| Message ID | alpine.DEB.2.11.1505071425520.4225@nanos (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Hi Thomas, On Thu, May 07, 2015 at 02:35:59PM +0200, Thomas Gleixner wrote: > On Thu, 7 May 2015, Simon Horman wrote: > > ------------[ cut here ]------------ > > kernel BUG at kernel/irq_work.c:135! > > BUG_ON(!irqs_disabled()); > > So something enables interrupts in the periodic tick handling > machinery. Seems you have high resolution timers disabled, but nohz > enabled. And that code path has a local_irq_disable/enable pair which > causes havoc. Patch below. Thanks for your quick response. I have been able to confirm that when applied on top of next-20150507 the problem I observed no longer manifests. I have successfully tested it on all the boards where I previously observed a problem. If you are planning to formally submit the patch below feel free to add: Tested-by: Simon Horman <horms+renesas@verge.net.au> > diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c > index 753c211f6195..812f7a3b9898 100644 > --- a/kernel/time/tick-sched.c > +++ b/kernel/time/tick-sched.c > @@ -967,11 +967,9 @@ static void tick_nohz_switch_to_nohz(void) > if (!tick_nohz_enabled) > return; > > - local_irq_disable(); > - if (tick_switch_to_oneshot(tick_nohz_handler)) { > - local_irq_enable(); > + if (tick_switch_to_oneshot(tick_nohz_handler)) > return; > - } > + > tick_nohz_active = 1; > ts->nohz_mode = NOHZ_MODE_LOWRES; > > @@ -986,7 +984,6 @@ static void tick_nohz_switch_to_nohz(void) > hrtimer_forward_now(&ts->sched_timer, tick_period); > hrtimer_set_expires(&ts->sched_timer, next); > tick_program_event(next, 1); > - local_irq_enable(); > } > > /* > @@ -1171,7 +1168,7 @@ void tick_oneshot_notify(void) > * Called cyclic from the hrtimer softirq (driven by the timer > * softirq) allow_nohz signals, that we can switch into low-res nohz > * mode, because high resolution timers are disabled (either compile > - * or runtime). > + * or runtime). Called with interrupts disabled. > */ > int tick_check_oneshot_change(int allow_nohz) > { > > > > > > _______________________________________________ > linux-arm-kernel mailing list > linux-arm-kernel@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel >
Simon Horman <horms@verge.net.au> writes: > Hi Thomas, > > On Thu, May 07, 2015 at 02:35:59PM +0200, Thomas Gleixner wrote: >> On Thu, 7 May 2015, Simon Horman wrote: >> > ------------[ cut here ]------------ >> > kernel BUG at kernel/irq_work.c:135! >> >> BUG_ON(!irqs_disabled()); >> >> So something enables interrupts in the periodic tick handling >> machinery. Seems you have high resolution timers disabled, but nohz >> enabled. And that code path has a local_irq_disable/enable pair which >> causes havoc. Patch below. > > Thanks for your quick response. I have been able to confirm that > when applied on top of next-20150507 the problem I observed no longer > manifests. I have successfully tested it on all the boards > where I previously observed a problem. > > If you are planning to formally submit the patch below feel free to add: > > Tested-by: Simon Horman <horms+renesas@verge.net.au> FWIW, I confirmed this fixed a boot hang on my kzm9d in next-20150507 also. Tested-by: Kevin Hilman <khilman@linaro.org>
diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c index 753c211f6195..812f7a3b9898 100644 --- a/kernel/time/tick-sched.c +++ b/kernel/time/tick-sched.c @@ -967,11 +967,9 @@ static void tick_nohz_switch_to_nohz(void) if (!tick_nohz_enabled) return; - local_irq_disable(); - if (tick_switch_to_oneshot(tick_nohz_handler)) { - local_irq_enable(); + if (tick_switch_to_oneshot(tick_nohz_handler)) return; - } + tick_nohz_active = 1; ts->nohz_mode = NOHZ_MODE_LOWRES; @@ -986,7 +984,6 @@ static void tick_nohz_switch_to_nohz(void) hrtimer_forward_now(&ts->sched_timer, tick_period); hrtimer_set_expires(&ts->sched_timer, next); tick_program_event(next, 1); - local_irq_enable(); } /* @@ -1171,7 +1168,7 @@ void tick_oneshot_notify(void) * Called cyclic from the hrtimer softirq (driven by the timer * softirq) allow_nohz signals, that we can switch into low-res nohz * mode, because high resolution timers are disabled (either compile - * or runtime). + * or runtime). Called with interrupts disabled. */ int tick_check_oneshot_change(int allow_nohz) {