aboutsummaryrefslogtreecommitdiff
path: root/arch/powerpc
diff options
context:
space:
mode:
authorRobert Jennings <rcj@linux.vnet.ibm.com>2013-07-24 20:13:21 -0500
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2013-08-11 18:35:20 -0700
commit027798707afb90e6f08144955813ba575743b04d (patch)
treed37f2935c3d25a060090a45079f4b37114985116 /arch/powerpc
parent8148d0952b58d0664c3a3ddffbe6ded35ad4c790 (diff)
downloadlinaro-lsk-027798707afb90e6f08144955813ba575743b04d.tar.gz
powerpc: VPHN topology change updates all siblings
commit 3be7db6ab45b21345386d1a466da133b19cde5e4 upstream. When an associativity level change is found for one thread, the siblings threads need to be updated as well. This is done today for PRRN in stage_topology_update() but is missing for VPHN in update_cpu_associativity_changes_mask(). This patch will correctly update all thread siblings during a topology change. Without this patch a topology update can result in a CPU in init_sched_groups_power() getting stuck indefinitely in a loop. This loop is built in build_sched_groups(). As a result of the thread moving to a node separate from its siblings the struct sched_group will have its next pointer set to point to itself rather than the sched_group struct of the next thread. This happens because we have a domain without the SD_OVERLAP flag, which is correct, and a topology that doesn't conform with reality (threads on the same core assigned to different numa nodes). When this list is traversed by init_sched_groups_power() it will reach the thread's sched_group structure and loop indefinitely; the cpu will be stuck at this point. The bug was exposed when VPHN was enabled in commit b7abef0 (v3.9). Reported-by: Jan Stancek <jstancek@redhat.com> Signed-off-by: Robert Jennings <rcj@linux.vnet.ibm.com> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'arch/powerpc')
-rw-r--r--arch/powerpc/include/asm/smp.h4
-rw-r--r--arch/powerpc/mm/numa.c59
2 files changed, 48 insertions, 15 deletions
diff --git a/arch/powerpc/include/asm/smp.h b/arch/powerpc/include/asm/smp.h
index ffbaabebcdc..48cfc858abd 100644
--- a/arch/powerpc/include/asm/smp.h
+++ b/arch/powerpc/include/asm/smp.h
@@ -145,6 +145,10 @@ extern void __cpu_die(unsigned int cpu);
#define smp_setup_cpu_maps()
static inline void inhibit_secondary_onlining(void) {}
static inline void uninhibit_secondary_onlining(void) {}
+static inline const struct cpumask *cpu_sibling_mask(int cpu)
+{
+ return cpumask_of(cpu);
+}
#endif /* CONFIG_SMP */
diff --git a/arch/powerpc/mm/numa.c b/arch/powerpc/mm/numa.c
index 2859a1f5227..cafad401776 100644
--- a/arch/powerpc/mm/numa.c
+++ b/arch/powerpc/mm/numa.c
@@ -27,6 +27,7 @@
#include <linux/seq_file.h>
#include <linux/uaccess.h>
#include <linux/slab.h>
+#include <asm/cputhreads.h>
#include <asm/sparsemem.h>
#include <asm/prom.h>
#include <asm/smp.h>
@@ -1319,7 +1320,8 @@ static int update_cpu_associativity_changes_mask(void)
}
}
if (changed) {
- cpumask_set_cpu(cpu, changes);
+ cpumask_or(changes, changes, cpu_sibling_mask(cpu));
+ cpu = cpu_last_thread_sibling(cpu);
}
}
@@ -1427,7 +1429,7 @@ static int update_cpu_topology(void *data)
if (!data)
return -EINVAL;
- cpu = get_cpu();
+ cpu = smp_processor_id();
for (update = data; update; update = update->next) {
if (cpu != update->cpu)
@@ -1447,12 +1449,12 @@ static int update_cpu_topology(void *data)
*/
int arch_update_cpu_topology(void)
{
- unsigned int cpu, changed = 0;
+ unsigned int cpu, sibling, changed = 0;
struct topology_update_data *updates, *ud;
unsigned int associativity[VPHN_ASSOC_BUFSIZE] = {0};
cpumask_t updated_cpus;
struct device *dev;
- int weight, i = 0;
+ int weight, new_nid, i = 0;
weight = cpumask_weight(&cpu_associativity_changes_mask);
if (!weight)
@@ -1465,19 +1467,46 @@ int arch_update_cpu_topology(void)
cpumask_clear(&updated_cpus);
for_each_cpu(cpu, &cpu_associativity_changes_mask) {
- ud = &updates[i++];
- ud->cpu = cpu;
- vphn_get_associativity(cpu, associativity);
- ud->new_nid = associativity_to_nid(associativity);
-
- if (ud->new_nid < 0 || !node_online(ud->new_nid))
- ud->new_nid = first_online_node;
+ /*
+ * If siblings aren't flagged for changes, updates list
+ * will be too short. Skip on this update and set for next
+ * update.
+ */
+ if (!cpumask_subset(cpu_sibling_mask(cpu),
+ &cpu_associativity_changes_mask)) {
+ pr_info("Sibling bits not set for associativity "
+ "change, cpu%d\n", cpu);
+ cpumask_or(&cpu_associativity_changes_mask,
+ &cpu_associativity_changes_mask,
+ cpu_sibling_mask(cpu));
+ cpu = cpu_last_thread_sibling(cpu);
+ continue;
+ }
- ud->old_nid = numa_cpu_lookup_table[cpu];
- cpumask_set_cpu(cpu, &updated_cpus);
+ /* Use associativity from first thread for all siblings */
+ vphn_get_associativity(cpu, associativity);
+ new_nid = associativity_to_nid(associativity);
+ if (new_nid < 0 || !node_online(new_nid))
+ new_nid = first_online_node;
+
+ if (new_nid == numa_cpu_lookup_table[cpu]) {
+ cpumask_andnot(&cpu_associativity_changes_mask,
+ &cpu_associativity_changes_mask,
+ cpu_sibling_mask(cpu));
+ cpu = cpu_last_thread_sibling(cpu);
+ continue;
+ }
- if (i < weight)
- ud->next = &updates[i];
+ for_each_cpu(sibling, cpu_sibling_mask(cpu)) {
+ ud = &updates[i++];
+ ud->cpu = sibling;
+ ud->new_nid = new_nid;
+ ud->old_nid = numa_cpu_lookup_table[sibling];
+ cpumask_set_cpu(sibling, &updated_cpus);
+ if (i < weight)
+ ud->next = &updates[i];
+ }
+ cpu = cpu_last_thread_sibling(cpu);
}
stop_machine(update_cpu_topology, &updates[0], &updated_cpus);