linux-kernel - Re: [RFC 0/3] acpipcihp: fix kernel crash on 2nd resume

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Message-ID: <20230725171958.1eacd24e@imammedo.users.ipa.redhat.com>
Date:   Tue, 25 Jul 2023 17:19:58 +0200
From:   Igor Mammedov <imammedo@...hat.com>
To:     Woody Suwalski <terraluna977@...il.com>
Cc:     linux-kernel@...r.kernel.org, bhelgaas@...gle.com,
        linux-pci@...r.kernel.org, mst@...hat.com
Subject: Re: [RFC 0/3] acpipcihp: fix kernel crash on 2nd resume

On Tue, 25 Jul 2023 09:51:53 -0400
Woody Suwalski <terraluna977@...il.com> wrote:

> Igor Mammedov wrote:
> > Changelog:
> >    * split out debug patch into a separate one with extra printk added
> >    * fixed inverte bus->self check (probably a reason why it didn't work before)
> >
> >
> > 1/3 debug patch
> > 2/3 offending patch
> > 3/3 potential fix
> >    
> > I added more files to trace, add following to kernel CLI
> >     dyndbg="file drivers/pci/access.c +p; file drivers/pci/hotplug/acpiphp_glue.c +p; file drivers/pci/bus.c +p; file drivers/pci/pci.c +p; file drivers/pci/setup-bus.c +p; file drivers/acpi/bus.c +p" ignore_loglevel
> >
> > should be applied on top of
> >     e8afd0d9fccc PCI: pciehp: Cancel bringup sequence if card is not present
> >
> > apply a patch one by one and run testcase + capture dmesg after each patch
> > one shpould endup with 3 dmesg to ananlyse
> >   1st - old behaviour - no crash
> >   2nd - crash
> >   3rd - no crash hopefully
> >
> > Igor Mammedov (3):
> >    acpiphp: extra debug hack
> >    PCI: acpiphp: Reassign resources on bridge if necessary
> >    acpipcihp: use __pci_bus_assign_resources() if bus doesn't have bridge
> >
> >   drivers/pci/hotplug/acpiphp_glue.c | 23 ++++++++++++++++++-----
> >   1 file changed, 18 insertions(+), 5 deletions(-)
> >  
> Actually applying patch1 is already creating the crash (why???),
probably it's due to an extra debug line, I've added.
I dropped suspicions one, can you try again and see if it works.

> hence I 
> have added also dmesg-6.5-0.txt which shows a working condition based on 
> git e8afd0d9fccc level (acpiphp_glue in kernel 6.4)
> 
> Patch3 did not fix the issue, it seems that the culprit is somewhere 
> else triggered by  "benign" patch1 :-(
> 
> Also note about the trigger description in patch3: the dmesg trace on 
> Inspiron laptop is collected after the first wake from suspend to ram. 
> The consecutive  attempt to sleep results in a frozen system.

Thanks for clarification, I'll correct commit message once culprit
is found.

> 
> Thanks, Woody
>