Re: Regression with suspicious RCU usage splats with cpu_pm change

From: Paul E. McKenney
Date: Thu Jul 13 2017 - 08:43:57 EST


On Thu, Jul 13, 2017 at 01:50:26PM +0200, Rafael J. Wysocki wrote:
> On Thu, Jul 13, 2017 at 11:43 AM, Alex Shi <alex.shi@xxxxxxxxxx> wrote:
> >
> > On 07/13/2017 03:07 PM, Tony Lindgren wrote:
> >> Hi,
> >>
> >> Looks like next-20170713 gives me a bunch of "suspicious RCU usage"
> >> splats with cpuidle_coupled on duovero, see below. I bisected it down
> >> to commit 2f027e003d05 ("cpu_pm: replace raw_notifier with
> >> atomic_notifier").
>
> OK, so I'm dropping this commit.

You can surround idle-loop RCU-reading code with RCU_NONIDLE().
This will tell RCU to pay attention even though the CPU is otherwise
idle.

Thanx, Paul