Re: PCI/MSI: kernel NULL pointer dereference

[Bjorn Helgaas <helgaas@kernel.org>]

On Thu, Sep 08, 2022 at 04:30:28PM +0200, Daniel Gomez wrote:
> On Thu, 8 Sept 2022 at 15:44, Deucher, Alexander
> <Alexander.Deucher@amd.com> wrote:
> > > -----Original Message-----
> > > From: Bjorn Helgaas <helgaas@kernel.org>
> > > Sent: Thursday, September 8, 2022 8:13 AM
> > > To: Daniel Gomez <daniel@qtec.com>
> > > Cc: linux-pci@vger.kernel.org; Thomas Gleixner <tglx@linutronix.de>;
> > > Deucher, Alexander <Alexander.Deucher@amd.com>; Koenig, Christian
> > > <Christian.Koenig@amd.com>
> > > Subject: Re: PCI/MSI: kernel NULL pointer dereference
> > >
> > > On Thu, Sep 08, 2022 at 12:41:00PM +0200, Daniel Gomez wrote:
> > > > Hi,
> > > >
> > > > I have the following error whenever I remove the fglrx module from the
> > > > latest 6.0-rc4.
> > >
> > > You bisected to 93296cd1325d; I don't see a commit with a "Fixes:"
> > > that references that.  If you can reproduce this with an in-tree driver, we can
> > > certainly fix it, but it's harder for an out-of-tree driver.
> I understand, thanks. I tried with radeon but rmmod it is not possible
> once it's loaded.

A brute-force way to debug this would be to add logging to entry
points in msi.c so you can see what MSI-related interfaces fglrx uses
and in what order.  Then you may be able to make a trivial module that
does something similar that we could use as a test case so we could
duplicate the failure and verify a fix.

Bjorn