1853974 - Large rendering artifacts on text pages

Status: UNCONFIRMED

(Core :: Graphics: WebRender, defect)

Description

[Nazar Mokrynskyi]

Attachment: IMG_20230919_202123_920.jpg

On some text pages without images and such I get large rendering artifacts.
This happens both in Firefox and in Thunderbird with plain text images and was happening for months, I just to to finally report it now.
It seems to depend on Firefox window size since resizing removes these artifacts.

Right now happening on https://bcachefs.org/ErasureCoding/ with Firefox window size 4608x2592 and Xft.dpi set to 120 (I'm using X11 with 7680x4320 screen and Qtile window manager).

GPU is AMD 5500 XT, right now using kernel 6.5.2 and Mesa 23.3 from git (using oibaf ppa) on Ubuntu 22.04.

Firefox and Thunderbird are the only two applications where I see these kinds of rendering issues.

Making a screenshot with gnome-screenshot doesn't capture artifact, it disappears when screen capture happens, so I made a photo of the screen with my phone instead. Artifacts always look like that: grey rectangles with come colors on the edges.

I know description is very generic, but I'm happy to provide clarifying information.

Comment 1

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

The Bugbug bot thinks this bug should belong to the 'Core::Widget: Gtk' component, and is moving the bug to that component. Please correct in case you think the bot is wrong.

Comment 2

[Martin Stránský [:stransky] (ni? me)]

Looks like gfx issue. Can you please attach content of about:support page?
Thanks.

Comment 3

[Nazar Mokrynskyi]

Attachment: about-support.txt

Here is a bit redacted raw data

Comment 4

[Bob Hood [:bhood]]

Thank you for the about:support. Would it be possible for you to set the gfx.webrender.software pref in about:config to true, and try those same pages to see if the behavior remains after restarting Firefox?

Comment 5

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

The component has been changed since the backlog priority was decided, so we're resetting it.
For more information, please visit BugBot documentation.

Comment 6

[Nazar Mokrynskyi]

Just tried, got identically-looking artifacts at exactly the same location.

Also when I move the cursor under affected area of the screen grey rectangles remain what they are, but colorful pixels between them change without any pattern, all rows between blocks change at once.

Comment 7

[Bob Hood [:bhood]]

Pinging Glenn for a look-see.

Comment 8

[Glenn Watson [:gw]]

Just to clarify - did you restart the browser after changing the gfx.webrender.software preference (about:support should then report Software Webrender is active)?

That disables almost all hardware acceleration, so it's very interesting if the bug still occurs when running SWGL.

Comment 9

[Nazar Mokrynskyi]

I definitely did restart the browser and it does say "WebRender (Software)", yet the issue is still present exactly the same way.

Comment 10

[Glenn Watson [:gw]]

OK, thanks for checking. I have similar AMD hardware on Linux, but don't have display hardware that can repro this.

Would you be able to enable gfx.webrender.debug.picture-caching, and take a picture with that enabled and the artifact (I'm mostly interested to see if the artifact aligns with the debug tile boundaries at all).

In that picture, would you say that the edge of the artifact is right in the middle (horizontal) of the display? Is that always the case, when you resize the window etc?

Would it be possible to do some local testing on your end to see if it still occurs with a different WM and/or running under Wayland?

Comment 11

[Nazar Mokrynskyi]

It stops happening when I enable that option, but it doesn't align with them anyway.

Interestingly, it happens with some zoom levels, but not others.
Out of all available it happens with zoom 70%, 90% and 100%.
No artifacts with others between 30% and 500%.

I have a custom DE, so swapping to wayland is certainly not an option, changing WM is tricky too.
Just tried disabling compton compositor, didn't impact this issue.

Just did whole screen recording with SimpleScreenRecorder and while artifacts were visible, they are not on recording somehow.