Re: [PATCH] kfence: use TASK_IDLE when awaiting allocation

[Marco Elver]

On Fri, 21 May 2021 at 11:37, Hillf Danton <hdanton@xxxxxxxx> wrote:
> On Fri, 21 May 2021 10:32:09 +0200 Marco Elver wrote:
> >Since wait_event() uses TASK_UNINTERRUPTIBLE by default, waiting for an
> >allocation counts towards load. However, for KFENCE, this does not make
> >any sense, since there is no busy work we're awaiting.
>
> Because of a blocking wq callback, kfence_timer should be queued on a
> unbound workqueue in the first place. Feel free to add a followup to
> replace system_power_efficient_wq with system_unbound_wq if it makes
> sense to you that kfence behaves as correctly as expected independent of
> CONFIG_WQ_POWER_EFFICIENT_DEFAULT given "system_power_efficient_wq is
> identical to system_wq if 'wq_power_efficient' is disabled."

Thanks for pointing it out -- I think this makes sense, let's just use
the unbound wq unconditionally. Since it's independent of this patch,
I've sent it separately:
https://lkml.kernel.org/r/20210521111630.472579-1-elver@xxxxxxxxxx