Re: [BUG][next-20170606][bisected 411fe24e6b] WARNING: CPU: 10 PID: 0 at kernel/time/tick-sched.c:791

[Frederic Weisbecker]

On Wed, Jun 07, 2017 at 12:56:53PM +0530, Abdul Haleem wrote:
> Hi,
> 
> Test: Trinity (https://github.com/kernelslacker/trinity)
> Machine : Power 8 PowerVM LPAR
> Kernel : 4.12.0-rc4-next-20170606
> gcc : version 5.2.1
> config : attached
> 
> With commit (411fe24e6b : nohz: Fix collision between tick and other
> hrtimers), a WARNING is seen while running trinity syscall fuzzer
> 
> In file kernel/time/tick-sched.c at line 791, a WARN_ON_ONCE is being
> triggered from tick_nohz_stop_sched_tick function.
> 
>     /* Skip reprogram of event if its not changed */
>     if (ts->tick_stopped && (expires == ts->next_tick)) {
>         /* Sanity check: make sure clockevent is actually programmed */
>         if (likely(dev->next_event <= ts->next_tick))
>             goto out;
> 
>         WARN_ON_ONCE(1);
>         printk_once("basemono: %llu ts->next_tick: %llu dev->next_event: %llu timer->active: %d timer->expires: %llu\n",
>                 basemono, ts->next_tick, dev->next_event,
>                 hrtimer_active(&ts->sched_timer), hrtimer_get_expires(&ts->sched_timer));
>     }
> 
> Trace logs:
> [22934.302780] ------------[ cut here ]------------
> [22934.302787] WARNING: CPU: 10 PID: 0 at kernel/time/tick-sched.c:791
> __tick_nohz_idle_enter+0x2e8/0x570

Hi Abdul,

Thanks for reporting. I've cooked a fix, any chance you could test it?

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