On Mon, 3 Sep 2018, Peter Zijlstra wrote:
> On Sat, Sep 01, 2018 at 11:51:26AM +0930, Kevin Shanahan wrote:
> > commit 01548f4d3e8e94caf323a4f664eb347fd34a34ab
> > Author: Martin Schwidefsky <[email protected]>
> > Date: Tue Aug 18 17:09:42 2009 +0200
> >
> > clocksource: Avoid clocksource watchdog circular locking dependency
> >
> > stop_machine from a multithreaded workqueue is not allowed because
> > of a circular locking dependency between cpu_down and the workqueue
> > execution. Use a kernel thread to do the clocksource downgrade.
>
> I cannot find stop_machine usage there; either it went away or I need to
> like wake up.
timekeeping_notify() which is involved in switching clock source uses stomp
machine.
Thanks,
tglx
