linux-kernel - Re: PROBLEM: 4.15.0-rc3 APIC causes lockups on Core 2 Duo laptop

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Date:   Fri, 29 Dec 2017 06:49:15 -0500
From:   Alexandru Chirvasitu <achirvasub@...il.com>
To:     Thomas Gleixner <tglx@...utronix.de>
Cc:     Dou Liyang <douly.fnst@...fujitsu.com>,
        Pavel Machek <pavel@....cz>,
        kernel list <linux-kernel@...r.kernel.org>,
        Ingo Molnar <mingo@...hat.com>,
        "Maciej W. Rozycki" <macro@...ux-mips.org>,
        Mikael Pettersson <mikpelinux@...il.com>,
        Josh Poulson <jopoulso@...rosoft.com>,
        Mihai Costache <v-micos@...rosoft.com>,
        Stephen Hemminger <sthemmin@...rosoft.com>,
        Marc Zyngier <marc.zyngier@....com>, linux-pci@...r.kernel.org,
        Haiyang Zhang <haiyangz@...rosoft.com>,
        Dexuan Cui <decui@...rosoft.com>,
        Simon Xiao <sixiao@...rosoft.com>,
        Saeed Mahameed <saeedm@...lanox.com>,
        Jork Loeser <Jork.Loeser@...rosoft.com>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        devel@...uxdriverproject.org, KY Srinivasan <kys@...rosoft.com>
Subject: Re: PROBLEM: 4.15.0-rc3 APIC causes lockups on Core 2 Duo laptop

All right, I tried to do some more digging around, in the hope of
getting as close to the source of the problem as I can.

I went back to the very first commit that went astray for me, 2db1f95
(which is the only one actually panicking), and tried to move from its
parent 90ad9e2 (that boots fine) to it gradually, altering the code in
small chunks.

I tried to ignore the stuff that clearly shouldn't make a difference,
such as definitions. So in the end I get defined-but-unused-function
errors in my compilations, but I'm ignoring those for now. Some
results:

(1) When I move from the good commit 90ad9e2 according to the attached
bad-diff (which moves partly towards 2db1f95), I get a panic.

(2) On the other hand, when I further change this last panicking
commit by simply doing


----------------------------------------------------------------
    removed activate / deactivate from x86_vector_domain_ops

diff --git a/arch/x86/kernel/apic/vector.c b/arch/x86/kernel/apic/vector.c
index 7317ba5a..063594d 100644
--- a/arch/x86/kernel/apic/vector.c
+++ b/arch/x86/kernel/apic/vector.c
@@ -514,8 +514,6 @@ void x86_vector_debug_show(struct seq_file *m, struct irq_domain *d,
 static const struct irq_domain_ops x86_vector_domain_ops = {
        .alloc          = x86_vector_alloc_irqs,
        .free           = x86_vector_free_irqs,
-       .activate       = x86_vector_activate,
-       .deactivate     = x86_vector_deactivate,
 #ifdef CONFIG_GENERIC_IRQ_DEBUGFS
        .debug_show     = x86_vector_debug_show,
 #endif
----------------------------------------------------------------

all is well. 




On Fri, Dec 29, 2017 at 09:07:45AM +0100, Thomas Gleixner wrote:
> On Thu, 28 Dec 2017, Alexandru Chirvasitu wrote:
> > On Fri, Dec 29, 2017 at 12:36:37AM +0100, Thomas Gleixner wrote:
> > > On Thu, 28 Dec 2017, Alexandru Chirvasitu wrote:
> > > 
> > > > Attached, but heads up on this: when redirecting the output of lspci
> > > > -vvv to a text file as root I get
> > > > 
> > > > pcilib: sysfs_read_vpd: read failed: Input/output error
> > > > 
> > > > I can find bugs filed for various distros to this same effect, but
> > > > haven't tracked down any explanations.
> > > 
> > > Weird, but the info looks complete.
> > > 
> > > Can you please add 'pci=nomsi' to the 4.15 kernel command line and see
> > > whether that works?
> > 
> > It does (emailing from that successful boot as we speak). I'm on a
> > clean 4.15-rc5 (as in no patches, etc.). 
> > 
> > This was also suggested way at the top of this thread by Dexuan Cui
> > for 4.15-rc3 (where this exchange started), and it worked back then
> > too.
> 
> I missed that part of the conversation. Let me stare into the MSI code
> again.
> 
> Thanks,
> 
> 	tglx

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