[PATCH] powerpc/pseries: Perform full re-add of CPU for topology update post-migration
From: Nathan Fontenot <hidden>
Date: 2018-10-29 19:08:11
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: Nathan Fontenot <redacted> --- arch/powerpc/include/asm/topology.h | 2 ++ arch/powerpc/mm/numa.c | 9 +-------- arch/powerpc/platforms/pseries/hotplug-cpu.c | 19 +++++++++++++++++++ 3 files changed, 22 insertions(+), 8 deletions(-)
diff --git a/arch/powerpc/include/asm/topology.h b/arch/powerpc/include/asm/topology.h
index a4a718dbfec6..f85e2b01c3df 100644
--- a/arch/powerpc/include/asm/topology.h
+++ b/arch/powerpc/include/asm/topology.h@@ -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_core_cpumask(cpu) (per_cpu(cpu_core_map, cpu)) #define topology_core_id(cpu) (cpu_to_core_id(cpu)) + +int dlpar_cpu_readd(int cpu); #endif #endif
diff --git a/arch/powerpc/mm/numa.c b/arch/powerpc/mm/numa.c
index 693ae1c1acba..bb6a7b56bef7 100644
--- a/arch/powerpc/mm/numa.c
+++ b/arch/powerpc/mm/numa.c@@ -1461,13 +1461,6 @@ static void reset_topology_timer(void) #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, unsigned long action, void *data) {
@@ -1480,7 +1473,7 @@ static int dt_update_callback(struct notifier_block *nb, !of_prop_cmp(update->prop->name, "ibm,associativity")) { u32 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; } break;
diff --git a/arch/powerpc/platforms/pseries/hotplug-cpu.c b/arch/powerpc/platforms/pseries/hotplug-cpu.c
index 2f8e62163602..97feb6e79f1a 100644
--- a/arch/powerpc/platforms/pseries/hotplug-cpu.c
+++ b/arch/powerpc/platforms/pseries/hotplug-cpu.c@@ -802,6 +802,25 @@ static int dlpar_cpu_add_by_count(u32 cpus_to_add) 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) { u32 count, drc_index;