linux-kernel - Re: thinkpad x60: sound problems in 4.15-rc1 was Re: thinkpad x60: sound problems in 4.14.0-next-20171114

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Date:   Sun, 24 Dec 2017 08:16:01 -0800
From:   vcaputo@...garu.com
To:     Thomas Gleixner <tglx@...utronix.de>
Cc:     Pavel Machek <pavel@....cz>,
        linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: thinkpad x60: sound problems in 4.15-rc1 was Re: thinkpad x60:
 sound problems in 4.14.0-next-20171114

On Sat, Dec 23, 2017 at 09:33:37PM +0100, Thomas Gleixner wrote:
> On Sat, 23 Dec 2017, vcaputo@...garu.com wrote:
> > On Fri, Dec 22, 2017 at 09:37:01PM -0800, vcaputo@...garu.com wrote:
> > Added the following instrumentation:
> > 
> > diff --git a/arch/x86/kernel/apic/vector.c b/arch/x86/kernel/apic/vector.c
> > index 93edc2236282..7034eda4d494 100644
> > --- a/arch/x86/kernel/apic/vector.c
> > +++ b/arch/x86/kernel/apic/vector.c
> > @@ -228,6 +228,9 @@ static int __assign_irq_vector(int irq, struct apic_chip_data *d,
> >         cpumask_and(vector_searchmask, vector_searchmask, mask);
> >         BUG_ON(apic->cpu_mask_to_apicid(vector_searchmask, irqdata,
> >                                         &d->cfg.dest_apicid));
> > +
> > +       printk("allocated vector=%i maskfirst=%i\n", d->cfg.vector, cpumask_first(vector_searchmask));
> > +
> >         return 0;
> >  }
> >  
> > This is what I see:
> > 
> > Upon playing song in cmus (on AC power since boot):
> >  Dec 22 22:26:52 iridesce kernel: allocated vector=35 maskfirst=1
> > 
> > Yank AC:
> >  Dec 22 22:27:14 iridesce kernel: allocated vector=51 maskfirst=1
> >  Dec 22 22:27:15 iridesce kernel: do_IRQ: 0.35 No irq handler for vector
> > 
> > So CPU 0 vector 35 got an interrupt when maskfirst=1 for 35 as seen in
> > the added printk.
> > 
> > It seems like the affinity changes are assuming a strict adherence to
> > the CPU mask when the underlying hardware is treating it more as a hint.
> > Perhaps handlers still need to be maintained on all CPUs in a given apic
> > domain, regardless of what the masks are configured as, to cover these
> > situations.
> 
> That's odd. I'll have a look after the holidays.
> 

Ok, just FYI I've reproduced it on rc5 as well.

I may be offline a bit at the start of the new year, in case you've got
something for me to test and I'm unresponsive.

Regards,
Vito Caputo