From: Tim Chen <tim.c.c...@linux.intel.com>
Current code can call set_cpu_sibling_map and invoke sched_set_topology
more than once (e.g. on hot plug). When this happens after
sched_init_smp has been called, we lose the numa topology extension to
sched_domain_topology in sched_init_numa. This results in incorrect
topology when the sched domain is rebuilt.
This patch fixes the bug and issues warning if we call sched_set_topology
after sched_init_smp.
Signed-off-by: Peter Zijlstra (Intel) <pet...@infradead.org>
Signed-off-by: Tim Chen <tim.c.c...@linux.intel.com>
Signed-off-by: Srinivas Pandruvada <srinivas.pandruv...@linux.intel.com>
---
arch/x86/kernel/smpboot.c | 46 ++++++++++++++++++++++++++++++----------------
kernel/sched/core.c | 3 +++
2 files changed, 33 insertions(+), 16 deletions(-)
diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index 4296beb..7137ec4 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -471,7 +471,7 @@ static bool match_die(struct cpuinfo_x86 *c, struct
cpuinfo_x86 *o)
return false;
}
-static struct sched_domain_topology_level numa_inside_package_topology[] = {
+static struct sched_domain_topology_level x86_numa_in_package_topology[] = {
#ifdef CONFIG_SCHED_SMT
{ cpu_smt_mask, cpu_smt_flags, SD_INIT_NAME(SMT) },
#endif
@@ -480,22 +480,23 @@ static struct sched_domain_topology_level
numa_inside_package_topology[] = {
#endif
{ NULL, },
};
+
+static struct sched_domain_topology_level x86_topology[] = {
+#ifdef CONFIG_SCHED_SMT
+ { cpu_smt_mask, cpu_smt_flags, SD_INIT_NAME(SMT) },
+#endif
+#ifdef CONFIG_SCHED_MC
+ { cpu_coregroup_mask, cpu_core_flags, SD_INIT_NAME(MC) },
+#endif
+ { cpu_cpu_mask, SD_INIT_NAME(DIE) },
+ { NULL, },
+};
+
/*
- * set_sched_topology() sets the topology internal to a CPU. The
- * NUMA topologies are layered on top of it to build the full
- * system topology.
- *
- * If NUMA nodes are observed to occur within a CPU package, this
- * function should be called. It forces the sched domain code to
- * only use the SMT level for the CPU portion of the topology.
- * This essentially falls back to relying on NUMA information
- * from the SRAT table to describe the entire system topology
- * (except for hyperthreads).
+ * Set if a package/die has multiple NUMA nodes inside.
+ * AMD Magny-Cours and Intel Cluster-on-Die have this.
*/
-static void primarily_use_numa_for_topology(void)
-{
- set_sched_topology(numa_inside_package_topology);
-}
+static bool x86_has_numa_in_package;
void set_cpu_sibling_map(int cpu)
{
@@ -558,7 +559,7 @@ void set_cpu_sibling_map(int cpu)
c->booted_cores = cpu_data(i).booted_cores;
}
if (match_die(c, o) && !topology_same_node(c, o))
- primarily_use_numa_for_topology();
+ x86_has_numa_in_package = true;
}
threads = cpumask_weight(topology_sibling_cpumask(cpu));
@@ -1304,6 +1305,16 @@ void __init native_smp_prepare_cpus(unsigned int
max_cpus)
zalloc_cpumask_var(&per_cpu(cpu_core_map, i), GFP_KERNEL);
zalloc_cpumask_var(&per_cpu(cpu_llc_shared_map, i), GFP_KERNEL);
}
+
+ /*
+ * Set 'default' x86 topology, this matches default_topology() in that
+ * it has NUMA nodes as a topology level. See also
+ * native_smp_cpus_done().
+ *
+ * Must be done before set_cpus_sibling_map() is ran.
+ */
+ set_sched_topology(x86_topology);
+
set_cpu_sibling_map(0);
switch (smp_sanity_check(max_cpus)) {
@@ -1370,6 +1381,9 @@ void __init native_smp_cpus_done(unsigned int max_cpus)
{
pr_debug("Boot done\n");
+ if (x86_has_numa_in_package)
+ set_sched_topology(x86_numa_in_package_topology);
+
nmi_selftest();
impress_friends();
setup_ioapic_dest();
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 2a906f2..e86c4a5 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -6487,6 +6487,9 @@ static struct sched_domain_topology_level
*sched_domain_topology =
void set_sched_topology(struct sched_domain_topology_level *tl)
{
+ if (WARN_ON_ONCE(sched_smp_initialized))
+ return;
+
sched_domain_topology = tl;
}
--
2.7.4
