Re: IRQ behaivour has been changed from v4.14 to v4.15-rc1

[Thomas Gleixner]

On Thu, 28 Dec 2017, Andy Shevchenko wrote:
> On Thu, 2017-12-28 at 18:44 +0100, Thomas Gleixner wrote:
> > On Thu, 28 Dec 2017, Andy Shevchenko wrote:
> > > On Thu, 2017-12-28 at 18:21 +0100, Thomas Gleixner wrote:
> > > > > [   85.167061] spurious APIC interrupt through vector ff on
> > > > > CPU#0,
> > > > > should never happen.
> > > > > [   85.199886] atomisp-isp2 0000:00:03.0: stream[0] started.
> > > > > 
> > > > > and Ctrl+C does NOT work. Machine just hangs.
> > > > > 
> > > > > It might be related to this:
> > > > > https://lkml.org/lkml/2017/12/22/697
> > > > 
> > > > I don't think so.
> > > > 
> > > > Does the patch below cure it?
> > > 
> > > Unfortunately, no.
> > > 
> > > Same behaviour.
> > > 
> > > Tell me if I need to provide some debug before it hangs. For now I
> > > have
> > > apic=debug (AFAIR it doesn't affect this).
> > 
> > The interesting question is why that spurious APIC interrupt through
> > vector
> > ff happens. Can you please add the following to the kernel command
> > line:
> > 
> >  'trace_events=irq_vectors:* ftrace_dump_on_oops'
> > 
> > and apply the patch below. That should spill out the trace over serial
> > (I
> > hope you have that ...)
> 
> With or without CONFIG_FUNCTION_TRACER=y I have got
> 
> 
> [   28.977918] Dumping ftrace buffer:
> [   28.988115]    (ftrace buffer empty)
> 
> followed by BUG() output.
> 
> ...
> [   28.930154] RIP: 0010:smp_spurious_interrupt+0x67/0xb0
> ...
> 
> 
> Anything I missed?

Yes, you missed the typo in the command line. It should be:

 'trace_event=irq_vectors:* ftrace_dump_on_oops'

Thanks,

	tglx