Messages in this thread Patch in this message | | | Subject | Re: WARNING: CPU: 1 PID: 15 at kernel/sched/sched.h:804 assert_clock_updated.isra.62.part.63+0x25/0x27 | From | Mike Galbraith <> | Date | Tue, 31 Jan 2017 07:19:29 +0100 |
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On Mon, 2017-01-30 at 11:59 +0000, Matt Fleming wrote: > On Sat, 28 Jan, at 08:21:05AM, Mike Galbraith wrote: > > Running Steven's hotplug stress script in tip.today. Config is > > NOPREEMPT, tune for maximum build time (enterprise default-ish). > > > > [ 75.268049] x86: Booting SMP configuration: > > [ 75.268052] smpboot: Booting Node 0 Processor 1 APIC 0x2 > > [ 75.279994] smpboot: Booting Node 0 Processor 2 APIC 0x4 > > [ 75.294617] smpboot: Booting Node 0 Processor 4 APIC 0x1 > > [ 75.310698] smpboot: Booting Node 0 Processor 5 APIC 0x3 > > [ 75.359056] smpboot: CPU 3 is now offline > > [ 75.415505] smpboot: CPU 4 is now offline > > [ 75.479985] smpboot: CPU 5 is now offline > > [ 75.550674] ------------[ cut here ]------------ > > [ 75.550678] WARNING: CPU: 1 PID: 15 at kernel/sched/sched.h:804 > > assert_clock_updated.isra.62.part.63+0x25/0x27 > > [ 75.550679] rq->clock_update_flags < RQCF_ACT_SKIP > > The following patch queued in tip/sched/core should fix this issue:
Weeell, I'll have to take your word for it, as tip g35669bb7fd46 grew an early boot brick problem.
> ---->8---- > > From 4d25b35ea3729affd37d69c78191ce6f92766e1a Mon Sep 17 00:00:00 > 2001 > From: Matt Fleming <matt@codeblueprint.co.uk> > Date: Wed, 26 Oct 2016 16:15:44 +0100 > Subject: [PATCH] sched/fair: Restore previous rq_flags when migrating > tasks in > hotplug > > __migrate_task() can return with a different runqueue locked than the > one we passed as an argument. So that we can repin the lock in > migrate_tasks() (and keep the update_rq_clock() bit) we need to > restore the old rq_flags before repinning. > > Note that it wouldn't be correct to change move_queued_task() to > repin > because of the change of runqueue and the fact that having an > up-to-date clock on the initial rq doesn't mean the new rq has one > too. > > Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk> > Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> > Cc: Linus Torvalds <torvalds@linux-foundation.org> > Cc: Mike Galbraith <efault@gmx.de> > Cc: Peter Zijlstra <peterz@infradead.org> > Cc: Thomas Gleixner <tglx@linutronix.de> > Signed-off-by: Ingo Molnar <mingo@kernel.org> > --- > kernel/sched/core.c | 10 +++++++++- > 1 file changed, 9 insertions(+), 1 deletion(-) > > diff --git a/kernel/sched/core.c b/kernel/sched/core.c > index 7f983e83a353..3b248b03ad8f 100644 > --- a/kernel/sched/core.c > +++ b/kernel/sched/core.c > @@ -5608,7 +5608,7 @@ static void migrate_tasks(struct rq *dead_rq) > { > struct rq *rq = dead_rq; > struct task_struct *next, *stop = rq->stop; > - struct rq_flags rf; > + struct rq_flags rf, old_rf; > int dest_cpu; > > /* > @@ -5669,6 +5669,13 @@ static void migrate_tasks(struct rq *dead_rq) > continue; > } > > + /* > + * __migrate_task() may return with a different > + * rq->lock held and a new cookie in 'rf', but we > need > + * to preserve rf::clock_update_flags for 'dead_rq'. > + */ > + old_rf = rf; > + > /* Find suitable destination for @next, with force > if needed. */ > dest_cpu = select_fallback_rq(dead_rq->cpu, next); > > @@ -5677,6 +5684,7 @@ static void migrate_tasks(struct rq *dead_rq) > raw_spin_unlock(&rq->lock); > rq = dead_rq; > raw_spin_lock(&rq->lock); > + rf = old_rf; > } > raw_spin_unlock(&next->pi_lock); > }
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