Re: [linus:master] [sched/pelt] 97450eb909: INFO:task_blocked_for_more_than#seconds

[Chen Yu]

On 2024-07-09 at 12:03:42 +0200, Vincent Guittot wrote:
> On Tue, 9 Jul 2024 at 09:22, kernel test robot <oliver.sang@xxxxxxxxx> wrote:
> >
> >
> >
> > Hello,
> >
> > kernel test robot noticed "INFO:task_blocked_for_more_than#seconds" on:
> >
> > commit: 97450eb909658573dcacc1063b06d3d08642c0c1 ("sched/pelt: Remove shift of thermal clock")
> > https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git master
> 
> First, I'm surprised that an Intel platform is impacted by this patch
> because Intel doesn't use it AFAIK.
> Then, this patch mainly remove a right shift i.e.:
> instead of:
>   return rq_clock_task(rq) >> sched_hw_decay_shift
> we are now doing:
>   return rq_clock_task(rq)
> 
> Could it be a false positive ?

Before trying to reproduce it locally, one question is that, should we use
rq_clock_task(rq) in __update_blocked_others() rather than 'now', which is
actually calculated by rq_clock_pelt(rq)? 

thanks,
Chenyu

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index d34f6d5b11b5..17ec0c51b29d 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -9432,7 +9432,7 @@ static bool __update_blocked_others(struct rq *rq, bool *done)
 
 	decayed = update_rt_rq_load_avg(now, rq, curr_class == &rt_sched_class) |
 		  update_dl_rq_load_avg(now, rq, curr_class == &dl_sched_class) |
-		  update_hw_load_avg(now, rq, hw_pressure) |
+		  update_hw_load_avg(rq_clock_task(rq), rq, hw_pressure) |
 		  update_irq_load_avg(rq, 0);
 
 	if (others_have_blocked(rq))
-- 
2.25.1