On Mon, Sep 03, 2018 at 09:38:15AM +0200, Thomas Gleixner wrote: > 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 <schwidef...@de.ibm.com> > > > 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.
ARGH... OK, lemme see if I can come up with something other than endlessly spawning that kthread. A special purpose kthread_worker would make more sense than that.
