black screen when switching between multiple X session

[zvaral]

[Workaround]
For some people removing the gnome-screensaver package resolves the problem.

[Report]
Binary package hint: fast-user-switch-applet

Switching user from a gnome-session results in a dark screen (similar to a virtual terminal) having only one message on it:

init: unreadahead-other main process (731) terminated with status 4

The following log files are added to the compressed archive:
/var/log/gdm/:0.log
/var/log/gdm/:0.log.1
/var/log/gdm/:0-greeter.log
/var/log/gdm/:0-greeter.log.1
/var/log/syslog
/var/log/Xorg.0.log

uname -a
Linux homepc 2.6.32-14-generic #20-Ubuntu SMP Sat Feb 20 05:18:19 UTC 2010 x86_64 GNU/Linux
---
Architecture: amd64
DistroRelease: Ubuntu 10.04
InstallationMedia: Ubuntu 10.04 "Lucid Lynx" - Alpha amd64 (20100224.1)
Package: gdm 2.30.0-0ubuntu3
PackageArchitecture: amd64
ProcEnviron:
 PATH=(custom, user)
 LANG=en_US.UTF-8
 SHELL=/bin/bash
ProcVersionSignature: Ubuntu 2.6.32-19.28-generic 2.6.32.10+drm33.1
Tags: lucid
Uname: Linux 2.6.32-19-generic x86_64
UserGroups: adm admin cdrom dialout lpadmin plugdev sambashare

[zvaral (z-varallyay)]

This issue is solved with the latest updates.

[Peter B P (peterbp)]

Lucid Beta 1, just installed yesterday on top of a Karmic 9.10.

I get a crash/quit on boot as well, for the followings applets:

The panel encountered a problem while loading "OAFIID:GNOME_FastUserSwitchApplet".
The panel encountered a problem while loading "OAFIID:GNOME_IndicatorApplet".

(the FUSA's functionality can be worked-around by pressing ctrl-alt-del, which bring up the reboot menu.)

[Ivanka Majic (ivanka)]

I don't get an error message but I do get a black screen when switching users in Lucid. Using today's daily build.

[Ted Gould (ted)]

I'm putting this in GDM so it goes on the right path. Indicator session just asks GDM to switch to the user. So it seems this is likely to be a GDM bug.

[Cédric Dufour (cdufour-keyword-ubuntu-086000)]

Could it be upstart related? I experience the same bug and temporarily solved it by restarting GDM after a 15 seconds delay in /etc/rc.local.

[Rick Spencer (rick-rickspencer3)]

Martin, could you please take a look? I'm thinking of you because it is user switching related. Please change assignment as appropriate.

[zvaral (z-varallyay)]

apport information

[zvaral (z-varallyay)]

Unfortunately, this issue is still exist. I recollected some information logging in remotely to the computer which leaved a black screen (without any additional text). Previous attachments relate to this action.

What happened: I switched user successfully used the computer and logged out after. At this stage, I obtained a black screen without any possibility to return to the previous user.

[Martin Pitt (pitti)]

Thanks for the gdm logs. It seems gdm has some difficulties with ConsoleKit, but I'm afraid I need more details, at least the ck-list-sessions and ps aux output.

If other people want to provide information, here are instructions how to collect everything interesting:

 * Open a Terminal and do

      echo 'rm -r /var/log/gdm/* /var/log/Xorg*' | sudo -s

 * reboot
 * log in as one user
 * attempt to switch user

You should now be on a black screen, as reported. Press Control-Alt+F1, log into the text console, and do

  ps aux > /tmp/ps.txt
  who > /tmp/who.txt
  ck-list-sessions > /tmp/ck.txt 2>&1
  sudo tar czvf ~/logs.tar.gz /var/log/gdm /var/log/Xorg* /var/log/kern.log /tmp/ps.txt /tmp/who.txt /tmp/ck.txt

The press Control-Alt-F7 or Control-Alt-F8 to get back to your original session (if neither works, just restart the computer with Control-Alt-Delete), and attach logs.tar.gz here.

Thanks!

[mr.goose (editor-garfnet)]

Sadly, when I swap user and the screen goes blank, I cannot get a text console using Control-Alt+F1 either.

Best wishes, G.

[zvaral (z-varallyay)]

The information could be collected using remote login to the crashed machine.

The requested logs and other outputs are attached in the tar gzipped file.

I must note that I do not experience this bug when I switch the user and switch back in every case but when firefox is running this bug is usually occurring.

The crashed computer could be repaired easily by killing gdm remotely.

[Martin Pitt (pitti)]

The logs look all good, I can't see an obvious error there. (There's unfortunately some noise, since the old gdm and X logs weren't cleaned up before). The first X.org continues to run, but the second starts up and shuts down again. Unfortunately there's no error message anywhere.

zvaral, after you try to switch users, you said that you land in a virtual terminal with text output. Are you able to switch back to your original GNOME session with Ctrl+Alt+F7 or Ctrl+Alt+F8? If so, does it work if you do Ctrl+Alt+F1, log in as that other user you were trying to switch to ("gabi"?) and run "startx"?

[zvaral (z-varallyay)]

The problem step by step:

1. After booting up I can login and start up some applications (firefox, xterm, etc.)
2. I Change the user by clicking the switch off button (up-right corner on the upper panel) and select an other name
3. I find my self on a gdm login window where the selected user's password has to be typed
4. After typing the password gnome-session starts and I can use this user's desktop.
5. After launching some applications (firefox, image viewer, etc.) I choose log out from this user which should result in a return of the previous user (or to the locked screen) but a blank screen appears. With the latest updates I do not get any text massage or similar just a black screen with the pointer I can move around but I can not do anything.
6. Trying to switch to a virtual console (Ctrl+Alt+F1, F2, etc.) the pointer disappear but the screen is still black without any possibility to type login information. (Of course, I can type the authentication blindly and run for example, sudo reboot, which will reboot the machine showing it works properly but the screen is not OK.) Switching back to X (Alt+F7) the small arrow shape of the pointer can be seen again and able to move it but the screen is still totally black.
7. This is the reason I connected the machine remotely. Network connection works but the screen can not be seen. When I logged in from an other computer and killed gdm it restarted properly and the gdm login screen appeared again.

I try to test this issue further and find relating information or any error and I will report them later.

[Martin Pitt (pitti)]

Thanks. This sounds like an issue between the video driver and DRM to me.

[Wolfgang Kufner (wolfgangkufner)]

I have the almost exact same symptoms (I never see a pointer) on intel graphics:

00:02.0 VGA compatible controller [0300]: Intel Corporation Mobile 4 Series Chipset Integrated Graphics Controller [8086:2a42] (rev 07)

[Bryce Harrington (bryce)]

Btw, do not attach files in tarballs. This prevents our scripts from being able to process your bug report and thus prevents the issue from appearing on the developer priority lists.

[Aethralis (aethralis)]

I'm experiencing nearly the same behaviour with Intel Corporation 4 Series Chipset Integrated Graphics Controller (rev 03) as zvaral above - except I have no pointer visible anywhere.

[Leo Milano (lmilano)]

Same behavior here, ATI open source driver, current Lucid, but this is with KDM and Kubuntu. I'll probably try with a more current mainline kernel.

[Aethralis (aethralis)]

I can confirm from the bug #549632 if you do alt+f2 and type: xgamma -gamma 1.0 that restores the display.

[David Clayton (dcstar)]

I am using 64-bit Lucid and have this issue with my ATI hardware (using the fglrx driver).

[Kernel-1 (oligofrenolog)]

Same behaviour on Lenovo S10e, (Intel GMA950). Blank, black screen.

[Angelo Lisco (angystardust-gmail)]

Same here with an Intel card. I think the importance of this bug should be marked as HIGH

[Luca Borrione (luca.borrione)]

Hello guys!

Same problem here with a fresh installation of Lucid Lynx 10.04 final release:
Motherboard -> Intel D850GB (Garibaldi)
cpu -> Intel Pentium 4 - 2.0 GHz
graphic card -> ATI Radeon 9250 128 MB DDR

problem:
1. logged in as admin user
2. try to switch to any user (admin or not with encrypted home or not) by pressing "switch user" under the menu of the right icon of the top panel next to the logged user-name
3. get a blank screen with no pointer. alt+f7 no effect, ctrl+alt+f7 no effect, ctrl+alt+f1/f2 etc sometimes got a console mode sometimes not.

*******************************************************************

I found a work-around (don't know if this is the right place to post it):
case A: you don't care about desktop effects
1. turn-off your desktop effects
2. reboot
3. it might be solved
4. if not type on a terminal:
$ sudo chmod +w /boot/grub/grub.cfg
$ gksudo gedit /boot/grub/grub.cfg
find a line in your desired menuentry like:
linux /boot/vmlinuz-2.6.32-21-generic root=UUID=95595d29-44d9-4b57-9b02-cbb5c5f127aa ro quiet splash
and add nomodeset at the end to obtain something like
linux /boot/vmlinuz-2.6.32-21-generic root=UUID=95595d29-44d9-4b57-9b02-cbb5c5f127aa ro quiet splash nomodeset
$ sudo chmod -w /boot/grub/grub.cfg
5. reboot
6. it might be solved
7. if not I don't know :)

case B: you do care about desktop effects
This is more complex:
1. from a terminal install ati-drivers
$ sudo apt-get install xorg-driver-fglrx
2. reboot
3. completely remove using synaptic any package with fglrx.
In my case:
fglrx
fglrx-kernel-source
xorg-driver-fglrx
fglrx-amdcccle
fglrx-modaliases
(I know that I've installed xorg-driver-fglrx just now but I need some dependencies it install with the above command but I cnnot understand which ones .. so I first install it with all the dependencies and then I remove it .. ok?)
4. reinstall:
libgl1-mesa-glx
libgl1-mesa-dri
xserver-xorg-video-ati
5. reboot
6. it might be solved
7. if not (as in my case) type in a terminal:
$ gksudo /etc/X11/xorg.conf
and write inside the (blank) document:
Section "Device"
        Identifier "Configured Video Device"
        Driver "ati"
        BusID "PCI:1:0:0"
        Option "XAANoOffscreenPixmaps"
        Option "AGPMode" "8"
        Option "AccelMethod" "EXA"
        Option "ColorTiling" "on"
EndSection
save and close.
8. turn-on your desktop effects and try to switch user and it might be ok.

Sometimes when closing the session I get a prompt asking me to enter the password rather then getting the gdm gui .. on this prompt I cannot click on the bottom buttons (something as "change user" "leave a message" and so on ) but I can still reach them by using the alt button.

Hoping that can help!

I sent an old post here
http://ubuntuforums.org/showthread.php?t=1368746

[Luca Borrione (luca.borrione)]

just adding that in case B sometimes the blank screen got back when cosing the switched user session.
I solved it:
1. changing the above conf codes in xorg.conf from Option "AGPMode" "8" to Option "AGPMode" 1"
2. completely removing the gnome-screensaver package as suggested here
https://bugs.launchpad.net/ubuntu/+source/xorg-server/+bug/546578

I don't know if these info are useful for debugging action. Hope so. cheers

[Luca Borrione (luca.borrione)]

sorry .. the problem still remains .. so forget my previous posts :(
It seems a problem of memory: if I switch without any app opened everything go right, but if just open some firefox wins and a openoffice document and then try to switch get the blank screen ..

I tried to use the User Switcher panel applet, instead of the Indicator Applet Session as suggested here
https://bugs.launchpad.net/ubuntu/+source/xorg-server/+bug/546578
and that seems to work with all desktop effects turned off.

However even in this case if I close all the user sessions through the User Switcher panel applet the gdm panel is no more shown and can only press ctrl+f1 login and write sudo /etc/init.d/gdm restart to get it.

[jeffbl (jeff-mulb)]

Similar issue on Ubuntu Lucid 64-bit, upgraded from karmic on a Thinkpad x200. Switching users typically works a few times, then I get the black screen. Occasionally there is a mouse pointer, but usually not. I can't switch to a virtual terminal, and have to ctrl-alt-backspace, which typically brings up the list of users, with the user I was trying to switch to no longer logged in.

[Pants (pants-poopalo)]

Same issue here 10.04 and Mobility Radeon HD 4650

[Mikael Moring (micke-iki)]

Similar issue after upgrading from karmic to lucid on a Dell Latitude D610 (ati mobility radeon x300)

switch user:
- sometimes works (but not too often)
- sometimes gives a blank screen with live mousepointer, but not able to do anything
- sometimes gives garbled screen
- sometimes I can "escape back" with ctrl-alt-f7
- sometimes ctrl-alt-f7 + ctrl-alt-bkspc (which I have enabled) helps
- sometimes I am not able to get back at all (hard power down required)

similar behavior if trying to do switch user when waking up from sleep.
similar behavior if changing gdm to kdm or gnome to kde

[AttilaN (attila123456)]

Seems to work with 2.6.33 and 34-rc6 kernels.

[Frank (flamontagne)]

Having this problem as well on Ubuntu 10.04 and Mobility Radeon 4100

I can switch the first time from user A to user B... then if I switch back to user A I get a black screen with a mouse pointer but cannot do anything.

[David Clayton (dcstar)]

And has been posted previously in the other similar bug reports, remove the gnome-screensaver package and all of the sudden these things start to work as they are supposed to.

[Frank (flamontagne)]

David, I tried removing the gnome-screensaver package but that didn't solve the user switching bug.

[toogreen (toogreen-hotmail)]

Hmm, strange that it didn't fix the problem for Frank, because I also tried removing the gnome-screensaver package, and indeed it solved the problem completely!! I can now even switch back and forth with both users running Compiz and all the eye candy.

Now are there any alternative screensavers to gnome-screensaver, and shouldn't this bug rather be linked to gnome-screensaver as well?

[David Clayton (dcstar)]

I installed the xscreensaver package as I only blank my screen after a certain period and don't need fancy (and wasteful) "eye candy" when I don't use the machine.

This seems to be one of those bugs where two different functions "assume" that they system will be in a particular state when it looks like that in reality it isn't, and the finger must be pointed at both packages that need some basic code cleaning to fix things.

[CarbonPepper (carbonpepper)]

I also get this problem. ATI HD 4670on 64 bit. User switching results in blank screen, and Ctrl+Alt+f1 / f2 etc doesn;t work. Neither does Alt+ SysRq+(anything). Machine is completely dead needing a power off.

This also happens when switching display - Ctrl+Alt+f1 is OK, but switching back to to GUI with Ctrl+Alt+f7 results in the same locked-up machine.

[zvaral (z-varallyay)]

I think bug #546578 is a duplicate of this one reported almost a month later than this bug report. Of course, finally, it has no sense, but some logic order should be kept in reporting bugs.

[Wolfgang Kufner (wolfgangkufner)]

Hi zvaral

First of all thank you for reporting this bug.

I saw that the two reports were about the same bug and made the decision to mark them duplicates this way around for purely practical reasons:
afaik a bug which has duplicates can not be made a duplicate itself without unduping all those duplicates. bug 546578 already had 4 duplicates.
bug 546578 had the upstream link (and as far as I can see those bug header entries are not inherited from duplicates)
bug 546578 already had a header entry for xorg-server which has been suggested as the culprit in the upstream comments (the bug shows on both ati and intel)
it also had an even higher affects count
it had the workaround in the bug description before bug 529882
So all in all this seemed to be the better (more convenient, more useful) way to mark them duplicates.

Best regards
Wolfgang Kufner

[emigrant (fromwindowstolinux)]

I removed the gnome-screen saver and i continued to have the problem. then reinstalled the package after adding the proposed repos to the apt list. now still i have this problem.. :(

[troythetechguy (troythetechguy)]

I was having a similar problem, except my screen would display all sorts of colors mashed together. I disabled visual effects by changing the setting from normal to none in the appearance menu and this appears to have resolved the issue.

[penalvch (penalvch)]

zvaral, this bug was reported a while ago and there hasn't been any activity in it recently. We were wondering if this is still an issue? If so, could you please test for this with the latest development release of Ubuntu? ISO images are available from http://cdimage.ubuntu.com/daily-live/current/ .

If it remains an issue, could you please run the following command in the development release from a Terminal (Applications->Accessories->Terminal), as it will automatically gather and attach updated debug information to this report:

apport-collect 529882

[Launchpad Janitor (janitor)]

[Expired for xorg (Ubuntu) because there has been no activity for 60 days.]