RCU lockup issues when CONFIG_SOFTLOCKUP_DETECTOR=n - any one else seeing this?

[Michael Ellerman]

"Paul E. McKenney" <paulmck at linux.vnet.ibm.com> writes:
...
>
> commit 33103e7b1f89ef432dfe3337d2a6932cdf5c1312
> Author: Paul E. McKenney <paulmck at linux.vnet.ibm.com>
> Date:   Mon Aug 14 08:54:39 2017 -0700
>
>     EXP: Trace tick return from tick_nohz_stop_sched_tick
>     
>     Signed-off-by: Paul E. McKenney <paulmck at linux.vnet.ibm.com>
>
> diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
> index c7a899c5ce64..7358a5073dfb 100644
> --- a/kernel/time/tick-sched.c
> +++ b/kernel/time/tick-sched.c
> @@ -817,6 +817,7 @@ static ktime_t tick_nohz_stop_sched_tick(struct tick_sched *ts,
>  	 * (not only the tick).
>  	 */
>  	ts->sleep_length = ktime_sub(dev->next_event, now);
> +	trace_printk("tick_nohz_stop_sched_tick: %lld\n", (tick - ktime_get()) / 1000);
>  	return tick;
>  }

Should I be seeing negative values? A small sample:

          <idle>-0     [015] d...  1602.039695: __tick_nohz_idle_enter: tick_nohz_stop_sched_tick: -1602250019
          <idle>-0     [009] d...  1602.039701: __tick_nohz_idle_enter: tick_nohz_stop_sched_tick: -1602250025
          <idle>-0     [007] d...  1602.039702: __tick_nohz_idle_enter: tick_nohz_stop_sched_tick: -1602250025
          <idle>-0     [048] d...  1602.039703: __tick_nohz_idle_enter: tick_nohz_stop_sched_tick: 9973
          <idle>-0     [006] d...  1602.039704: __tick_nohz_idle_enter: tick_nohz_stop_sched_tick: -1602250027
          <idle>-0     [001] d...  1602.039730: __tick_nohz_idle_enter: tick_nohz_stop_sched_tick: -1602250053
          <idle>-0     [008] d...  1602.039732: __tick_nohz_idle_enter: tick_nohz_stop_sched_tick: -1602250055
          <idle>-0     [006] d...  1602.049695: __tick_nohz_idle_enter: tick_nohz_stop_sched_tick: -1602260018
          <idle>-0     [009] d...  1602.049695: __tick_nohz_idle_enter: tick_nohz_stop_sched_tick: -1602260018
          <idle>-0     [001] d...  1602.049695: __tick_nohz_idle_enter: tick_nohz_stop_sched_tick: -1602260018


I have a full trace, I'll send it to you off-list.

cheers