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[Bug 500066] [NEW] X display corruption switching users, uses 100% CPU, seg faults

 

Public bug reported:

To reproduce this bug (on Lucid):
1. login to a user. (We'll call it user #1)
2. Go to switch users
3. Login to another user (i.e. user #2)
4. Go to switch users
5. Try to login to user #1
6. Notice screen corruption. Try sshing in and running top. Notice Xorg processes using 99-100 % CPU. (I expected it to switched to the already running session belonging to user #1)
7. If you had gdb attached to the process, it will return to gdb prompt. Type continue and the computer logs in. (if you didn't have gdb attached, then you have to power off the computer, or run sudo init 6 to get back to normal)
8. Continuing on assuming you do have gdb atached, go to switch users again.
9. Attempt to login to user #2.(I expected it to switched to the already running session belonging to user #2)
10. Notice how you get a background like the gdm, but with no dialog (i.e. the thing that lets you choose users and enter passwords).
11. After waiting awhile, gdb says that the program seg faulted. typing continue at the gdb prompt does nothing.

I tried to get a backtrace with gdb. I make a mistake at step 11; I
should have tried to get a backtrace instead of continuing, so I
killall'ed gdb and reattached it, and got another backtrace.

I will include a picture of the screen corruption that happens at step
6, and a picture of step 11.

bjorn@bjorn-laptop:~$ lsb_release -rd
Description:	Ubuntu lucid (development branch)  // daily image for 12-21-09 or so.
Release:	10.04
bjorn@bjorn-laptop:~$ apt-cache policy xserver-xorg-core
xserver-xorg-core:
  Installed: 2:1.7.3.901-1ubuntu3
  Candidate: 2:1.7.3.901-1ubuntu3
  Version table:
 *** 2:1.7.3.901-1ubuntu3 0
        500 http://us.archive.ubuntu.com lucid/main Packages
        100 /var/lib/dpkg/status

ProblemType: Bug
Architecture: amd64
Date: Wed Dec 23 22:46:13 2009
DistroRelease: Ubuntu 10.04
ExecutablePath: /usr/bin/Xorg
InstallationMedia: Ubuntu 10.04 "Lucid Lynx" - Alpha amd64 (20091221)
Lsusb:
 Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
 Bus 002 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
MachineType: Hewlett-Packard Presario F500 (GF606UA#ABA)
Package: xserver-xorg-core 2:1.7.3.901-1ubuntu3
ProcCmdLine: BOOT_IMAGE=/boot/vmlinuz-2.6.32-9-generic root=UUID=792bbc80-e60b-4fc1-b70a-813005201e60 ro quiet splash
ProcEnviron:
 LANG=en_US.UTF-8
 PATH=(custom, no user)
ProcVersionSignature: Ubuntu 2.6.32-9.13-generic
RelatedPackageVersions:
 xserver-xorg 1:7.5~3ubuntu4
 libgl1-mesa-glx 7.6.1~rc3-1ubuntu1
 libdrm2 2.4.14-1ubuntu2
 xserver-xorg-video-intel 2:2.9.1-1ubuntu1
 xserver-xorg-video-ati 1:6.12.99+git20090929.7968e1fb-0ubuntu2
SourcePackage: xorg-server
Tags: lucid
Uname: Linux 2.6.32-9-generic x86_64
XorgConf: Error: [Errno 2] No such file or directory: '/etc/X11/xorg.conf'
dmi.bios.date: 12/05/2007
dmi.bios.vendor: Hewlett-Packard
dmi.bios.version: F.1F
dmi.board.name: 30D3
dmi.board.vendor: Quanta
dmi.board.version: 65.3A
dmi.chassis.type: 10
dmi.chassis.vendor: Quanta
dmi.chassis.version: N/A
dmi.modalias: dmi:bvnHewlett-Packard:bvrF.1F:bd12/05/2007:svnHewlett-Packard:pnPresarioF500(GF606UA#ABA):pvrRev1:rvnQuanta:rn30D3:rvr65.3A:cvnQuanta:ct10:cvrN/A:
dmi.product.name: Presario F500 (GF606UA#ABA)
dmi.product.version: Rev 1
dmi.sys.vendor: Hewlett-Packard
fglrx: Not loaded
glxinfo: Error: [Errno 2] No such file or directory
system:
 distro:             Ubuntu
 architecture:       x86_64kernel:             2.6.32-9-generic
xkbcomp:
 Error: command ['xkbcomp', ':0', '-w0', '-'] failed with exit code 1: Error:            Cannot open display ":0"
                   Exiting

** Affects: xorg-server (Ubuntu)
     Importance: Undecided
         Status: New


** Tags: amd64 apport-bug lucid

-- 
X display corruption switching users, uses 100% CPU, seg faults
https://bugs.launchpad.net/bugs/500066
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