| Message ID | 20230112122708.330667-3-qyousef@layalina.io |
|---|---|
| State | Accepted |
| Commit | da07d2f9c153e457e845d4dcfdd13568d71d18a4 |
| Headers | show |
| Series | Fixes for uclamp and capacity inversion detection | expand |
On Thu, 12 Jan 2023 at 13:27, Qais Yousef <qyousef@layalina.io> wrote: > > 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: 44c7b80bffc3 ("sched/fair: Detect capacity inversion") > Reported-by: Dietmar Eggemann <dietmar.eggemann@arm.com> > Signed-off-by: Qais Yousef (Google) <qyousef@layalina.io> Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org> > --- > kernel/sched/fair.c | 13 +++++++++++-- > 1 file changed, 11 insertions(+), 2 deletions(-) > > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c > index 5a8e75d4a17b..34239d3118f0 100644 > --- a/kernel/sched/fair.c > +++ b/kernel/sched/fair.c > @@ -8992,16 +8992,23 @@ 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); > > @@ -9026,6 +9033,8 @@ static void update_cpu_capacity(struct sched_domain *sd, int cpu) > break; > } > } > + > + rcu_read_unlock(); > } > > trace_sched_cpu_capacity_tp(rq); > -- > 2.25.1 >
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 5a8e75d4a17b..34239d3118f0 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -8992,16 +8992,23 @@ 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); @@ -9026,6 +9033,8 @@ static void update_cpu_capacity(struct sched_domain *sd, int cpu) break; } } + + rcu_read_unlock(); } trace_sched_cpu_capacity_tp(rq);
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: 44c7b80bffc3 ("sched/fair: Detect capacity inversion") Reported-by: Dietmar Eggemann <dietmar.eggemann@arm.com> Signed-off-by: Qais Yousef (Google) <qyousef@layalina.io> --- kernel/sched/fair.c | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-)