Intermittent freeze in display output, XPS 9530 with nouveau

[Luke Carrier]

Display output intermittently pauses for approximately a second, causing the system to appear "stuttery". During freezes mouse input doesn't seem to be registered and keyboard input is repeated, as though keys are being held down.

Watching the journal via `journalctl -f`, the following message appears each time the problem occurs:

Mar 31 20:16:18 luke-ultrabook kernel: nouveau 0000:02:00.0: bus: MMIO write of 00000002 FAULT at 4188ac [ IBUS ]
Mar 31 20:16:27 luke-ultrabook kernel: nouveau 0000:02:00.0: bus: MMIO write of 00000002 FAULT at 4188ac [ IBUS ]

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: xorg 1:7.7+19ubuntu5
ProcVersionSignature: Ubuntu 4.15.0-13.14-generic 4.15.10
Uname: Linux 4.15.0-13-generic x86_64
ApportVersion: 2.20.9-0ubuntu2
Architecture: amd64
CompizPlugins: No value set for `/apps/compiz-1/general/screen0/options/active_plugins'
CompositorRunning: None
CurrentDesktop: GNOME
Date: Sat Mar 31 20:11:01 2018
DistUpgraded: 2018-03-31 16:47:43,480 DEBUG Running PostInstallScript: './xorg_fix_proprietary.py'
DistroCodename: bionic
DistroVariant: ubuntu
EcryptfsInUse: Yes
ExtraDebuggingInterest: Yes
GraphicsCard:
 Intel Corporation 4th Gen Core Processor Integrated Graphics Controller [8086:0416] (rev 06) (prog-if 00 [VGA controller])
   Subsystem: Dell 4th Gen Core Processor Integrated Graphics Controller [1028:05fe]
   Subsystem: Dell GK107M [GeForce GT 750M] [1028:05fe]
InstallationDate: Installed on 2018-01-29 (61 days ago)
InstallationMedia: Ubuntu 17.10 "Artful Aardvark" - Release amd64 (20180105.1)
MachineType: Dell Inc. XPS 15 9530
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-4.15.0-13-generic.efi.signed root=UUID=58327001-b3e0-4118-a0e6-03e8221a44f2 ro quiet splash vt.handoff=1
SourcePackage: xorg
Symptom: display
Title: Xorg freeze
UpgradeStatus: Upgraded to bionic on 2018-03-31 (0 days ago)
dmi.bios.date: 07/30/2015
dmi.bios.vendor: Dell Inc.
dmi.bios.version: A09
dmi.board.name: XPS 15 9530
dmi.board.vendor: Dell Inc.
dmi.board.version: A09
dmi.chassis.type: 8
dmi.chassis.vendor: Dell Inc.
dmi.chassis.version: Not Specified
dmi.modalias: dmi:bvnDellInc.:bvrA09:bd07/30/2015:svnDellInc.:pnXPS159530:pvrA09:rvnDellInc.:rnXPS159530:rvrA09:cvnDellInc.:ct8:cvrNotSpecified:
dmi.product.name: XPS 15 9530
dmi.product.version: A09
dmi.sys.vendor: Dell Inc.
version.compiz: compiz N/A
version.libdrm2: libdrm2 2.4.91-2
version.libgl1-mesa-dri: libgl1-mesa-dri 18.0.0~rc5-1ubuntu1
version.libgl1-mesa-glx: libgl1-mesa-glx 18.0.0~rc5-1ubuntu1
version.xserver-xorg-core: xserver-xorg-core 2:1.19.6-1ubuntu3
version.xserver-xorg-input-evdev: xserver-xorg-input-evdev N/A
version.xserver-xorg-video-ati: xserver-xorg-video-ati 1:18.0.1-1
version.xserver-xorg-video-intel: xserver-xorg-video-intel 2:2.99.917+git20171229-1
version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau 1:1.0.15-2

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.