On Mon, Jan 29, 2018 at 07:09:22PM +0200, Ville Syrjälä wrote: > On Wed, Dec 13, 2017 at 03:06:55PM +0100, Thomas Gleixner wrote: > > On Wed, 13 Dec 2017, Takashi Iwai wrote: > > > On Wed, 13 Dec 2017 12:35:54 +0100, > > > Thomas Gleixner wrote: > > > > > > > > > > On Mon, 11 Dec 2017, Anand, Jerome wrote: > > > > > > > > On Fri, 8 Dec 2017, Ville Syrjälä wrote: > > > > > > > > > > > > > > > > > On Fri, Dec 08, 2017 at 05:33:23PM +0800, Augustine.Chen wrote: > > > > > > > > > > The chip data of HDMI LPE audio is set to drm_i915_private which > > > > > > > > > > is not consistent with the expectation by x86 APIC driver. > > > > > > > > > > > > > > > > > > Hmm. Why is the apic code looking at data for an irq chip it > > > > > > > > > hasn't created? > > > > > > > > > > > > > > > > > > > > > > > apic code expects an irq domain to be place as generic approach. > > > > > > > > > > > > APIC code does not even see that interrupt at all. It's completely disconnected. > > > > > > > > > > > > > > > > That's the problem - APIC just converts the chip data to its internal > > > > > format and fails. > > > > > > > > How does APIC code end up to touch that interrupt at all? Call stack please. > > > > > > It's found in the bugzilla referred in the patch: > > > https://bugs.freedesktop.org/show_bug.cgi?id=103731 > > > > > > [ 87.353072] irq 298 idata->chip->name hdmi_lpe_audio_irqchip > > > [ 87.353072] irq 298 apic_chip_data > > > [ 87.353073] irq 298 data->domain is NULL > > > [ 87.353120] BUG: unable to handle kernel NULL pointer dereference at (null) > > > [ 87.353132] IP: setup_vector_irq+0x1ba/0x230 > > > [ 87.353133] PGD 0 > > > > > > If my understanding is correct, it happens only with 4.14 and earlier > > > kernels where __setup_vector_irq() loops over the all irqs: > > > > > > static void __setup_vector_irq(int cpu) > > > { > > > struct apic_chip_data *data; > > > struct irq_desc *desc; > > > int irq, vector; > > > > > > /* Mark the inuse vectors */ > > > for_each_irq_desc(irq, desc) { > > > struct irq_data *idata = irq_desc_get_irq_data(desc); > > > > > > data = apic_chip_data(idata); > > > if (!data || !cpumask_test_cpu(cpu, data->domain)) > > > continue; > > > .... > > > > > > And since we have assigned a non-APIC chip data in the driver, the > > > code above refers to a wrong object, leading to Oops. > > > > Bah crap. This information should have been provided earlier instead of > > handwavy 'doesnt work with CONFIG_FOO and hotplug'. > > > > > As a further note, the setup_vector_irq() code has been changed in > > > 4.15, and such a reference won't happen any longer. So the patch > > > isn't necessary for now, although it's not bad to take as a cleanup. > > > And we can eventually put Cc to stable there since it actually works > > > around the issue above for the older kernels -- of course, with more > > > detailed descriptions about the background. > > > > No, that's just tinkering. The proper fix is to make that code robust. > > > > Something like the completely untested patch below should do the trick. > > > > Thanks, > > > > tglx > > --- > > diff --git a/arch/x86/kernel/apic/vector.c b/arch/x86/kernel/apic/vector.c > > index f3557a1eb562..02e6a3cc0d74 100644 > > --- a/arch/x86/kernel/apic/vector.c > > +++ b/arch/x86/kernel/apic/vector.c > > @@ -58,6 +58,9 @@ static struct apic_chip_data *apic_chip_data(struct irq_data *irq_data) > > while (irq_data->parent_data) > > irq_data = irq_data->parent_data; > > > > + if (irq_data->domain != x86_vector_domain) > > + return NULL; > > + > > return irq_data->chip_data; > > } > > > > > > Did this patch resolve the issue? Ping. -- Ville Syrjälä Intel OTC _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
