[nvidia] Gnome Shell freeze (page allocation failure in nvidia_modeset)

Sounds like a fairly common problem according to [this page](https://wiki.ubuntu.com/X/Troubleshooting/Freeze): my display freezes, and while I'm still able to move the mouse around, I can't successfully click or type at any windows. It takes about 30 seconds for gnome-shell to restart, and then the clock starts running (and the system monitor starts updating) again.

This problem has been bugging me for a few months now, but I'm not sure when it started. It tends to happen in clumps; sometimes it will go several days without happening, but once it starts it often happens twice pretty quickly, and often a few times across a day. I haven't been able to isolate what causes it, but more often than not it has something to do with clicking on a window or tab in Chrome. (It definitely also happens in other applications, though.)

Every time it happens, dmesg contains a stack dump for gnome-shell ("page allocation failure"). I can provide gists of these dumps if that's helpful (and not already included in the apport data). So I'm not sure if this is actually an xorg thing or a gnome-shell thing.

% lsb_release -rd
Description: Ubuntu 20.10
Release: 20.10

% dpkg -l xorg* gnome-shell* | grep '^ii'
ii gnome-shell 3.38.1-1ubuntu1.1 amd64 graphical shell for the GNOME desktop
ii gnome-shell-common 3.38.1-1ubuntu1.1 all common files for the GNOME graphical shell
ii gnome-shell-extension-appindicator 34-1 all AppIndicator/KStatusNotifierItem support for GNOME Shell
ii gnome-shell-extension-desktop-icons 20.04.0+git20200908-1 all desktop icon support for GNOME Shell
ii gnome-shell-extension-prefs 3.38.1-1ubuntu1.1 amd64 tool to enable / disable GNOME Shell extensions
ii gnome-shell-extension-system-monitor 38+git20200414-32cc79e-1 all Display system information in GNOME Shell status bar
ii gnome-shell-extension-system76-power 2.0.0~1602857239~20.10~914b531~dev all Gnome-shell extension for System76 Power Management
ii gnome-shell-extension-ubuntu-dock 68ubuntu20.10.1 all Ubuntu Dock for GNOME Shell
ii gnome-shell-extensions 3.38.1-1 all Extensions to extend functionality of GNOME Shell
ii xorg 1:7.7+19ubuntu15 amd64 X.Org X Window System
ii xorg-docs-core 1:1.7.1-1.1 all Core documentation for the X.org X Window System
ii xorg-sgml-doctools 1:1.11-1 all Common tools for building X.Org SGML documentation

ProblemType: Bug
DistroRelease: Ubuntu 20.10
Package: xorg 1:7.7+19ubuntu15
ProcVersionSignature: Ubuntu 5.8.0-7630.32~1605108806~20.10~7e52b13~dev-generic 5.8.17
Uname: Linux 5.8.0-7630-generic x86_64
NonfreeKernelModules: nvidia_modeset nvidia
.proc.driver.nvidia.capabilities.gpu0: Error: [Errno 21] Is a directory: '/proc/driver/nvidia/capabilities/gpu0'
.proc.driver.nvidia.capabilities.mig: Error: [Errno 21] Is a directory: '/proc/driver/nvidia/capabilities/mig'
.proc.driver.nvidia.gpus.0000.01.00.0: Error: [Errno 21] Is a directory: '/proc/driver/nvidia/gpus/0000:01:00.0'
.proc.driver.nvidia.registry: Binary: ""
.proc.driver.nvidia.suspend: suspend hibernate resume
.proc.driver.nvidia.suspend_depth: default modeset uvm
.proc.driver.nvidia.version:
 NVRM version: NVIDIA UNIX x86_64 Kernel Module 455.38 Thu Oct 22 06:06:59 UTC 2020
 GCC version: gcc version 10.2.0 (Ubuntu 10.2.0-13ubuntu1)
ApportVersion: 2.20.11-0ubuntu50.1
Architecture: amd64
BootLog:

CasperMD5CheckResult: skip
CompizPlugins: No value set for `/apps/compiz-1/general/screen0/options/active_plugins'
CompositorRunning: None
CurrentDesktop: ubuntu:GNOME
Date: Thu Nov 19 15:05:17 2020
DistUpgraded: 2020-11-16 10:15:57,099 DEBUG Running PostInstallScript: './xorg_fix_proprietary.py'
DistroCodename: groovy
DistroVariant: ubuntu
ExtraDebuggingInterest: Yes, if not too technical
GraphicsCard:
 NVIDIA Corporation GP106 [GeForce GTX 1060 3GB] [10de:1c02] (rev a1) (prog-if 00 [VGA controller])
   Subsystem: eVga.com. Corp. GP106 [GeForce GTX 1060 3GB] [3842:6162]
InstallationDate: Installed on 2018-01-19 (1035 days ago)
InstallationMedia: Ubuntu 17.10 "Artful Aardvark" - Release amd64 (20180105.1)
MachineType: System76, Inc. Wild Dog Performance
ProcEnviron:
 TERM=xterm-256color
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=en_US.UTF-8
 SHELL=/bin/bash
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-5.8.0-7630-generic root=UUID=e12a4ebc-6235-4471-a2da-3f9da9d48f74 ro quiet splash vt.handoff=7
SourcePackage: xorg
Symptom: display
Title: Xorg freeze
UpgradeStatus: Upgraded to groovy on 2020-11-16 (3 days ago)
dmi.bios.date: 03/05/2013
dmi.bios.release: 4.6
dmi.bios.vendor: Intel Corp.
dmi.bios.version: KCH7710H.86A.0108.2013.0305.1638
dmi.board.name: DH77KC
dmi.board.vendor: Intel Corporation
dmi.board.version: AAG39641-400
dmi.chassis.type: 3
dmi.chassis.vendor: System76, Inc.
dmi.chassis.version: wilp9
dmi.modalias: dmi:bvnIntelCorp.:bvrKCH7710H.86A.0108.2013.0305.1638:bd03/05/2013:br4.6:svnSystem76,Inc.:pnWildDogPerformance:pvrwilp9:rvnIntelCorporation:rnDH77KC:rvrAAG39641-400:cvnSystem76,Inc.:ct3:cvrwilp9:
dmi.product.family: To be filled by O.E.M.
dmi.product.name: Wild Dog Performance
dmi.product.sku: To be filled by O.E.M.
dmi.product.version: wilp9
dmi.sys.vendor: System76, Inc.
version.compiz: compiz N/A
version.libdrm2: libdrm2 2.4.102-1ubuntu1
version.libgl1-mesa-dri: libgl1-mesa-dri 20.2.1-1
version.libgl1-mesa-glx: libgl1-mesa-glx 20.2.1-1
version.nvidia-graphics-drivers: nvidia-graphics-drivers-* N/A
version.xserver-xorg-core: xserver-xorg-core 2:1.20.9-2ubuntu1
version.xserver-xorg-input-evdev: xserver-xorg-input-evdev N/A
version.xserver-xorg-video-ati: xserver-xorg-video-ati 1:19.1.0-1ubuntu1
version.xserver-xorg-video-intel: xserver-xorg-video-intel 2:2.99.917+git20200714-1
version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau 1:1.0.16-1