Flickering of the graphical environment (i915 [drm] GPU HANG)

[Martins K.]

Ubuntu 20.10
uname -r: 5.8.0-50-generic
Machine: Lenovo T440s

1) The graphical environment starts flickering, drawing the windows and their content scrambled, flashing, etc. Over the time the graphical environment disintegrates completely (scrambled windows, horizontal lines and solid squares all over the screen, impossible to use any controls or even to understand where they are), rendering any further work impossible (the only remedy is to reboot the system). At the onset of those symptoms dmesg or the like do not contain anything informative; however, usually the graphical environment also at some point freezes for a moment. When this happens, the dmesg gets appended with lines informing about a gpu hang:

[28620.924309] i915 0000:00:02.0: [drm] GPU HANG: ecode 7:1:dfdef4fe, in Renderer [104270]
[28620.924474] i915 0000:00:02.0: [drm] Resetting chip for stopped heartbeat on rcs0
[28621.027257] i915 0000:00:02.0: [drm] Renderer[104270] context reset due to GPU hang
[28654.972181] i915 0000:00:02.0: [drm] GPU HANG: ecode 7:1:00200000, in Renderer [104270]
[28654.973039] i915 0000:00:02.0: [drm] Resetting chip for stopped heartbeat on rcs0
[28655.075025] i915 0000:00:02.0: [drm] Renderer[104270] context reset due to GPU hang

This is the probably the only possibly relevant info I could find in the logs.

2) Reproducing: no specific steps are known. I noticed that using Firefox usually speeds up the onset of the problems, but the bug presents itself also when using other programs (e.g., Wolfram Mathematica).

3) The bug started to manifest itself since updating to the kernel 5.8.0-49 via apt upgrade. Most tellingly, booting with 5.8.0-48 leads to stable, working system without any of the described problems.

4) The only recent relevant report I could find seems to be this one:
https://gitlab.freedesktop.org/drm/intel/-/issues/2986

ProblemType: Bug
DistroRelease: Ubuntu 20.10
Package: linux-image-5.8.0-50-generic 5.8.0-50.56
ProcVersionSignature: Ubuntu 5.8.0-50.56-generic 5.8.18
Uname: Linux 5.8.0-50-generic x86_64
ApportVersion: 2.20.11-0ubuntu50.5
Architecture: amd64
AudioDevicesInUse: Error: command ['fuser', '-v', '/dev/snd/by-path', '/dev/snd/controlC1', '/dev/snd/hwC1D0', '/dev/snd/pcmC1D0c', '/dev/snd/pcmC1D0p', '/dev/snd/controlC0', '/dev/snd/hwC0D0', '/dev/snd/pcmC0D10p', '/dev/snd/pcmC0D9p', '/dev/snd/pcmC0D8p', '/dev/snd/pcmC0D7p', '/dev/snd/pcmC0D3p', '/dev/snd/seq', '/dev/snd/timer'] failed with exit code 1:
CasperMD5CheckResult: skip
Date: Thu Apr 22 09:31:48 2021
InstallationDate: Installed on 2015-03-18 (2226 days ago)
InstallationMedia: Ubuntu 14.10 "Utopic Unicorn" - Release amd64 (20141022.1)
MachineType: LENOVO 20ARS45900
ProcFB: 0 i915drmfb
ProcKernelCmdLine: BOOT_IMAGE=/vmlinuz-5.8.0-50-generic root=/dev/mapper/ubuntu--vg-root ro quiet splash elevator=noop vt.handoff=7
PulseList: Error: command ['pacmd', 'list'] failed with exit code 1: No PulseAudio daemon running, or not running as session daemon.
RelatedPackageVersions:
 linux-restricted-modules-5.8.0-50-generic N/A
 linux-backports-modules-5.8.0-50-generic N/A
 linux-firmware 1.190.3
SourcePackage: linux
UpgradeStatus: Upgraded to groovy on 2020-10-23 (180 days ago)
dmi.bios.date: 01/09/2015
dmi.bios.release: 2.32
dmi.bios.vendor: LENOVO
dmi.bios.version: GJET82WW (2.32 )
dmi.board.asset.tag: Not Available
dmi.board.name: 20ARS45900
dmi.board.vendor: LENOVO
dmi.board.version: SDK0E50512 STD
dmi.chassis.asset.tag: No Asset Information
dmi.chassis.type: 10
dmi.chassis.vendor: LENOVO
dmi.chassis.version: Not Available
dmi.ec.firmware.release: 1.9
dmi.modalias: dmi:bvnLENOVO:bvrGJET82WW(2.32):bd01/09/2015:br2.32:efr1.9:svnLENOVO:pn20ARS45900:pvrThinkPadT440s:rvnLENOVO:rn20ARS45900:rvrSDK0E50512STD:cvnLENOVO:ct10:cvrNotAvailable:
dmi.product.family: ThinkPad T440s
dmi.product.name: 20ARS45900
dmi.product.sku: LENOVO_MT_20AR_BU_Think_FM_ThinkPad T440s
dmi.product.version: ThinkPad T440s
dmi.sys.vendor: LENOVO

[Ubuntu Kernel Bot (ubuntu-kernel-bot)]

This change was made by a bot.

[Martins K. (martinsk89)]

Attaching a screenshot showing some of the early symptoms (see the scrambled content of the terminal, the horizontal line, as well as the oddly colored apport tab in tint2).

Usually the effects are dynamic (e.g., an icon or some part of the window gets drawn, disappears, gets drawn again, ad infinitum), so a screencast probably could be more illustrative (if necessary, I can find out how to record one).