Re: v5.13-rcX regression - NULL pointer dereference - MFD and software node API

From: Andy Shevchenko <andy.shevchenko@gmail.com>
To: Dominik Brodowski <linux@dominikbrodowski.net>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
	Lee Jones <lee.jones@linaro.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	"Krogerus, Heikki" <heikki.krogerus@linux.intel.com>
Subject: Re: v5.13-rcX regression - NULL pointer dereference - MFD and software node API
Date: Sun, 20 Jun 2021 21:27:34 +0300	[thread overview]
Message-ID: <CAHp75Ve=j+u-9TF0az3o82wOyzixCezkgOm=yUHh37JS_Awiig@mail.gmail.com> (raw)
In-Reply-To: <CAHp75VdSyM7JdGDhdo5t+FbmouEA7ZSOwGAtSwSRD8vTwTc+LA@mail.gmail.com>

On Sun, Jun 20, 2021 at 7:36 PM Andy Shevchenko
<andy.shevchenko@gmail.com> wrote:
> On Sun, Jun 20, 2021 at 2:50 PM Dominik Brodowski
> <linux@dominikbrodowski.net> wrote:
> > Am Sun, Jun 20, 2021 at 02:19:44PM +0300 schrieb Andy Shevchenko:
> > > On Sun, Jun 20, 2021 at 11:36 AM Dominik Brodowski
> > > <linux@dominikbrodowski.net> wrote:
> > > >
> > > > Over a month ago, Andy Shevchenko reported and fixed a NULL pointer
> > > > dereference issue introduced by commit
> > > >         42e59982917a ("mfd: core: Add support for software nodes")
> > > > in v5.13-rc1:
> > > >         https://lore.kernel.org/lkml/20210510141552.57045-1-andriy.shevchenko@linux.intel.com/
> > > >
> > > > A bisect shows that it is indeed commit 42e59982917a which causes boot to
> > > > fail due to a NULL pointer dereference on my work laptop,
> > >
> > > Can you, please, be more specific? E.g. where may I find the ACPI dump
> > > of your laptop, along with other information?
> > > What you may prepare is (all run under root user)
> > > 1. `acpidump -o laptop-$MODEL.dat` (the *.dat file)
> > > 2. `grep -H 15 /sys/bus/acpi/devices/*/status`
> > > 3. `dmesg`
> > > 4. `cat /proc/iomem /proc/ioport`
> > > 5. `lspci -nk -vv`
> > >
> > > (#2 and #3 are interesting to have in working and non-working cases)
> > >
> > > Perhaps a bug on the kernel bugzilla would be a good container for all these.
> > >
> > > Also it's not clear what exactly an Oops you have (I don't believe
> > > it's the same).
> >
> > Thanks for taking a look at this issue. As it's actually a panic during
> > boot which triggers before initramfs is ready, I can only provide the data
> > for the "working case", i.e. with the patch causing the regression already
> > reverted:
> >
> >         https://bugzilla.kernel.org/show_bug.cgi?id=213511
> >
> > With commit 42e59982917a reverted, the system works just fine.
>
> Is it possible to have any traces of the panic to be logged / photoed / etc?

I'm just wondering (based on the idea behind my fix) if the commenting
out INT3446 ID entry in the intel-lpss-acpi.c will help boot this? If
so, you may try to bind it later to the driver and see the Oops.

-- 
With Best Regards,
Andy Shevchenko