Update (2026-08-07): Reproduced again with MUTTER_DEBUG=kms,render,backend active, and this time caught something concrete.
The freeze began at 19:11:55.232206 (page-flip sequence 7231973), when a direct-scanout page-flip to the external 4K monitor's CRTC (145) — using an explicit-sync IN_FENCE_FD, most likely fullscreen hardware-decoded video — completed with no error or warning. From that point until the journalctl dump 6.5 minutes later (19:18:24), CRTC 145 received zero further primary-plane commits, page-flip requests, or damage-clip updates — not even a failed attempt is logged. The only recurring activity for that CRTC is KMS: Realizing HW cursor for cursor sprite for CRTC 145, repeated 471 times with no accompanying plane commit — mutter keeps re-positioning the hardware cursor sprite but never resubmits a frame. Meanwhile the internal laptop panel's CRTC (88) kept flipping normally for the entire window, confirming this stall is isolated to one output's frame clock rather . No drmModeAtomicCommit errors, nokernel/DRM messages around this timestamp either — this output's render/frame-clock path simply goes silent after a successful direct-scanout commit. This differs from the three short "Invalid aay before (2026-08-06, 20:14/20:44/22:17) —those recovered on their own within ~1 second and look like a separate, harmless glitch. This capture points more specifically at: the frame clock for an outpepaint after a direct- scanout page-flipcompletes (possibly a lost/never-fired completion event for the next frame, or the client never being asked to produce another buffer). Attaching a trimmed excerpt (journal_excerpt minutes covering the run-up and the fullstall). The complete boot log (all ~32h, ~980MB, same MUTTER_DEBUG settings) is available at https://bruijn.nu/journal.txt for anyone who wants full context. ** Attachment added: "journal_excerpt_19-05_tot_freeze.txt.gz" https://bugs.launchpad.net/ubuntu/+source/mutter/+bug/2162087/+attachment/5990402/+files/journal_excerpt_19-05_tot_freeze.txt.gz -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/2162087 Title: External monitor freezes completely (incl. cursor) on Meteor Lake iGPU, audio continues To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/mutter/+bug/2162087/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
