[GIT PULL] scheduler fixes

Ingo Molnar
2019-11-01T17:55:15Z

Linus,

Please pull the latest sched-urgent-for-linus git tree from:

git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git sched-urgent-for-linus

# HEAD: e284df705cf1eeedb5ec3a66ed82d17a64659150 sched/topology: Allow sched_asym_cpucapacity to be disabled

Fix two scheduler topology bugs/oversights on Juno r0 2+4 big.LITTLE
systems.

Thanks,

Ingo

------------------>
Valentin Schneider (2):
sched/topology: Don't try to build empty sched domains
sched/topology: Allow sched_asym_cpucapacity to be disabled

kernel/cgroup/cpuset.c | 3 ++-
kernel/sched/topology.c | 11 +++++++++--
2 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
index c52bc91f882b..c87ee6412b36 100644
--- a/kernel/cgroup/cpuset.c
+++ b/kernel/cgroup/cpuset.c
@@ -798,7 +798,8 @@ static int generate_sched_domains(cpumask_var_t **domains,
cpumask_subset(cp->cpus_allowed, top_cpuset.effective_cpus))
continue;

- if (is_sched_load_balance(cp))
+ if (is_sched_load_balance(cp) &&
+ !cpumask_empty(cp->effective_cpus))
csa[csn++] = cp;

/* skip @cp's subtree if not a partition root */
diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c
index b5667a273bf6..49b835f1305f 100644
--- a/kernel/sched/topology.c
+++ b/kernel/sched/topology.c
@@ -1948,7 +1948,7 @@ static struct sched_domain_topology_level
static int
build_sched_domains(const struct cpumask *cpu_map, struct sched_domain_attr *attr)
{
- enum s_alloc alloc_state;
+ enum s_alloc alloc_state = sa_none;
struct sched_domain *sd;
struct s_data d;
struct rq *rq = NULL;
@@ -1956,6 +1956,9 @@ build_sched_domains(const struct cpumask *cpu_map, struct sched_domain_attr *att
struct sched_domain_topology_level *tl_asym;
bool has_asym = false;

+ if (WARN_ON(cpumask_empty(cpu_map)))
+ goto error;
+
alloc_state = __visit_domain_allocation_hell(&d, cpu_map);
if (alloc_state != sa_rootdomain)
goto error;
@@ -2026,7 +2029,7 @@ build_sched_domains(const struct cpumask *cpu_map, struct sched_domain_attr *att
rcu_read_unlock();

if (has_asym)
- static_branch_enable_cpuslocked(&sched_asym_cpucapacity);
+ static_branch_inc_cpuslocked(&sched_asym_cpucapacity);

if (rq && sched_debug_enabled) {
pr_info("root domain span: %*pbl (max cpu_capacity = %lu)\n",
@@ -2121,8 +2124,12 @@ int sched_init_domains(const struct cpumask *cpu_map)
*/
static void detach_destroy_domains(const struct cpumask *cpu_map)
{
+ unsigned int cpu = cpumask_any(cpu_map);
int i;

+ if (rcu_access_pointer(per_cpu(sd_asym_cpucapacity, cpu)))
+ static_branch_dec_cpuslocked(&sched_asym_cpucapacity);
+
rcu_read_lock();
for_each_cpu(i, cpu_map)
cpu_attach_domain(NULL, &def_root_domain, i);