sched/fair: Fixes for capacity inversion detection

commit da07d2f9c1 upstream.

Traversing the Perf Domains requires rcu_read_lock() to be held and is
conditional on sched_energy_enabled(). Ensure right protections applied.

Also skip capacity inversion detection for our own pd; which was an
error.

Fixes: 44c7b80bff ("sched/fair: Detect capacity inversion")
Reported-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Signed-off-by: Qais Yousef (Google) <qyousef@layalina.io>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lore.kernel.org/r/20230112122708.330667-3-qyousef@layalina.io
(cherry picked from commit da07d2f9c1)
Signed-off-by: Qais Yousef (Google) <qyousef@layalina.io>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Qais Yousef 2023-04-18 15:05:47 +01:00 committed by Justin Hammond
parent feefbb68b4
commit ff4d9e519c

View file

@ -8649,16 +8649,23 @@ static void update_cpu_capacity(struct sched_domain *sd, int cpu)
* * Thermal pressure will impact all cpus in this perf domain
* equally.
*/
if (static_branch_unlikely(&sched_asym_cpucapacity)) {
if (sched_energy_enabled()) {
unsigned long inv_cap = capacity_orig - thermal_load_avg(rq);
struct perf_domain *pd = rcu_dereference(rq->rd->pd);
struct perf_domain *pd;
rcu_read_lock();
pd = rcu_dereference(rq->rd->pd);
rq->cpu_capacity_inverted = 0;
for (; pd; pd = pd->next) {
struct cpumask *pd_span = perf_domain_span(pd);
unsigned long pd_cap_orig, pd_cap;
/* We can't be inverted against our own pd */
if (cpumask_test_cpu(cpu_of(rq), pd_span))
continue;
cpu = cpumask_any(pd_span);
pd_cap_orig = arch_scale_cpu_capacity(cpu);
@ -8683,6 +8690,8 @@ static void update_cpu_capacity(struct sched_domain *sd, int cpu)
break;
}
}
rcu_read_unlock();
}
trace_sched_cpu_capacity_tp(rq);