Screen corruption of webkit2gtk apps in X11 on Raspberry Pi, such as during install

This bug has been reported on the Ubuntu ISO testing tracker.

A list of all reports related to this bug can be found here:
https://iso.qa.ubuntu.com/qatracker/reports/bugs/2037015

Not occurring on the latest daily on either Pi 4 or 5; I'm guessing the recent updates of mutter or mesa are responsible.

Bah, spoke too early. This is *not* occurring on the Pi 5, but *is* occurring on the Pi 4 (tested both with the final image). Setting to low priority because it's a purely cosmetic issue; the installation prompts still work happily, and so does the installation afterwards.

Confirmed happening on the Pi4 with the latest Mantic RCs.

This occurring on daily ISO 20-11-2023 Ubuntu Noble Pi4

Now affecting the 22.04.4 jammy ISO

Same issue in Yelp (the Help app) when in Xorg sessions. So I think this is a webkit2gtk bug that only manifests on Xorg (like our installer/live sessions).

Also I have removed the series targets because they were getting cluttered and likely targeting the wrong package anyway.

There's an intriguingly different style of corruption in the noble images on the Pi 5. It's still just on the installer's slides, but it's more ... "chunky"? I'll attach a photo...

That's expected; it's just a different graphics memory layout with a different GPU.

Yelp also crashes soon after displaying the corruption: bug 2060938

And webkit2gtk's MiniBrowser has the same crash: bug 2062146

(both in Xorg sessions)

I have a hunch the problems might have started in WebKit 2.43.2 which included a backport of:
https://github.com/WebKit/WebKit/commit/8b0ce3683045d93cd365e91a4299f7e9babfc126

That's forcing us to take a whole new code path which clearly we're just discovering is a bit buggy on some platforms.

To work around it, you can export:

  WEBKIT_DMABUF_RENDERER_FORCE_SHM=1

which should have better performance than another workaround:

  WEBKIT_DISABLE_DMABUF_RENDERER=1

Both of those also solve bug 2060938 and bug 2062146 which I suspect is a newer crash caused by the newer Mesa in Noble. So if people find the installer is reliably crashing recently then that might explain it.

Untested draft fix:
https://salsa.debian.org/webkit-team/webkit/-/merge_requests/19

This is targeted to 24.04 and marked as 'in progress' but is definitely not landing before 24.04 GA on Thursday. What is the overall plan here? should this go to SRU? (It can, but in that case doesn't benefit users wrt the corruption issue in the *installer* until 24.04.1.)

The plan is to SRU since the installer is not the only app affected.

It's non-fatal, 23.10 was released with the same bug. But I expect to have it fixed in time for 24.04.1

Confirmed this fix is now working:
https://salsa.debian.org/webkit-team/webkit/-/merge_requests/20

This is one of those first-touch experience items that, since this is Edubuntu's first foray into the Raspberry Pi experience, I'd rather get right the first time. Unfortunately, the corruption on the slideshow is sub-par and looks amateurish for us. So no, this needs to be reprioritized.

UPDATE: I was fed bad information (or not bad information, but information that was good at the time), and it turns out Edubuntu will have a Raspberry Pi LTS for 24.04, therefore, a 24.04.1.

The crash (bug 2062146) is now awkwardly entangled with this bug. It occurs at the same time as, or usually instead of corruption. Bisected in Mesa:

  https://gitlab.freedesktop.org/mesa/mesa/-/issues/11033#note_2385595

Prior to that regression, I still believe the corruption probably started around:

  https://github.com/WebKit/WebKit/commit/8b0ce3683045d93cd365e91a4299f7e9babfc126

If you need a workaround for both issues then the best I have found is environment:

  WEBKIT_DMABUF_RENDERER_FORCE_SHM=1

I attempted building an Pi desktop installer image with a backport of this patch (from comment 21) in noble (https://launchpad.net/~waveform/+archive/ubuntu/webkit/+packages) and it appears to fix both the slide corruption, and the crash when booting from certain media (LP: #2064208) for me. This should be a candidate for SRU to noble, when possible.

Looks like I need to make a new debdiff on top of 2.44.1-1 for Oracular.

Saw this bug too when installing Ubuntu 24.04 on a Raspberry Pi 5.

Here's a new debdiff for oracular. But it's not feasible for me to retest building it this week.

Here's the debdiff for Noble. Although with limited hardware resources at the moment, I haven't tested it since April.

And of course those have been superseded now.

Here's a refreshed patch for Oracular. Since I keep having to rebase and regenerate these I won't bother with Noble until Oracular actually gets uploaded.

This bug was fixed in the package webkit2gtk - 2.44.2-1ubuntu1

---------------
webkit2gtk (2.44.2-1ubuntu1) oracular; urgency=medium

  * Convert disable-dmabuf-nvidia.patch to disable-dmabuf.patch,
    adding detection for Broadcom to work around corruption and crashes
    occurring in Raspberry Pi X11 sessions. (LP: #2037015, LP: #2062146)
  * debian/control: Change Maintainer to Ubuntu Developers.

 -- Daniel van Vugt <email address hidden> Wed, 29 May 2024 17:44:52 +0800

My understanding is that while this bug manifests as graphical corruption in the common case, when running on a RPi booted from an SSD the memory map is permuted in such a way that it instead results in a crash. Therefore raising the severity of the bug accordingly, in line with duplicate LP: #2064208.

The crash is bug 2062146

Dropped importance again because High is already noted in bug 2062146. Since the crash started some time after this bug, I believe that's probably a separate regression in Mesa. Even though crashing does sound related to corruption.

Here's a fresh patch for Noble updates.

I've uploaded the noble SRU now

Hello Dave, or anyone else affected,

Accepted webkit2gtk into noble-proposed. The package will build now and be available at https://launchpad.net/ubuntu/+source/webkit2gtk/2.44.2-0ubuntu0.24.04.2 in a few hours, and then in the -proposed repository.

Please help us by testing this new package. See https://wiki.ubuntu.com/Testing/EnableProposed for documentation on how to enable and use -proposed. Your feedback will aid us getting this update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug, mentioning the version of the package you tested, what testing has been performed on the package and change the tag from verification-needed-noble to verification-done-noble. If it does not fix the bug for you, please add a comment stating that, and change the tag to verification-failed-noble. In either case, without details of your testing we will not be able to proceed.

Further information regarding the verification process can be found at https://wiki.ubuntu.com/QATeam/PerformingSRUVerification . Thank you in advance for helping!

N.B. The updated package will be released to -updates after the bug(s) fixed by this package have been verified and the package has been in -proposed for a minimum of 7 days.

Verified fixed on a Raspberry Pi 400 using version 2.44.2-0ubuntu0.24.04.2

The verification of the Stable Release Update for webkit2gtk has completed successfully and the package is now being released to -updates. Subsequently, the Ubuntu Stable Release Updates Team is being unsubscribed and will not receive messages about this bug report. In the event that you encounter a regression using the package from -updates please report a new bug using ubuntu-bug and tag the bug report regression-update so we can easily find any regressions.

This bug was fixed in the package webkit2gtk - 2.44.2-0ubuntu0.24.04.2

---------------
webkit2gtk (2.44.2-0ubuntu0.24.04.2) noble; urgency=medium

  * Convert disable-dmabuf-nvidia.patch to disable-dmabuf.patch,
    adding detection for Broadcom to work around corruption and crashes
    occurring in Raspberry Pi X11 sessions. (LP: #2037015, LP: #2062146)

 -- Daniel van Vugt <email address hidden> Tue, 04 Jun 2024 15:34:16 +0800