| From foo@baz Sun May 27 17:33:38 CEST 2018 |
| From: Davidlohr Bueso <dave@stgolabs.net> |
| Date: Mon, 2 Apr 2018 09:49:54 -0700 |
| Subject: sched/rt: Fix rq->clock_update_flags < RQCF_ACT_SKIP warning |
| |
| From: Davidlohr Bueso <dave@stgolabs.net> |
| |
| [ Upstream commit d29a20645d5e929aa7e8616f28e5d8e1c49263ec ] |
| |
| While running rt-tests' pi_stress program I got the following splat: |
| |
| rq->clock_update_flags < RQCF_ACT_SKIP |
| WARNING: CPU: 27 PID: 0 at kernel/sched/sched.h:960 assert_clock_updated.isra.38.part.39+0x13/0x20 |
| |
| [...] |
| |
| <IRQ> |
| enqueue_top_rt_rq+0xf4/0x150 |
| ? cpufreq_dbs_governor_start+0x170/0x170 |
| sched_rt_rq_enqueue+0x65/0x80 |
| sched_rt_period_timer+0x156/0x360 |
| ? sched_rt_rq_enqueue+0x80/0x80 |
| __hrtimer_run_queues+0xfa/0x260 |
| hrtimer_interrupt+0xcb/0x220 |
| smp_apic_timer_interrupt+0x62/0x120 |
| apic_timer_interrupt+0xf/0x20 |
| </IRQ> |
| |
| [...] |
| |
| do_idle+0x183/0x1e0 |
| cpu_startup_entry+0x5f/0x70 |
| start_secondary+0x192/0x1d0 |
| secondary_startup_64+0xa5/0xb0 |
| |
| We can get rid of it be the "traditional" means of adding an |
| update_rq_clock() call after acquiring the rq->lock in |
| do_sched_rt_period_timer(). |
| |
| The case for the RT task throttling (which this workload also hits) |
| can be ignored in that the skip_update call is actually bogus and |
| quite the contrary (the request bits are removed/reverted). |
| |
| By setting RQCF_UPDATED we really don't care if the skip is happening |
| or not and will therefore make the assert_clock_updated() check happy. |
| |
| Signed-off-by: Davidlohr Bueso <dbueso@suse.de> |
| Reviewed-by: Matt Fleming <matt@codeblueprint.co.uk> |
| Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> |
| Cc: Linus Torvalds <torvalds@linux-foundation.org> |
| Cc: Mike Galbraith <efault@gmx.de> |
| Cc: Thomas Gleixner <tglx@linutronix.de> |
| Cc: dave@stgolabs.net |
| Cc: linux-kernel@vger.kernel.org |
| Cc: rostedt@goodmis.org |
| Link: http://lkml.kernel.org/r/20180402164954.16255-1-dave@stgolabs.net |
| Signed-off-by: Ingo Molnar <mingo@kernel.org> |
| Signed-off-by: Sasha Levin <alexander.levin@microsoft.com> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| --- |
| kernel/sched/rt.c | 2 ++ |
| 1 file changed, 2 insertions(+) |
| |
| --- a/kernel/sched/rt.c |
| +++ b/kernel/sched/rt.c |
| @@ -830,6 +830,8 @@ static int do_sched_rt_period_timer(stru |
| struct rq *rq = rq_of_rt_rq(rt_rq); |
| |
| raw_spin_lock(&rq->lock); |
| + update_rq_clock(rq); |
| + |
| if (rt_rq->rt_time) { |
| u64 runtime; |
| |