compiz crashed with SIGSEGV in intel_miptree_release()

[Rosca Stefan]

White square appeared in left bottom corner of the screen (apr. 50px *50px). Only mouse pointer could overlay that square. If clicking workspace switcher the square was shown only on current workspace but switching to another cause square to move to that workspace. The window controls and Dash worked even if they were under the square. On attempt to drag a maximized window the mouse pointer transforms in a hand but after left mouse button release the pointer didn't change to normal state and compiz crashed. After a relaunch of compiz the white square dissapeared and system seems to work properly.

ProblemType: Crash
DistroRelease: Ubuntu 12.04
Package: unity 5.6.0-0ubuntu4
Uname: Linux 3.3.0-rc6 x86_64
ApportVersion: 1.94.1-0ubuntu2
Architecture: amd64
Date: Sat Mar 17 11:24:05 2012
ExecutablePath: /usr/bin/compiz
InstallationMedia: Ubuntu 11.10 "Oneiric Ocelot" - Release amd64 (20111012)
ProcCmdline: compiz
ProcEnviron:
 LANG=en_US.UTF-8
 SHELL=/bin/bash
SegvAnalysis:
 Segfault happened at: 0x7f6d2f2a75a9 <intel_miptree_release+9>: mov (%rdi),%rcx
 PC (0x7f6d2f2a75a9) ok
 source "(%rdi)" (0x00000220) not located in a known VMA region (needed readable region)!
 destination "%rcx" ok
SegvReason: reading NULL VMA
Signal: 11
SourcePackage: unity
StacktraceTop:
 intel_miptree_release () from /usr/lib/x86_64-linux-gnu/dri/i965_dri.so
 intel_update_renderbuffers () from /usr/lib/x86_64-linux-gnu/dri/i965_dri.so
 intelSetTexBuffer2 () from /usr/lib/x86_64-linux-gnu/dri/i965_dri.so
 TfpTexture::bindPixmapToTexture(unsigned long, int, int, int) () from /usr/lib/compiz/libopengl.so
 boost::detail::function::function_invoker4<GLTexture::List (*)(unsigned long, int, int, int), GLTexture::List, unsigned long, int, int, int>::invoke(boost::detail::function::function_buffer&, unsigned long, int, int, int) () from /usr/lib/compiz/libopengl.so
Title: compiz crashed with SIGSEGV in intel_miptree_release()
UpgradeStatus: Upgraded to precise on 2012-02-09 (36 days ago)
UserGroups: adm admin cdrom dialout lpadmin plugdev sambashare

[Apport retracing service (apport)]

Thank you for taking the time to report this crash and helping to make this software better. This particular crash has already been reported and is a duplicate of bug #926379, so is being marked as such. Please look at the other bug report to see if there is any missing information that you can provide, or to see if there is a workaround for the bug. Additionally, any further discussion regarding the bug should occur in the other report. Please continue to report any other bugs you may find.