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

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Message-ID: <20230726100732.1b9ae446@imammedo.users.ipa.redhat.com>
Date:   Wed, 26 Jul 2023 10:07:32 +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 11:59:56 -0400
Woody Suwalski <terraluna977@...il.com> wrote:

> Igor Mammedov wrote:
> > 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.
> >  
> Good news. After removing the botched debug statement which was masking 
> the original issue, the testing went as you have predicted, and on patch 
> 3 system suspends to RAM OK.
Thanks for confirmation,
I'll post cleaned up 3/3 patch today.

> 
> Here are the requested 3 dmesg outputs, #2 is for the bad run.
> 
> I can retest with a final version of the patch once you have it ready...
> 
> Thanks, Woody
>