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 I have unpublished static analysis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.
> 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();
> }
regards,
dan carpenter
