1708498 - Browser windows stop updating after toggling KWin compositing

Status: RESOLVED INCOMPLETE

(Core :: Graphics: WebRender, defect)

Description

[zorael]

User Agent: Mozilla/5.0 (X11; Linux x86_64; rv:88.0) Gecko/20100101 Firefox/88.0

Steps to reproduce:

Manjaro/Arch x86_64, Firefox 88 from Manjaro repositories but also affects nightly as of 210429. Tested with a fresh ~/.mozilla, tested with and without MOZ_X11_EGL=1. Compositing is WebRender. Dell XPS 13 so Intel graphics, mesa 21.0.3. Kernel is 5.12.

When a resolution change is induced in a particular way (here by the game manager Lutris), all open Firefox windows stop updating their contents. They can still be interacted with; keyboard shortcuts work, mouseover tooltips pop up, you can open the menu etc, but the contents freeze as they were at time of the change in resolution. Changing the resolution via the desktop environment's display manager or via xrandr does not trigger this behaviour. From what I could tell no other programs other than Firefox seem to be affected.

Notably, if I at this point open a new Firefox window with Ctrl+N, or via Firefox's menu button, the newly spawned window opens normally and can be interacted with without issues. It is as such possible to keep using Firefox after the resolution switch, but only by opening more windows. Mind that these in turn also become defunct when the game closes and the resolution is once again changed, back to the original state. Closing Firefox entirely and relying on it to restore the previous session seems to be the only way to recover.

(This is going to be very specific and annoying to reproduce (installation of Lutris and a game), but hopefully the behaviour makes sense to someone. Likely several games exhibit this behaviour; I only have this one concrete example as of now.)

1. Install Lutris, https://lutris.net/downloads or from distro repositories where available
2. Download (for instance) the Guild Wars 2 launcher with it (by clicking the DXVK variant installer link at https://lutris.net/games/guild-wars-2). You don't need to install the whole game, just the launcher (and maybe some runtimes)
3. Right-click game entry in Lutris, Configure, System options
4. Change "Switch resolution to" setting to something other than "Keep current (default)" to make it change resolution on game launch
5. Save configuration and and start game

Actual results:

Resolution changes, game starts and Firefox stops updating its windows' contents. It cannot be interacted with except by spawning new windows. Nothing of particular interest is output to the terminal.

Expected results:

Resolution changes, game starts and Firefox keeps on working as it did prior to game launch.

Comment 1

[BugBot [:suhaib / :marco/ :calixte]]

The Bugbug bot thinks this bug should belong to the 'Core::DOM: Core & HTML' component, and is moving the bug to that component. Please revert this change in case you think the bot is wrong.

Comment 2

[zorael]

Further testing shows that what's causing it is toggling KWin compositing (on or off). Wine, Lutris etc are not needed, and the title should probably be changed. (I don't know how.)

Steps to reproduce:

1. Run KDE, kwin ~5.21.4
2. Start Firefox 88
3. Toggle compositing with Alt+Shift+F12

Actual results:
As described above; windows stop updating their contents, but new ones can be created to continue browsing. A full program restart is needed to recover.

Expected results:
Firefox continues to work even when toggling compositing on or off.

Comment 3

[zorael]

To update, the workaround I've found is to disable WebRender (with MOZ_WEBRENDER=0) and fall back to the OpenGL compositor (with layers.acceleration.force-enabled). That, or live with kwin compositing persistently off.

I did test with the current nightly downloaded from the official website, and the behaviour is still prevalent as of today, 210513.

(The title should arguably be changed to "Browser windows stop updating after toggling KWin compositing".)

Comment 4

[Robert Mader [:rmader]]

This sounds similar to bug 1712665, however only EGL should be effected then. There can still rendering issues, but they should go away when e.g. scrolling IIRC. Zorael, can you retest if this still happens on nightly?

Comment 5

[BugBot [:suhaib / :marco/ :calixte]]

Clear a needinfo that is pending on an inactive user.

Inactive users most likely will not respond; if the missing information is essential and cannot be collected another way, the bug maybe should be closed as INCOMPLETE.

For more information, please visit auto_nag documentation.

Comment 6

[zorael]

For what it's worth at this point it seems to work now.