On 04/28, Peter Zijlstra wrote:
>
> On Thu, Apr 28, 2022 at 04:57:50PM +0200, Oleg Nesterov wrote:
>
> > > Shouldn't we then switch wait_task_inactive() so have & matching instead
> > > of the current ==.
> >
> > Sorry, I don't understand the context...
>
> This.. I've always found it strange to have wti use a different matching
> scheme from ttwu.
Ah. This is what I understood (and I too thought about this), just I meant that
this patch from Eric (assuming wait_task_inactive() still uses __TASK_TRACED) is
fine without your change below.
Oleg.
> diff --git a/kernel/sched/core.c b/kernel/sched/core.c
> index f259621f4c93..c039aef4c8fe 100644
> --- a/kernel/sched/core.c
> +++ b/kernel/sched/core.c
> @@ -3304,7 +3304,7 @@ unsigned long wait_task_inactive(struct task_struct *p,
> unsigned int match_state
> * is actually now running somewhere else!
> */
> while (task_running(rq, p)) {
> - if (match_state && unlikely(READ_ONCE(p->__state) !=
> match_state))
> + if (match_state && unlikely(!(READ_ONCE(p->__state) &
> match_state)))
> return 0;
> cpu_relax();
> }
> @@ -3319,7 +3319,7 @@ unsigned long wait_task_inactive(struct task_struct *p,
> unsigned int match_state
> running = task_running(rq, p);
> queued = task_on_rq_queued(p);
> ncsw = 0;
> - if (!match_state || READ_ONCE(p->__state) == match_state)
> + if (!match_state || (READ_ONCE(p->__state) & match_state))
> ncsw = p->nvcsw | LONG_MIN; /* sets MSB */
> task_rq_unlock(rq, p, &rf);
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