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

 

** Description changed:

  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)
+ 6. Notice screen corruption. Notice that you cannot get to a terminal with Ctrl Alt F1 and that the capslock key doesn't blink the capslock indicator. No mouse pointer is visible. 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. In gdb, Type continue and the computer logs in.(EDIT:couldn't get the continue trick to work every time. Killing at gdbs and then all Xorgs with signal 9 may get you unstuck.)  (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. (EDIT, I did this process again and it happened at an earlier step-- I may have found a separate bug).
  
  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

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