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    SubjectRe: [PATCH v2 tip/core/rcu 01/10] rcu: Add call_rcu_tasks()
    On Fri, Aug 01, 2014 at 05:53:10PM +0200, Oleg Nesterov wrote:
    > On 07/30, Paul E. McKenney wrote:
    > >
    > > + rcu_read_lock();
    > > + for_each_process_thread(g, t) {
    > > + if (t != current && ACCESS_ONCE(t->on_rq) &&
    > > + !is_idle_task(t)) {
    > > + t->rcu_tasks_nvcsw = ACCESS_ONCE(t->nvcsw);
    > > + t->rcu_tasks_holdout = 1;
    > > + list_add(&t->rcu_tasks_holdout_list,
    > > + &rcu_tasks_holdouts);
    > > + }
    > > + }
    > > + rcu_read_unlock();
    >
    > Wait, unless I missed something this can't work...
    >
    > The problem is, once the exiting task passes exit_notify() it can
    > be removed from rcu lists.
    >
    > Now suppose that (say) proc_exit_connector() has a probe, and this
    > task has jumped into trampoline and it was preempted there.
    >
    > No?

    OK, this sounds to me like another vote for get_task_struct() as used
    in the v3 series. Or am I missing something?

    Thanx, Paul



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