Ubuntu
unity package

[Oneiric] alt+tab makes unity crashed (with gdb logs)

Bug #946965 reported by Tim Chen
158
This bug affects 48 people
Affects Status Importance Assigned to Milestone
OEM Priority Project
Won't Fix
Medium
James M. Leddy
Oneiric
Won't Fix
Undecided
Unassigned
Precise
Invalid
Undecided
Unassigned
Unity
Invalid
High
Unassigned
Unity 4.30.0 "SRU3"
unity (Ubuntu)
Invalid
High
Unassigned
Oneiric
Won't Fix
High
Unassigned

Bug Description

Expected results:
alt+tab hot-key successfully switch the application to foreground for me.

Actual results:
Sometimes it crashed the window system, and most time it works

Reproduce:
1. login
2. open gnome-terminal via unity panel
3. open chromium-browser via unity panel
4. press alt + tab

(sometimes it will crash, if not, re-do it again.)

I attached gdb log in the bug, it seems the error happened at
unity::switcher::SwitcherController::CompareSwitcherItemsPriority,
I've tried print the value when specific the frame #2 in gdb,
print first->Type() will return me an actual ApplicationType
but print second->Type() will cause me a segmentation fault.
I'm running on the 4.28.0-0ubuntu2 unity so I think this issue is new.

ProblemType: Bug
DistroRelease: Ubuntu 11.10
Package: unity 4.28.0-0ubuntu2
ProcVersionSignature: Ubuntu 3.0.0-12.20-generic 3.0.4
Uname: Linux 3.0.0-12-generic x86_64
ApportVersion: 1.23-0ubuntu4
Architecture: amd64
CompizPlugins: [core,bailer,detection,composite,opengl,compiztoolbox,decor,mousepoll,regex,vpswitch,imgpng,resize,move,gnomecompat,wall,place,session,grid,snap,unitymtgrabhandles,animation,workarounds,expo,fade,scale,ezoom,unityshell]
Date: Mon Mar 5 17:21:45 2012
InstallationMedia: Ubuntu 11.04 "Natty Narwhal" - Beta amd64 (20110413)
SourcePackage: unity
UpgradeStatus: No upgrade log present (probably fresh install)

Revision history for this message
Tim Chen (timchen119) wrote :
Bilal Akhtar (bilalakhtar)
summary: - alt+tab makes unity crashed (with gdb logs)
+ [Oneiric] alt+tab makes unity crashed (with gdb logs)
Changed in unity (Ubuntu):
status: New → Triaged
Bilal Akhtar (bilalakhtar)
Changed in unity:
status: New → Triaged
importance: Undecided → High
Changed in unity (Ubuntu):
importance: Undecided → High
Changed in unity:
milestone: none → 4.30.0
Revision history for this message
DUVAL Jean-Pierre (jp-duval) wrote :

I think I have the same problem with Alt-Tab.
-------------------------------------------------------------
The first Alt-Tab makes crash compiz but the system respawns it automatically. But the Ubuntu desktop is a bit broken.
The second Alt-Tab (30 seconds later for example) makes crash both compiz and the Ubuntu desktop.

ON Ubuntu 11.0, Compiz 0.9.6, NVidia G96 [GeForce 9600M GS] (driver=nvidia)

It is terriblely anoying.

Here is the syslog extract :
Mar 6 10:40:42 jpd-ubuntu kernel: [ 2301.321926] compiz[1859]: segfault at 401 ip 00000401 sp bf999acc error 14 in compiz[8048000+77000]
Mar 6 10:40:42 jpd-ubuntu gnome-session[1775]: WARNING: Application 'compiz.desktop' killed by signal
Mar 6 10:40:42 jpd-ubuntu gnome-session[1775]: WARNING: App 'compiz.desktop' respawning too quickly
Mar 6 10:40:54 jpd-ubuntu kernel: [ 2314.041854] compiz[25427]: segfault at bb591 ip b3c1d091 sp bfa7fc30 error 4 in libunityshell.so[b3a9e000+20e000]
Mar 6 10:40:55 jpd-ubuntu gnome-session[1775]: WARNING: App 'compiz.desktop' respawning too quickly
Mar 6 10:40:55 jpd-ubuntu gnome-session[1775]: WARNING: Application 'compiz.desktop' killed by signal
Mar 6 10:40:55 jpd-ubuntu gnome-session[1775]: WARNING: App 'compiz.desktop' respawning too quickly
Mar 6 10:42:58 jpd-ubuntu kernel: [ 77.187104] compiz[1794]: segfault at b75b9 ip b3c2d091 sp bfdb2670 error 4 in libunityshell.so[b3aae000+20e000]
Mar 6 10:42:58 jpd-ubuntu gnome-session[1636]: WARNING: Application 'compiz.desktop' killed by signal
Mar 6 10:42:58 jpd-ubuntu gnome-session[1636]: WARNING: App 'compiz.desktop' respawning too quickly
Mar 6 10:43:05 jpd-ubuntu kernel: [ 84.531431] compiz[2080]: segfault at 2e3120a8 ip b3bd5096 sp bfe19d60 error 4 in libunityshell.so[b3a56000+20e000]
Mar 6 10:43:06 jpd-ubuntu gnome-session[1636]: WARNING: App 'compiz.desktop' respawning too quickly
Mar 6 10:43:06 jpd-ubuntu gnome-session[1636]: WARNING: Application 'compiz.desktop' killed by signal
Mar 6 10:43:06 jpd-ubuntu gnome-session[1636]: WARNING: App 'compiz.desktop' respawning too quickly

Revision history for this message
Tim Chen (timchen119) wrote :

Attached another gdb log from a private oem machine.
seems unity::switcher::SwitcherModel::SwitcherModel() also cause a seg fault too.

Omer Akram (om26er)
Changed in unity (Ubuntu Oneiric):
importance: Undecided → High
status: New → Triaged
Revision history for this message
Jens Finkhäuser (finkhaeuser-consulting) wrote :

I'm having something similar; I haven't looked for crashes, but my windows get re-arranged randomly across the desktops. It's quite possible that unity crashes and restarts, and that's what's causing the re-arrangement.

Revision history for this message
Serhiy (xintx-ua) wrote :

In my case it appeared only after some configurations changes with ccsm. Will try to reset everything and reproduce.

Revision history for this message
Serhiy (xintx-ua) wrote :

The simplest workaround is
$ unity --reset

And the exact steps for reproducing are
1. Launch ccsm
2. Uncheck Animations and Fading Windows.
3. Press Alt+Tab.

Revision history for this message
Michael Likholet (mlih) wrote :

Ubuntu 11.10, 64-bit. I'm just pressing "alt" key after login and got this crash quickly. Only unity crashes, all the applications remain visible on the screen and all the controls on them are clickable, but they contains no outer border and they cannot be moved.

"Good" workaround: No.
"Bad" workaround: pkill -9 gnome or something similar solves the problem.

Revision history for this message
Serhiy (xintx-ua) wrote :

Michael, have you tried "unity --reset" ?

Revision history for this message
Duane (duanedan) wrote :

I solved this task doing this: i oppened compizconfig, oppened ubuntu unity plugin, on switcher changed the key to start switcher from ALT TAb to ALT D.
That solved for me.

James M. Leddy (jm-leddy)
Changed in oem-priority:
importance: Undecided → Medium
Revision history for this message
Giovanni Luca Ciampaglia (gciampaglia) wrote :

Hi, I have the same problem and Duane's fix worked for me, changing ALT-TAB -> ALT-D doesn't crash unity.

Revision history for this message
Cson (theceason) wrote :

when crashing
i sometime even cant use the keybroad

Revision history for this message
Tim Chen (timchen119) wrote :

Upgrade to precise and I don't have this issue anymore.

James M. Leddy (jm-leddy)
Changed in oem-priority:
assignee: nobody → James M. Leddy (jm-leddy)
status: New → Won't Fix
Revision history for this message
Omer Akram (om26er) wrote :

closing the bug per TIm' comment. since we are not sure what exactly fixed it I'll set the precise task as wontfix.

Changed in unity:
status: Triaged → Fix Released
status: Fix Released → Invalid
Changed in unity (Ubuntu):
status: Triaged → Invalid
Changed in unity (Ubuntu Oneiric):
status: Triaged → Won't Fix
Revision history for this message
Daniel van Vugt (vanvugt) wrote :

I'm assuming this was fixed either in bug 916879, or bug 975168.

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