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.
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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