On Mon, Jun 12, 2023 at 04:51:17PM +0300, Dan Carpenter wrote:
> On Mon, Jun 12, 2023 at 11:07:22AM +0200, Peter Zijlstra wrote:
> > --- a/kernel/sched/core.c
> > +++ b/kernel/sched/core.c
> > @@ -3664,16 +3664,15 @@ ttwu_stat(struct task_struct *p, int cpu
> > __schedstat_inc(p->stats.nr_wakeups_local);
> > } else {
> > struct sched_domain *sd;
> > + guard(rcu)();
> >
> > __schedstat_inc(p->stats.nr_wakeups_remote);
> > - rcu_read_lock();
>
> We can't put the guard(rcu)(); here? I have unpublished static analysis
> which assumes that the first and last statements guarded by a lock are
> important. But if we always put it at the top of the scope then we
> lose that information.
we can definitely put it there. that one schedstat doesn't matter either
way around.
> > for_each_domain(rq->cpu, sd) {
> > if (cpumask_test_cpu(cpu, sched_domain_span(sd))) {
> > __schedstat_inc(sd->ttwu_wake_remote);
> > break;
> > }
> > }
> > - rcu_read_unlock();
> > }
