u32(update->dn, "reg", &core_id);

			of_property_read_u32(update->dn, "reg", &core_id);

			stage_topology_update(core_id);

			rc = dlpar_cpu_readd(core_id);

			rc = NOTIFY_OK;

			rc = NOTIFY_OK;

		}

		}

		break;

		break;

arch/powerpc/platforms/pseries/hotplug-cpu.c

+19 −0
Original line number Original line Diff line number Diff line
@@ -802,6 +802,25 @@ static int dlpar_cpu_add_by_count(u32 cpus_to_add) 
	return rc;

	return rc;

}

}





int dlpar_cpu_readd(int cpu)

{

	struct device_node *dn;

	struct device *dev;

	u32 drc_index;

	int rc;



	dev = get_cpu_device(cpu);

	dn = dev->of_node;



	rc = of_property_read_u32(dn, "ibm,my-drc-index", &drc_index);



	rc = dlpar_cpu_remove_by_index(drc_index);

	if (!rc)

		rc = dlpar_cpu_add(drc_index);



	return rc;

}



int dlpar_cpu(struct pseries_hp_errorlog *hp_elog)

int dlpar_cpu(struct pseries_hp_errorlog *hp_elog)

{

{

	u32 count, drc_index;

	u32 count, drc_index;