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SubjectRe: [regression 4.14rc] 74def747bcd0 (genirq: Restrict effective affinity to interrupts actually using it)
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On Sun, 2017-10-01 at 14:46 +0200, Thorsten Leemhuis wrote:
> Hi, the regression tracker here. What's the status of this issue? Was
> the problem fixed? It seems nothing happened for more than 10 days -- or
> did the discussion move somewhere else? Ciao, Thorsten

The commit was reverted last week before rc2

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=0551968add53777fddd18f4ffb4e3bbc1f646d79

Thanks for tracking it
-Yanko

>
> On 20.09.2017 02:30, Chuck Ebbert wrote:
> > On Tue, 19 Sep 2017 16:51:06 +0100
> > Marc Zyngier <marc.zyngier@arm.com> wrote:
> >
> > > On 19/09/17 16:40, Yanko Kaneti wrote:
> > > > On Tue, 2017-09-19 at 16:33 +0100, Marc Zyngier wrote:
> > > > > On 19/09/17 16:12, Yanko Kaneti wrote:
> > > > > > Hello,
> > > > > >
> > > > > > Fedora rawhide config here.
> > > > > > AMD FX-8370E
> > > > > >
> > > > > > Bisected a problem to:
> > > > > > 74def747bcd0 (genirq: Restrict effective affinity to interrupts
> > > > > > actually using it)
> > > > > >
> > > > > > It seems to be causing stalls, short lived or long lived lockups
> > > > > > very shortly after boot. Everything becomes jerky.
> > > > > >
> > > > > > The only visible in the log indication is something like :
> > > > > > ....
> > > > > > [ 59.802129] clocksource: timekeeping watchdog on CPU3: Marking
> > > > > > clocksource 'tsc' as unstable because the skew is too large:
> > > > > > [ 59.802134] clocksource: 'hpet' wd_now:
> > > > > > 3326e7aa wd_last: 329956f8 mask: ffffffff [ 59.802137]
> > > > > > clocksource: 'tsc' cs_now: 423662bc6f
> > > > > > cs_last: 41dfc91650 mask: ffffffffffffffff [ 59.802140] tsc:
> > > > > > Marking TSC unstable due to clocksource watchdog [ 59.802158]
> > > > > > TSC found unstable after boot, most likely due to broken BIOS.
> > > > > > Use 'tsc=unstable'. [ 59.802161] sched_clock: Marking unstable
> > > > > > (59802142067, 15510)<-(59920871789, -118714277) [ 60.015604]
> > > > > > clocksource: Switched to clocksource hpet [ 89.015994] INFO:
> > > > > > NMI handler (perf_event_nmi_handler) took too long to run:
> > > > > > 209.660 msecs [ 89.016003] perf: interrupt took too long
> > > > > > (1638003 > 2500), lowering kernel.perf_event_max_sample_rate to
> > > > > > 1000 ....
> > > > > >
> > > > > > Just reverting that commit on top of linus mainline cures all the
> > > > > > symptoms
> > > > >
> > > > > Interesting. Do you still get HPET interrupts?
> > > >
> > > > Sorry, I might need some basic help here (i.e where do I count
> > > > them...)
> > >
> > > /proc/interrupts should display them.
> > >
> > > > After the watchdog switches the clocksource to hpet the system is
> > > > still somewhat alive, so I'll guess some clock is still
> > > > ticking....
> > >
> > > Probably, but I suspect they're not hitting the right CPU, hence the
> > > lockups.
> > >
> > > Unfortunately, my x86-foo is pretty minimal, and I'm about to drop off
> > > the net for a few days.
> > >
> > > Thomas, any insight?
> >
> > Looking at flat_cpu_mask_to_apicid(), I don't see how 74def747bcd0
> > can be correct:
> >
> > struct cpumask *effmsk =
> > irq_data_get_effective_affinity_mask(irqdata); unsigned long
> > cpu_mask = cpumask_bits(mask)[0] & APIC_ALL_CPUS;
> >
> > if (!cpu_mask)
> > return -EINVAL;
> > *apicid = (unsigned int)cpu_mask;
> > cpumask_bits(effmsk)[0] = cpu_mask;
> >
> > Before that patch, this function wrote to the effective mask
> > unconditionally. After, it only writes to effective_mask if it is
> > already non-zero.
> >
> >
> > http://news.gmane.org/find-root.php?message_id=20170919203044.560cb9f1%40gmail.com
> > http://mid.gmane.org/20170919203044.560cb9f1%40gmail.com
> >

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