xorg segfaults with multiseat configuration

[Fabian Köster]

I am trying to enable a multiseat-configuration with Precise but Xorg segfaults, probably because of some of the input-device declarations. This configuration works with Ubuntu Oneiric so it is probably a regression.

If I do not use a xorg.conf the xserver starts fine (of course without multiseat setup then).

Backtrace:
[ 12.270] 0: /usr/bin/X (xorg_backtrace+0x26) [0x7f5585dd21b6]
[ 12.270] 1: /usr/bin/X (0x7f5585c4a000+0x18c05a) [0x7f5585dd605a]
[ 12.270] 2: /lib/x86_64-linux-gnu/libpthread.so.0 (0x7f5584f70000+0xfcb0) [0x7f5584f7fcb0]
[ 12.270] 3: /lib/x86_64-linux-gnu/libc.so.6 (0x7f5583de6000+0x14ca49) [0x7f5583f32a49]
[ 12.270] 4: /usr/bin/X (NewInputDeviceRequest+0x52) [0x7f5585ce9792]
[ 12.270] 5: /usr/bin/X (InitInput+0x76) [0x7f5585cd7126]
[ 12.270] 6: /usr/bin/X (0x7f5585c4a000+0x3d5d6) [0x7f5585c875d6]
[ 12.270] 7: /lib/x86_64-linux-gnu/libc.so.6 (__libc_start_main+0xed) [0x7f5583e0776d]
[ 12.270] 8: /usr/bin/X (0x7f5585c4a000+0x3d90d) [0x7f5585c8790d]
[ 12.270] Segmentation fault at address (nil)
[ 12.270]
Caught signal 11 (Segmentation fault). Server aborting

ProblemType: Bug
DistroRelease: Ubuntu 12.04
Package: xserver-xorg 1:7.6+10ubuntu1
ProcVersionSignature: Ubuntu 3.2.0-17.26-generic 3.2.6
Uname: Linux 3.2.0-17-generic x86_64
ApportVersion: 1.91-0ubuntu1
Architecture: amd64
CompizPlugins: [core,bailer,detection,composite,opengl,compiztoolbox,decor,mousepoll,vpswitch,move,regex,gnomecompat,wall,grid,imgpng,resize,animation,place,snap,fade,workarounds,session,expo,scale,ezoom,unityshell]
Date: Mon Feb 20 12:07:47 2012
DistUpgraded: Fresh install
DistroCodename: precise
DistroVariant: ubuntu
ExtraDebuggingInterest: Yes, whatever it takes to get this fixed in Ubuntu
GraphicsCard:
 Intel Corporation 4 Series Chipset Integrated Graphics Controller [8086:2e12] (rev 03) (prog-if 00 [VGA controller])
   Subsystem: Lenovo Device [17aa:3049]
   Subsystem: Lenovo Device [17aa:3049]
InstallationMedia: Ubuntu 12.04 LTS "Precise Pangolin" - Alpha amd64 (20120201.2)
MachineType: LENOVO 8820ACG
ProcEnviron:
 LANG=de_DE.UTF-8
 SHELL=/bin/bash
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.2.0-17-generic root=UUID=eb6e6093-100d-4e86-9547-bf9870a5bde2 ro quiet splash vt.handoff=7
SourcePackage: xorg
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 02/01/2010
dmi.bios.vendor: LENOVO
dmi.bios.version: 5CKT61AUS
dmi.board.name: LENOVO
dmi.board.vendor: LENOVO
dmi.board.version: NONE
dmi.chassis.asset.tag: �������������������������
dmi.chassis.type: 3
dmi.chassis.vendor: LENOVO
dmi.chassis.version: NONE
dmi.modalias: dmi:bvnLENOVO:bvr5CKT61AUS:bd02/01/2010:svnLENOVO:pn8820ACG:pvrThinkCentreM58:rvnLENOVO:rnLENOVO:rvrNONE:cvnLENOVO:ct3:cvrNONE:
dmi.product.name: 8820ACG
dmi.product.version: ThinkCentre M58
dmi.sys.vendor: LENOVO
version.compiz: compiz 1:0.9.7.0~bzr2995-0ubuntu4
version.ia32-libs: ia32-libs N/A
version.libdrm2: libdrm2 2.4.30-1ubuntu1
version.libgl1-mesa-dri: libgl1-mesa-dri 8.0~rc2-0ubuntu5
version.libgl1-mesa-dri-experimental: libgl1-mesa-dri-experimental N/A
version.libgl1-mesa-glx: libgl1-mesa-glx 8.0~rc2-0ubuntu5
version.xserver-xorg-core: xserver-xorg-core 2:1.11.4-0ubuntu3
version.xserver-xorg-input-evdev: xserver-xorg-input-evdev 1:2.6.99.901+git20120126-0ubuntu2
version.xserver-xorg-video-ati: xserver-xorg-video-ati 1:6.14.99~git20111219.aacbd629-0ubuntu2
version.xserver-xorg-video-intel: xserver-xorg-video-intel 2:2.17.0-1ubuntu4
version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau 1:0.0.16+git20111201+b5534a1-1build2

[Fabian Köster (maestro-alubia)]

I would like to generate a backtrace for this and according to https://wiki.ubuntu.com/X/Backtracing there should be a file /etc/X11/core but there isn't. How to do it then?

[Bryce Harrington (bryce)]

Yes, it does seem to be a crash in the input subsystem.

As to the core file, X isn't set to dump core by default; you'd have to flip that on.

Since you're able to reproduce this crash fairly at-will, I would actually suggest instead of bothering with the core to just run X inside gdb, let it crash, and then grab a full backtrace. Don't forget to install symbol packages (i.e. the various -dbg packages).

[Peter Wu (lekensteyn)]

The root cause is possibly a duplicate of https://bugs.launchpad.net/ubuntu/+source/xorg-server/+bug/931397

[Fabian Köster (maestro-alubia)]

I have currently no pyhisical access to the machine, but I will generate a full backtrace this weekend.

You are probably right that this is a duplicate, we will see then.

[Fabian Köster (maestro-alubia)]

fabian@betty-desktop:~$ sudo gdb /usr/bin/Xorg
GNU gdb (Ubuntu/Linaro 7.4-0ubuntu1) 7.4
Copyright (C) 2012 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law. Type "show copying"
and "show warranty" for details.
This GDB was configured as "x86_64-linux-gnu".
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>...
Reading symbols from /usr/bin/Xorg...Reading symbols from /usr/lib/debug/usr/bin/Xorg...done.
done.
(gdb) run :0 -layout default -auth /var/run/lightdm/root/:0 -nolisten tcp vt7 -sharevts
Starting program: /usr/bin/Xorg :0 -layout default -auth /var/run/lightdm/root/:0 -nolisten tcp vt7 -sharevts
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".

X.Org X Server 1.11.3
Release Date: 2011-12-16
X Protocol Version 11, Revision 0
Build Operating System: Linux 2.6.24-30-server x86_64 Ubuntu
Current Operating System: Linux betty-desktop 3.2.0-17-generic #26-Ubuntu SMP Fri Feb 17 21:35:49 UTC 2012 x86_64
Kernel command line: BOOT_IMAGE=/boot/vmlinuz-3.2.0-17-generic root=UUID=eb6e6093-100d-4e86-9547-bf9870a5bde2 ro quiet splash vt.handoff=7
Build Date: 14 February 2012 12:07:28AM
xorg-server 2:1.11.4-0ubuntu3 (For technical support please see http://www.ubuntu.com/support)
Current version of pixman: 0.24.4
 Before reporting problems, check http://wiki.x.org
 to make sure that you have the latest version.
Markers: (--) probed, (**) from config file, (==) default setting,
 (++) from command line, (!!) notice, (II) informational,
 (WW) warning, (EE) error, (NI) not implemented, (??) unknown.
(==) Log file: "/var/log/Xorg.0.log", Time: Sat Feb 25 21:01:56 2012
(==) Using config file: "/etc/X11/xorg.conf"
(==) Using system config directory "/usr/share/X11/xorg.conf.d"
[tcsetpgrp failed in terminal_inferior: Die Operation ist nicht erlaubt]

Program received signal SIGSEGV, Segmentation fault.
__strcasecmp_l_ssse3 () at ../sysdeps/x86_64/multiarch/../strcmp.S:213
213 ../sysdeps/x86_64/multiarch/../strcmp.S: Datei oder Verzeichnis nicht gefunden.
(gdb) backtrace full
#0 __strcasecmp_l_ssse3 () at ../sysdeps/x86_64/multiarch/../strcmp.S:213
No locals.
#1 0x00005555555f3792 in NewInputDeviceRequest (options=0x55555597ba20, attrs=0x0, pdev=0x7fffffffe588) at ../../../../hw/xfree86/common/xf86Xinput.c:912
        pInfo = 0x5555575ce530
        option = 0x55555597b9e0
        rval = 0
        is_auto = <optimized out>
#2 0x00005555555e1126 in InitInput (argc=<optimized out>, argv=<optimized out>) at ../../../../hw/xfree86/common/xf86Init.c:893
        pInfo = 0x555555974d20
        dev = 0x55555559a5fc
#3 0x00005555555915d6 in main (argc=10, argv=<optimized out>, envp=<optimized out>) at ../../dix/main.c:258
        i = <optimized out>
        alwaysCheckForInput = {0, 1}
(gdb)