Messages in this thread | | | Date | Fri, 19 Jun 2015 18:30:08 +0200 (CEST) | From | Thomas Gleixner <> | Subject | Re: [-next] !irqd_can_balance() WARNINGs at irq_move_masked_irq() |
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On Sat, 20 Jun 2015, Jiang Liu wrote: > On 2015/6/20 0:15, Thomas Gleixner wrote: > > On Sat, 20 Jun 2015, Jiang Liu wrote: > > > >> [...] > >>>> Something in the kernel (not yet clear what) tries to move the hpet > >>>> irq 0 by calling irq_set_affinity(). That's an kernel internal > >>>> interface which does not check whether the NO BALANCE flag is set for > >>>> the irq. So the call runs and triggers the move from next interrupt > >>>> machinery which ends up calling irq_move_masked_irq() and that trips > >>>> over the flag and yells. > >>>> > >>>> That's why I changed the WARN to a pr_warn() because we already know > >>>> the call stack. > >>>> > >>>> So the core behaviour is inconsistent. We let the caller of > >>>> irq_set_affinity() succeed and yell later because we think it's wrong. > >>>> > >>>> I'm pretty sure that we must drop the check for NO BALANCE in > >>>> irq_move_masked_irq() and only check for the per_cpu bit, but at the > >>>> same time I really want to know where that call to irq_set_affinity(irq0) > >>>> is coming from. > >>>> > >>>> Can you please collect the output of /proc/timer_list for the previous > >>>> patch and then replace the previous patch with the one below and > >>>> gather all the data again? > >>> > >>> Hi Thomas, > >>> Maybe it's caused by the hpet driver itself? > >>> irq_set_affinity() may set the IRQD_SETAFFINITY_PENDING flag, > >>> thus triggering the warning. > >> And the usage pattern seems reasonable, the IRQF_NOBALANCING flag > >> means nobody may change the affinity except myself:) > > > > Right, that's why I removed the restriction. I just wonder why we have > > not seen that before ... > I suspected it's caused by the hierarchy irqdomain at first glance > because the multiple irq_datas issue, but seems it's not after checking > the code. It will only be triggered if HPET works in MSI mode instead of > legacy IRQ mode, but still need more investigation here.
Right. And what confuses me is that this happens on irq0, which is ioapic edge.
Thanks,
tglx
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