powerpc/pseries: Perform full re-add of CPU for topology update post-migration (81b61324) · Commits · 戴 / test

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 <nfont@linux.vnet.ibm.com> Signed-off-by:

Michael W. Bringmann <mwb@linux.vnet.ibm.com> Tested-by:

Michael W. Bringmann <mwb@linux.vnet.ibm.com> Signed-off-by:

Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/include/asm/topology.h

+2 −0

Original line number	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_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

arch/powerpc/mm/numa.c

+1 −8

Original line number	Diff line number	Diff line
		@@ -1460,13 +1460,6 @@ 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)
		{
		@@ -1479,7 +1472,7 @@ 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;

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

+19 −0

Original line number	Diff line number	Diff line
		@@ -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;

Admin message