Re: [PATCH v2] sched/fair: Fix fault in reweight_entity

[Tadeusz Struk <tadeusz.struk@linaro.org>]

On 1/25/22 10:30, Tadeusz Struk wrote:
> On 1/25/22 01:14, Vincent Guittot wrote:
>> Could we use :
>> set_load_weight(p, !(p->__state & TASK_NEW));
>> instead of
>> set_load_weight(p, true);
>> in set_user_nice and __setscheduler_params.
> 
> Wouldn't that require READ_ONCE() and rmb() after the read?

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 848eaa0efe0e..3d7ede06b971 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -6921,7 +6921,7 @@ void set_user_nice(struct task_struct *p, long nice)
                 put_prev_task(rq, p);

         p->static_prio = NICE_TO_PRIO(nice);
-       set_load_weight(p, true);
+       set_load_weight(p, !(READ_ONCE(p->__state) & TASK_NEW));
         old_prio = p->prio;
         p->prio = effective_prio(p);

That works for me. I will send a new version soon.

-- 
Thanks,
Tadeusz