Closed Bug 1703141 Opened 6 months ago Closed 6 months ago

frozen browser (100% cpu) on transition with a hover


(Core :: Graphics: WebRender, defect)

Firefox 89



89 Branch
Tracking Status
firefox-esr78 --- disabled
firefox87 --- wontfix
firefox88 --- verified
firefox89 --- verified


(Reporter: karlcow, Assigned: nical)




(Keywords: regression)


(2 files)

This is a serious bug.

  1. Go to
  2. Hover

Look at the animation

Animation starts then freezes the full browser with a maxed out CPU.

You need to force restart the browser to be able to use it.

Running mozregression gives this range

tested on macos

Though it's strange because Bug 1516056 is just a comment change.
Or did I miss something in the regression range or the crash is random?

The other changeset in the range might be a problem?, this has mac specific changes.

Could someone run a regression window on Windows just to see if it's macos only?

No longer regressed by: 1516056
Component: Panning and Zooming → Graphics: WebRender
Flags: needinfo?(nical.bugzilla)
Blocks: gfx-triage
Assignee: nobody → nical.bugzilla
Flags: needinfo?(nical.bugzilla)
Pushed by
WIP: Bug 1703141 - Prevent infinite loop in gradient fast-path. r=gfx-reviewers,lsalzman
Closed: 6 months ago
Resolution: --- → FIXED
Target Milestone: --- → 89 Branch

Please nominate this for Beta approval.

Flags: needinfo?(nical.bugzilla)

Comment on attachment 9214024 [details]
WIP: Bug 1703141 - Prevent infinite loop in gradient fast-path.

Beta/Release Uplift Approval Request

  • User impact if declined: infinite loop causing freezes
  • Is this code covered by automated tests?: No
  • Has the fix been verified in Nightly?: Yes
  • Needs manual test from QE?: No
  • If yes, steps to reproduce:
  • List of other uplifts needed: None
  • Risk to taking this patch: Low
  • Why is the change risky/not risky? (and alternatives if risky): Simple fix.
  • String changes made/needed: None.
Flags: needinfo?(nical.bugzilla)
Attachment #9214024 - Flags: approval-mozilla-beta?

Comment on attachment 9214024 [details]
WIP: Bug 1703141 - Prevent infinite loop in gradient fast-path.

Approved for 88.0b9, thanks. Can we land a crashtest for this?

Flags: needinfo?(nical.bugzilla)
Attachment #9214024 - Flags: approval-mozilla-beta? → approval-mozilla-beta+
QA Whiteboard: [qa-triaged]
Flags: qe-verify+
Flags: needinfo?(nical.bugzilla)

I was able to reproduce the issue on Firefox 89.0a1 (2021-04-05) under macOS 11.2.3 by using the links from Comment 0.

The issue is fixed on Firefox 88.0b9 and Firefox Nightly 89.0a1 (2021-04-11). Tests were performed on macOS 11.2.3, Windows 10 and Ubuntu 20.04.

Flags: qe-verify+
No longer blocks: gfx-triage
Pushed by
Add a crash test. r=gfx-reviewers,lsalzman
Flags: in-testsuite+
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