[Bug 216859] New: PCI bridge to bus boot hang at enumeration

[Bjorn Helgaas]

[+cc sound folks]

On Wed, Dec 28, 2022 at 06:02:48AM -0600, Bjorn Helgaas wrote:
> On Wed, Dec 28, 2022 at 08:37:52AM +0000, bugzilla-daemon at kernel.org wrote:
> > https://bugzilla.kernel.org/show_bug.cgi?id=216859
> 
> >            Summary: PCI bridge to bus boot hang at enumeration
> >     Kernel Version: 6.1-rc1
> > ...
> 
> > With Kernel 6.1-rc1 the enumeration process stopped working for me,
> > see attachments.
> > 
> > The enumeration works fine with Kernel 6.0 and below.
> > 
> > Same problem still exists with v6.1. and v6.2.-rc1
> 
> Thank you very much for your report, Zeno!
> 
> v6.0 works, v6.1-rc1 fails.  Would you mind booting v6.1-rc1 with the
> "ignore_loglevel initcall_debug" kernel parameters and taking a photo
> when it hangs?
> 
> How did you conclude that the hang is related to a PCI bridge?  I see
> recent PCI messages in the photo, but it looks like the last message
> is from NFS, so I'm wondering if I'm missing some context.  The v6.0
> dmesg shows several other ntfs, fuse, JFS, etc messages before more
> PCI-related things.  Anyway, the "initcall_debug" might help us narrow
> it down a bit.

Thanks very much for the bisection (complete log at [1])!

The bisection claims the first bad commit is:

  833477fce7a1 ("Merge tag 'sound-6.1-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound")

with parents:

  7e6739b9336e ("Merge tag 'drm-next-2022-10-05' of git://anongit.freedesktop.org/drm/drm")
  86a4d29e7554 ("Merge tag 'asoc-v6.1' of https://git.kernel.org/pub/scm/linux/kernel/git/broonie/sound into for-linus")

Both 7e6739b9336e and 86a4d29e7554 tested "good" during the bisection.

There is a minor conflict when merging 86a4d29e7554 into the upstream,
but I can't imagine that being resolved incorrectly.

Would you mind turning off CONFIG_SOUND in your .config and testing
833477fce7a1 again?  I'm a little skeptical that the hang would be
sound-related, but I guess it's a place to start.

Bjorn

[1] https://bugzilla.kernel.org/show_bug.cgi?id=216859#c35