On Fri, Jul 28, 2017 at 03:38:15PM +0000, Mathieu Desnoyers wrote: > > Which only leaves PPC stranded.. but the 'good' news is that mpe says > > they'll probably need a barrier in switch_mm() in any case. > > As I pointed out in my other email, I plan to do this: > > --- a/kernel/sched/core.c > +++ b/kernel/sched/core.c > @@ -2636,6 +2636,11 @@ static struct rq *finish_task_switch(struct > task_struct *prev) > vtime_task_switch(prev); > perf_event_task_sched_in(prev, current);
Here would place it _inside_ the rq->lock, which seems to make more sense given the purpose of the barrier, but either way works given its definition. > finish_lock_switch(rq, prev); You could put the whole thing inside IS_ENABLED(CONFIG_SYSMEMBARRIER) or something. > + /* > + * The membarrier system call requires a full memory barrier > + * after storing to rq->curr, before going back to user-space. > + */ > + smp_mb__after_unlock_lock(); > finish_arch_post_lock_switch(); > > fire_sched_in_preempt_notifiers(current);
