Getting the regression

Getting the regression

[Thorsten Leemhuis]

Hi Greg! As you likely heard already, 5.19.9 introduced a regression
that breaks Thunderbolt and USB-C docks (and apparently Wifi in some
cases as well) on quite a few (many?) modern systems. It's one of those
problems where I think "hey, we ideally should fix this in stable as
fast as possible" we briefly talked about last week on the LPC hallways.
That made me wonder how to actually archive that in this particular case
while keeping all involved parties happy and not skipping any CI testing
queues considered important.

FWIW, here are a few few reports about the issue (I assume there are
some for Arch Linux and openSUSE Tumbleweed as well, but didn't check).

https://lore.kernel.org/linux-iommu/485A6EA5-6D58-42EA-B298-8571E97422DE@getmailspring.com/
https://bugzilla.kernel.org/show_bug.cgi?id=216497
https://bugzilla.redhat.com/show_bug.cgi?id=2128458
https://bugzilla.redhat.com/show_bug.cgi?id=2127753

A revert of the culprit (9cd4f1434479f ("iommu/vt-d: Fix possible
recursive locking in intel_iommu_init()"); in 5.19.y it's 	9516acba29e3)
for mainline is here:
https://lore.kernel.org/lkml/20220920081701.3453504-1-baolu.lu@linux.intel.com/

A few hours ago the revert was queued to get send to Joerg:
https://lore.kernel.org/linux-iommu/20220921024054.3570256-1-baolu.lu@linux.intel.com/

I fear it could easily take another week to get this fixed in stable
depending on how fast the patch makes it to mainline and the timing of
the next 5.19.y release and its -rc phase. That to me sounds like way
too long for a problem like this that apparently plagues quite a few
people.

That made me wonder: would you in cases like this be willing to start
the -rc phase for a interim 5.19.y release with just that revert while
it's still heading towards mainline? Then the CI systems that test
stable -rcs could chew on things already; and the new stable release
could go out right after the revert landed in mainline (unless the
testing finds any problems, of course).

Ciao, Thorsten

How to quickly resolve the IOMMU regression that currently plagues a lot of people in 5.19.y

[Thorsten Leemhuis]

[resend with proper subject, sorry for the noise]

[note to self: don't get distracted when writing the subject]

On 21.09.22 08:53, Thorsten Leemhuis wrote:
> Hi Greg! As you likely heard already, 5.19.9 introduced a regression
> that breaks Thunderbolt and USB-C docks (and apparently Wifi in some
> cases as well) on quite a few (many?) modern systems. It's one of those
> problems where I think "hey, we ideally should fix this in stable as
> fast as possible" we briefly talked about last week on the LPC hallways.
> That made me wonder how to actually archive that in this particular case
> while keeping all involved parties happy and not skipping any CI testing
> queues considered important.
> 
> FWIW, here are a few few reports about the issue (I assume there are
> some for Arch Linux and openSUSE Tumbleweed as well, but didn't check).
> 
> https://lore.kernel.org/linux-iommu/485A6EA5-6D58-42EA-B298-8571E97422DE@getmailspring.com/
> https://bugzilla.kernel.org/show_bug.cgi?id=216497
> https://bugzilla.redhat.com/show_bug.cgi?id=2128458
> https://bugzilla.redhat.com/show_bug.cgi?id=2127753
> 
> A revert of the culprit (9cd4f1434479f ("iommu/vt-d: Fix possible
> recursive locking in intel_iommu_init()"); in 5.19.y it's 	9516acba29e3)
> for mainline is here:
> https://lore.kernel.org/lkml/20220920081701.3453504-1-baolu.lu@linux.intel.com/
> 
> A few hours ago the revert was queued to get send to Joerg:
> https://lore.kernel.org/linux-iommu/20220921024054.3570256-1-baolu.lu@linux.intel.com/
> 
> I fear it could easily take another week to get this fixed in stable
> depending on how fast the patch makes it to mainline and the timing of
> the next 5.19.y release and its -rc phase. That to me sounds like way
> too long for a problem like this that apparently plagues quite a few
> people.
> 
> That made me wonder: would you in cases like this be willing to start
> the -rc phase for a interim 5.19.y release with just that revert while
> it's still heading towards mainline? Then the CI systems that test
> stable -rcs could chew on things already; and the new stable release
> could go out right after the revert landed in mainline (unless the
> testing finds any problems, of course).
> 
> Ciao, Thorsten
> 
> 

Re: How to quickly resolve the IOMMU regression that currently plagues a lot of people in 5.19.y

[Joerg Roedel]

Hi Thorsten,

On Wed, Sep 21, 2022 at 09:15:17AM +0200, Thorsten Leemhuis wrote:
> [resend with proper subject, sorry for the noise]

Thanks for the noise :) I will queue the fix today and send it upstream.

Regards,

	Joerg

Re: How to quickly resolve the IOMMU regression that currently plagues a lot of people in 5.19.y

[Greg KH]

On Wed, Sep 21, 2022 at 10:19:10AM +0200, Joerg Roedel wrote:
> Hi Thorsten,
> 
> On Wed, Sep 21, 2022 at 09:15:17AM +0200, Thorsten Leemhuis wrote:
> > [resend with proper subject, sorry for the noise]
> 
> Thanks for the noise :) I will queue the fix today and send it upstream.

Great, thanks for doing this.

greg k-h

Re: How to quickly resolve the IOMMU regression that currently plagues a lot of people in 5.19.y

[Linus Torvalds]

On Wed, Sep 21, 2022 at 1:19 AM Joerg Roedel <joro@8bytes.org> wrote:
>
> Thanks for the noise :) I will queue the fix today and send it upstream.

.. and it's in my tree now.

                  Linus

Re: How to quickly resolve the IOMMU regression that currently plagues a lot of people in 5.19.y

[Greg KH]

On Wed, Sep 21, 2022 at 09:15:12AM -0700, Linus Torvalds wrote:
> On Wed, Sep 21, 2022 at 1:19 AM Joerg Roedel <joro@8bytes.org> wrote:
> >
> > Thanks for the noise :) I will queue the fix today and send it upstream.
> 
> .. and it's in my tree now.

And now added to the next 5.19-rc release that is out for review now.

thanks for the quick response everyone,

greg k-h