From 936260e3ad3dde5641e10ed56e982bbe6a24a9ca Mon Sep 17 00:00:00 2001
From: Nathan Fontenot <nfont@linux.vnet.ibm.com>
Date: Fri, 26 Jan 2018 13:41:59 -0600
Subject: [PATCH] powerpc/numa: Invalidate numa_cpu_lookup_table on cpu remove
References: FATE#323746, bsc#1079524
Patch-mainline: queued
Git-repo: https://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux.git
Git-commit: 1d9a090783bef19fe8cdec878620d22f05191316
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.
This bug looks like it was introduced in 2004 in the commit titled
"ppc64: cpu hotplug notifier for numa", which is 6b15e4e87e32 in the
linux-fullhist tree. Hence tag it for all stable releases.
Cc: stable@vger.kernel.org
Signed-off-by: Nathan Fontenot <nfont@linux.vnet.ibm.com>
Reviewed-by: Tyrel Datwyler <tyreld@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Acked-by: Michal Suchanek <msuchanek@suse.de>
---
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 14764844f0f6..24515bd6f5b3 100644
--- a/arch/powerpc/include/asm/topology.h
+++ b/arch/powerpc/include/asm/topology.h
@@ -44,6 +44,11 @@ extern void __init dump_numa_cpu_topology(void);
extern int sysfs_add_device_to_node(struct device *dev, int nid);
extern void sysfs_remove_device_from_node(struct device *dev, int nid);
+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 00c8b78597c5..612c0aa54ac9 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 92b8a4447c94..83a551cfa575 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)
--
2.13.6