Suspend takes 3 minutes and screen is garbled after resume with nouveau driver after upgrade to 19.10

[DRracer]

In Kubuntu 19.04 (kernel 5.0) suspend and resume was almost working on my machine, say 9 of 10 times it went well. The problematic suspends were mostly when there way an OpenGL app running. I was able to lived with that, the machine was able to achieve 30+days uptime.

After upgrading to 19.10 the machine now behaves weird:
1. Suspend takes 3 minutes to complete. The screen blanks relatively fast as before, but the machine is up and running for another 3 minutes before finally entering sleep.

2. Resume is normal as before and does its job, however:
- the screen is completely garbled. It looks like the video RAM content was lost.
- the GPU seems to operate normally, the cursor is drawn correctly (see attached photo).

3. Restarting the X-server resolves the issue, i.e. the screen contains reasonable content

4. Text console is working correctly even without restarting the X-server

5. Tried running KDE with and without compositor, got the same results.

I'd like to help fixing this or at least provide technical info that will lead to fixing this issue, please tell me what shall I try/test. Thank you.

ProblemType: Bug
DistroRelease: Ubuntu 19.10
Package: xserver-xorg-video-nouveau 1:1.0.16-1
ProcVersionSignature: Ubuntu 5.3.0-18.19-generic 5.3.1
Uname: Linux 5.3.0-18-generic x86_64
ApportVersion: 2.20.11-0ubuntu8
Architecture: amd64
BootLog: Error: [Errno 13] Permission denied: '/var/log/boot.log'
CompositorRunning: None
CurrentDesktop: KDE
Date: Sun Oct 20 23:18:53 2019
DistUpgraded: 2019-10-19 10:33:23,032 DEBUG Running PostInstallScript: './xorg_fix_proprietary.py'
DistroCodename: eoan
DistroVariant: ubuntu
DkmsStatus: virtualbox, 6.0.14, 5.3.0-18-generic, x86_64: installed
ExtraDebuggingInterest: No
GraphicsCard:
 NVIDIA Corporation G94M [GeForce 9800M GS] [10de:062b] (rev a1) (prog-if 00 [VGA controller])
   Subsystem: Micro-Star International Co., Ltd. [MSI] G94M [GeForce 9800M GS] [1462:7220]
InstallationDate: Installed on 2019-04-21 (182 days ago)
InstallationMedia: Kubuntu 19.04 "Disco Dingo" - Release amd64 (20190416)
MachineType: Micro-Star International GT627
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-5.3.0-18-generic root=UUID=bec74662-d895-4581-a6ea-6f92fea32635 ro resume=/dev/sda6 iommu=soft
SourcePackage: xserver-xorg-video-nouveau
UpgradeStatus: Upgraded to eoan on 2019-10-19 (1 days ago)
dmi.bios.date: 04/07/2009
dmi.bios.vendor: American Megatrends Inc.
dmi.bios.version: A1651IMS.10V
dmi.board.asset.tag: To Be Filled By O.E.M.
dmi.board.name: MS-1651
dmi.board.vendor: MSI
dmi.board.version: Ver 1.000
dmi.chassis.asset.tag: To Be Filled By O.E.M.
dmi.chassis.type: 3
dmi.chassis.vendor: To Be Filled By O.E.M.
dmi.chassis.version: To Be Filled By O.E.M.
dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvrA1651IMS.10V:bd04/07/2009:svnMicro-StarInternational:pnGT627:pvrVer1.000:rvnMSI:rnMS-1651:rvrVer1.000:cvnToBeFilledByO.E.M.:ct3:cvrToBeFilledByO.E.M.:
dmi.product.family: To Be Filled By O.E.M.
dmi.product.name: GT627
dmi.product.sku: To Be Filled By O.E.M.
dmi.product.version: Ver 1.000
dmi.sys.vendor: Micro-Star International
version.compiz: compiz N/A
version.libdrm2: libdrm2 2.4.99-1ubuntu1
version.libgl1-mesa-dri: libgl1-mesa-dri 19.2.1-1ubuntu1
version.libgl1-mesa-glx: libgl1-mesa-glx N/A
version.xserver-xorg-core: xserver-xorg-core 2:1.20.5+git20191008-0ubuntu1
version.xserver-xorg-input-evdev: xserver-xorg-input-evdev N/A
version.xserver-xorg-video-ati: xserver-xorg-video-ati 1:19.0.1-1ubuntu1
version.xserver-xorg-video-intel: xserver-xorg-video-intel 2:2.99.917+git20190815-1
version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau 1:1.0.16-1

[DRracer (drracer)]

Tried kernel 5.4-rc4
A very similar behavior, suspend takes 3 minutes to complete
After resume, the screen shows the KDE lock screen, but the mouse cursor is just a white box (I assume its bitmap was lost).
The display is unresponsive, however the machine lives, I was able to ssh into it from another machine.
There are nouveau driver crashes in dmesg, see attachment.

I'll try kernel 5.0 if I can make it compile from within Kubuntu 19.10 to see if the suspend/resume problem changes.

[DRracer (drracer)]

kernel 4.19.80
suspend perfect (takes no more than 10s), resume perfect, no graphical glitches.
I belive the nouveau problems are caused by the recent GPU shared memory changes (just skimmed through the latest changes)

[DRracer (drracer)]

kernel 5.2.21 behaves still ok like 4.19.80 and 5.0.x, which has been in Kubuntu 19.04