When DLPAR removing a CPU, the unmapping of the cpu from a node in
unmap_cpu_from_node() should also invalidate the CPUs entry in the
numa_cpu_lookup_table. There is not a guarantee that on a subsequent
DLPAR add of the CPU the associativity will be the same and thus
could be in a different node. Invalidating the entry in the
numa_cpu_lookup_table causes the associativity to be read from the
device tree at the time of the add.
The current behavior of not invalidating the CPUs entry in the
numa_cpu_lookup_table can result in scenarios where the the topology
layout of CPUs in the partition does not match the device tree
or the topology reported by the HMC.
Signed-off-by: Nathan Fontenot <nf...@linux.vnet.ibm.com>
---
Originally sent Dec. 5 2017, no reply, resending.
Updates for V2: Move the invalidation from unmap_cpu_from_node to
pseries_remove_processor, the former routine is also called during cpu
offline and we do not want to invalidate during cpu offline.
arch/powerpc/include/asm/topology.h | 5 +++++
arch/powerpc/mm/numa.c | 5 -----
arch/powerpc/platforms/pseries/hotplug-cpu.c | 2 ++
3 files changed, 7 insertions(+), 5 deletions(-)
diff --git a/arch/powerpc/include/asm/topology.h
b/arch/powerpc/include/asm/topology.h
index 88187c285c70..1c02e6900f78 100644
--- a/arch/powerpc/include/asm/topology.h
+++ b/arch/powerpc/include/asm/topology.h
@@ -44,6 +44,11 @@ extern int sysfs_add_device_to_node(struct device *dev, int
nid);
extern void sysfs_remove_device_from_node(struct device *dev, int nid);
extern int numa_update_cpu_topology(bool cpus_locked);
+static inline void update_numa_cpu_lookup_table(unsigned int cpu, int node)
+{
+ numa_cpu_lookup_table[cpu] = node;
+}
+
static inline int early_cpu_to_node(int cpu)
{
int nid;
diff --git a/arch/powerpc/mm/numa.c b/arch/powerpc/mm/numa.c
index 268c7a2d9a5b..7ec3a0d787d3 100644
--- a/arch/powerpc/mm/numa.c
+++ b/arch/powerpc/mm/numa.c
@@ -143,11 +143,6 @@ static void reset_numa_cpu_lookup_table(void)
numa_cpu_lookup_table[cpu] = -1;
}
-static void update_numa_cpu_lookup_table(unsigned int cpu, int node)
-{
- numa_cpu_lookup_table[cpu] = node;
-}
-
static void map_cpu_to_node(int cpu, int node)
{
update_numa_cpu_lookup_table(cpu, node);
diff --git a/arch/powerpc/platforms/pseries/hotplug-cpu.c
b/arch/powerpc/platforms/pseries/hotplug-cpu.c
index a7d14aa7bb7c..09083ad82f7a 100644
--- a/arch/powerpc/platforms/pseries/hotplug-cpu.c
+++ b/arch/powerpc/platforms/pseries/hotplug-cpu.c
@@ -36,6 +36,7 @@
#include <asm/xics.h>
#include <asm/xive.h>
#include <asm/plpar_wrappers.h>
+#include <asm/topology.h>
#include "pseries.h"
#include "offline_states.h"
@@ -331,6 +332,7 @@ static void pseries_remove_processor(struct device_node *np)
BUG_ON(cpu_online(cpu));
set_cpu_present(cpu, false);
set_hard_smp_processor_id(cpu, -1);
+ update_numa_cpu_lookup_table(cpu, -1);
break;
}
if (cpu >= nr_cpu_ids)
