gnome-screensaver and xscreensaver can not be run at the same time

[karatedog]

Binary package hint: xscreensaver

If automatic bug reporting in Xubuntu takes me here, the site shouldn't ask for more info from me.

ProblemType: Crash
DistroRelease: Ubuntu 10.10
Package: xscreensaver-gl 5.11-1ubuntu2
ProcVersionSignature: Ubuntu 2.6.35-20.29-generic 2.6.35.4
Uname: Linux 2.6.35-20-generic i686
Architecture: i386
Date: Tue Sep 14 01:20:20 2010
Disassembly: => 0xbdb3b0: Cannot access memory at address 0xbdb3b0
ExecutablePath: /usr/lib/xscreensaver/glcells
InstallationMedia: Ubuntu 10.10 "Maverick Meerkat" - Beta i386 (20100901.1)
ProcCmdline: glcells -root
ProcEnviron:
 PATH=(custom, no user)
 LANG=en_US.utf8
 SHELL=/bin/bash
SegvAnalysis:
 Segfault happened at: 0xbdb3b0: Cannot access memory at address 0xbdb3b0
 PC (0x00bdb3b0) not located in a known VMA region (needed executable region)!
SegvReason: executing unknown VMA
Signal: 11
SourcePackage: xscreensaver
StacktraceTop:
 __kernel_vsyscall ()
 select () from /lib/libc.so.6
 ?? ()
 ?? ()
 __libc_start_main () from /lib/libc.so.6
Title: glcells crashed with SIGSEGV in __kernel_vsyscall()
UserGroups: adm admin cdrom dialout lpadmin plugdev sambashare
XsessionErrors:
 (polkit-gnome-authentication-agent-1:13441): GLib-CRITICAL **: g_once_init_leave: assertion `initialization_value != 0' failed
 (bluetooth-applet:13457): Gtk-CRITICAL **: IA__gtk_widget_set_sensitive: assertion `GTK_IS_WIDGET (widget)' failed
 (xfce4-mixer-plugin:13509): libxfce4mixer-CRITICAL **: xfce_mixer_get_track: assertion `GST_IS_MIXER (card)' failed

[Apport retracing service (apport)]

StacktraceTop:
 ?? ()
 main (argc=1, argv=0xbf8d94b4) at screenhack.c:490

[Charlie Kravetz (cjkgeek)]

Please tell us what you were doing when the crash occurred. Even with automatic reporting, we can not see what you as a user were doing. Was this waking from suspend or hibernate?

[karatedog (karatedog)]

  Hi!

Only the screen was turned off, and this was happening inside Virtualbox
(Windows 7 Host, Ubuntu Guest).
OS: Ubuntu 10.04

I just moved the mouse inside the VM (should be same as moving the mouse
on a real PC), the screen came back with a login window, and for a few
seconds everything was normal, then I got the error message.
Nothing else broke.

Best regards,
Leslie

On 2010.09.15 16:40, Charlie Kravetz wrote:
> Please tell us what you were doing when the crash occurred. Even with
> automatic reporting, we can not see what you as a user were doing. Was
> this waking from suspend or hibernate?
>
> ** Attachment removed: "CoreDump.gz"
> https://bugs.launchpad.net/ubuntu/+source/xscreensaver/+bug/637676/+attachment/1580530/+files/CoreDump.gz
>
> ** Changed in: xscreensaver (Ubuntu)
> Status: New => Incomplete
>

[karatedog (karatedog)]

  I don't know if it affects the outcome, but I was in the process of
trying out window managers.
First I installed Ubuntu with Gnome, then installed LXDE, then installed
xubuntu-desktop.
I will try to recreate the bug, if possible (I suspect that a simple
Xubuntu install will not reproduce the error).

On 2010.09.15 16:40, Charlie Kravetz wrote:
> Please tell us what you were doing when the crash occurred. Even with
> automatic reporting, we can not see what you as a user were doing. Was
> this waking from suspend or hibernate?
>
> ** Attachment removed: "CoreDump.gz"
> https://bugs.launchpad.net/ubuntu/+source/xscreensaver/+bug/637676/+attachment/1580530/+files/CoreDump.gz
>
> ** Changed in: xscreensaver (Ubuntu)
> Status: New => Incomplete
>

[karatedog (karatedog)]

When I manually started Applications/Settings/Screensaver it warned me that a Gnome screensaver daemon is running (and I had to shut it down to have XScreensaver to work properly).
From then on, none of the screensavers threw exceptions.

[karatedog (karatedog)]

I've done a fresh reinstall of Xubuntu 10.10 (not an Ubuntu + xubuntu-desktop install) and the screensaver is fine.

[Charlie Kravetz (cjkgeek)]

Thanks for letting us know. I will then be able to attempt to reproduce the issue if I install both screensavers, and if that fails, perhaps an install of Ubuntu, then add Xubuntu. I will do that this weekend in both VBox and Hardware.

[Charlie Kravetz (cjkgeek)]

 Thanks for reporting this bug and any supporting documentation. Since this bug has enough information provided for a developer to begin work, I'm going to mark it as confirmed and let them handle it from here.

If both gnome-screensaver and xscreensaver are installed at the same time, they do conflict with each other when one or the other is running. These two screensavers serve the same purpose and should not be able to be installed together.

Thanks for taking the time to make Ubuntu better!

[Tormod Volden (tormodvolden)]

It should be fine to have both installed (for instance if you have both xfce and gnome users). But a session manager should only start one of them. The xscreensaver package does not install a autostart desktop file for this reason. I believe the xfce session manager takes care of starting xscreensaver itself. I don't know if it starts gnome-screensaver also if it is installed.

In what kind of session did this problem happen? Xfce?

[Charlie Kravetz (cjkgeek)]

This was a fresh Ubuntu Installation, so the session was Gnome. I installed Ubuntu Maverick, then installed xscreensaver. Gnome-screensaver is the default in this case, but there are two screensavers in System -> Preferences. When clicking on the second one, the error appears, since gnome-screensaver is started by default.