Bug 18466

Summary: Alternating between VTs with GDM & GNOME mixes up the displays of the two X servers on NVidia
Product: Mageia Reporter: Theodoros Kalamatianos <thkala>
Component: RPM PackagesAssignee: GNOME maintainers <gnome>
Status: NEW --- QA Contact:
Severity: major    
Priority: Normal CC: marja11, olav, tmb
Version: Cauldron   
Target Milestone: ---   
Hardware: x86_64   
OS: Linux   
Whiteboard:
Source RPM: CVE:
Status comment:

Description Theodoros Kalamatianos 2016-05-16 03:05:58 CEST 
Description of problem:

Currently GDM and the logged-on GNOME session exist on different X servers. If I use Alt+Fn to alternate between the two a few times, I end up with parts of the "other" desktop being in the background of each X server. This kind of issue:

1. Is visually extremely annoying, esp. in the GDM session where there is no way to reload it easily.

2. Can leave parts of one's desktop exposed unintentionally, even when locked.

3. Is indicative of device memory management issues in the kernel driver - maybe more. The two X servers should be completely isolated from each other, but they are obviously not. I would not be surprised if someone could write an exploit out of this.

I would consider this issue serious enough to warrant downgrading whatever component is causing this to a previous version, hence the "Major" severity.

Version-Release number of selected component (if applicable):

nvidia-current-361.42-10.mga6.nonfree.src.rpm

How reproducible:

Always

Steps to Reproduce:
1. Select GDM as the display manager
2. Logon to GNOME
3. Use Alt_Fn to flip back and forth between the GDM and GNOME sessions a few times.
Marja Van Waes 2016-05-16 09:08:04 CEST

CC: (none) => marja11
Assignee: bugsquad => olav

Comment 1 Theodoros Kalamatianos 2016-05-16 09:50:36 CEST 
This does not seem to happen on my Mageia 5 laptop with:

nvidia-current-kernel-4.1.15-desktop-2.mga5-346.96-5.mga5.nonfree
gnome-shell-3.14.3-8.1.mga5
gdm-3.14.2-5.mga5
x11-server-xorg-1.16.4-2.1.mga5
x11-driver-video-nvidia-current-346.96-1.mga5.nonfree

Since GDM does not run on its own X server in Mageia 5, I logged on to GNOME and then started a second X server via the switch-user functionality. I flipped back and forth between the two X servers several times and nothing seems to be leaking. 

The VT switch itself is not as as seamless on Mga5, as if it's going through text mode first. This could mean that some additional hardware reset is happening on Mga5 that is now optimized out on Mga6.

I'll update the software on the laptop to latest Mageia 5 and have another try.
Rémi Verschelde 2016-05-17 11:37:23 CEST

CC: (none) => tmb

Comment 2 Thomas Backlund 2016-05-17 11:46:51 CEST 
yeah, probably a fallout of upstream nvidia-current driver rework
Comment 3 Theodoros Kalamatianos 2016-05-17 21:02:09 CEST 
For the record, this is still happening with kernel 4.6.0-desktop-1.mga6. Not that I expected it to change (that would have been a nice surprise as everything else is the same!).
Olav Vitters 2016-09-19 09:44:42 CEST

Assignee: olav => gnome

Comment 4 Olav Vitters 2016-09-19 09:51:52 CEST 
Nvidia also requires a 'refresh the nvidia background' command when coming from suspend. Maybe similar is needed to switch across VTs. We're moving to GNOME 3.22, let's see what works there.

CC: (none) => olav