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    SubjectRe: [PATCH 2/7] sched/fair: Add group_misfit_task load-balance type
    On Thu, Feb 15, 2018 at 04:20:49PM +0000, Morten Rasmussen wrote:
    > @@ -6733,9 +6758,12 @@ done: __maybe_unused
    > if (hrtick_enabled(rq))
    > hrtick_start_fair(rq, p);
    >
    > + update_misfit_status(p, rq);
    > +
    > return p;
    >
    > idle:
    > + update_misfit_status(NULL, rq);
    > new_tasks = idle_balance(rq, rf);
    >
    > /*

    So we set a point when picking a task (or tick). We clear said pointer
    when idle.

    > @@ -7822,6 +7855,10 @@ static inline void update_sg_lb_stats(struct lb_env *env,
    > */
    > if (!nr_running && idle_cpu(i))
    > sgs->idle_cpus++;
    > +
    > + if (env->sd->flags & SD_ASYM_CPUCAPACITY &&
    > + !sgs->group_misfit_task_load && rq->misfit_task_load)
    > + sgs->group_misfit_task_load = rq->misfit_task_load;
    > }
    >
    > /* Adjust by relative CPU capacity of the group */

    And we read said pointer from another CPU, without holding the
    respective rq->lock.

    What happens, if right after we set sgs->group_misfit_task_load, our
    task decides to exit?

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