compiz crashed with SIGSEGV in memmove() from drisw_update_tex_buffer() from dri_set_tex_buffer2() from drisw_bind_tex_image() from __glXBindTexImageEXT() from TfpTexture::enable() from enableFragmentOperationsAndDrawGeometry()

StacktraceTop:
 drisw_update_tex_buffer (drawable=0xad5dee60, ctx=0x9748cc0, res=0xaf712d00) at /usr/include/i386-linux-gnu/bits/string3.h:58
 dri_set_tex_buffer2 (pDRICtx=0x9751610, target=3553, format=8410, dPriv=0xad314358) at dri_drawable.c:230
 drisw_bind_tex_image (dpy=0x96ff058, drawable=18874771, buffer=8414, attrib_list=0x0) at drisw_glx.c:316
 __glXBindTexImageEXT (dpy=0x96ff058, drawable=18874771, buffer=8414, attrib_list=0x0) at glxcmds.c:2429
 TfpTexture::enable (this=0xad522708, filter=GLTexture::Fast) at /build/buildd/compiz-0.9.6+bzr20110929/plugins/opengl/src/texture.cpp:602

Status changed to 'Confirmed' because the bug affects multiple users.

Looks like a bug in the software renderer.

(To clarify, NULL is valid for glXBindTexImageEXT)

If the bug is in another package then we need to be sure, and then reassign it. It's not helpful to anyone to mark the bug as invalid in all projects.

Although with several potential sources of heap corruption now fixed in Unity 5.12, we might find this bug stops occurring. Fingers crossed.

Seems with the introduction of LLVMpipe support in Ubuntu 12.10, this bug is now happening to a lot more people than it was in 12.04.

Bump priority. I'm seeing a flood of duplicates to this now, from LLVMpipe users (Ubuntu 12.10).

Possible work around: Changing screen resolution ??

I first encountered the problem when I was in the process of installing a big pile of
updates using aptitude... (see Bug #1040774)

    Then the UI began behaving all wacky. Everything started flashing
    black every time I moved the mouse. Menus were positioned in the wrong
    places, Could not reposition windows on the UI. It was very difficult
    to see the windows inside the GU layers. This made Quantal practically unusable
    because because it would only correctly respond to about 1% of the mouse clicks.

It turns out that during the upgrade my screen resolution was changed to 3840x1920 ( the first one in the pick list). I run Quantal on VMware® Workstation 8.0.4 build-744019. In the Systems-Settings => Displays I now see 'Laptop' where I used to see 'Unknown'. Perhaps this is the new default.

Anyway after editing the xorg.conf file with nano and setting the display resolution back to 1920 x 1200 - everything seems fine.

I had the same situation described in comment #12, and changing screen resolution, even down to 1024x768, didn't help much. It did reduce the flashing and black screen, but not enough to make it really usable. So I think that reducing screen resolution makes the problem "less bad", not actually better.

That having been said, with the latest (as of Aug 29) updates, the black screen and display artifact issues went away, and when Compiz crashes, Unity manages to restart itself after a short delay, so the machine isn't completely unusable.

I filed dupe bug #1043938 and this happens very frequently when closing an application via the 'x' button on the title bar in an up to date 12.10 VM using qemu-kvm.

Forget what I said in #12 (changing screen resolution didnt stop it - still happening as of Bug #1044454 [unity 6.2.0-0ubuntu4 ; Ubuntu 3.2.0-12.21-generic 3.2.2 ). Although I agree with jdreed in #13 it is way more stable than before.

This bug has been reported on the Ubuntu ISO testing tracker.

A list of all reports related to this bug can be found here:
http://iso.qa.ubuntu.com/qatracker/reports/bugs/927168

The "flashing and black screen" was bug 1021104. It should be treated separately, although it certainly would have happened on VMs where this bug is happening.

As we don't know if the issue is in mesa or compiz, Daniel, Timo, can you work together to figure that out? Thanks!

All the readable stacks I have found so far have shown the problem originating from either:
  DecorTexture::DecorTexture
or
  DecorWindow::glDecorate

Assigning to smspillaz. He knows a lot more about the decor texturing which seems to be the problem here.

Some of the most readable stacks from recent duplicates:
https://launchpadlibrarian.net/115551011/Stacktrace.txt
https://launchpadlibrarian.net/115545323/Stacktrace.txt
https://launchpadlibrarian.net/115549285/Stacktrace.txt
https://launchpadlibrarian.net/115587684/Stacktrace.txt
https://launchpadlibrarian.net/115563588/Stacktrace.txt
https://launchpadlibrarian.net/115553644/Stacktrace.txt

Confirmed in Mesa again. I'm not 100% sure this is only the fault of compiz/decor. I've just reproduced a similar crash with LLVMpipe, but slightly different below drisw_update_tex_buffer.

smspillaz:
Would it make sense to keep the pixmap allocation in the decorator, but move all pixmap frees into the decor plugin? That should ensure any pixmap passed to decor is still valid. Assuming that is the problem.

Yes, that will work, however we'll need to be careful about not leaking in the decorator in that case. That will probably involve compiz creating a session window as well for the decorator, which isn't a difficult task

sorry, leaking the pixmap.

Set to Medium in compiz-core (precise) and Critical in compiz (quantal). That's because almost no one will ever see this bug in precise. LLVMpipe is only widely used in quantal compiz 0.9.8.*

Removing the quantal task, we have a workaround in compiz now.

This bug was fixed in the package compiz - 1:0.9.8.2+bzr3377-0ubuntu1

---------------
compiz (1:0.9.8.2+bzr3377-0ubuntu1) quantal-proposed; urgency=low

  [ Sam Spilsbury ]
  * debian/python-compizconfig.install
    - Install compizconfig-python.pc
  * debian/patches/100_expo_layout.patch
    - re-add the expo layout that used to be in precise (LP: #1047067)
    - add some testcases

  [ Timo Jyrinki ]
  * New upstream snapshot.
    - Fix multiple window placement bugs (LP: #974242) (LP: #976032)
    - Don't waste CPU looping through and looking at all the windows if you're
      rendering an output that has no damage on it. (LP: #1014986)
    - Updated convert files to fix some typos in the key names. (LP: #1041631)
    - Fix crash when imgsvg is loaded, due to missing symbol
      (decor_apply_gravity from libdecoration). (LP: #956986)
    - Treat unresolved symbols at link time as an error, rather than letting
      them through and cause strange crashes later. (LP: #1043143)
    - Refactors a little bit of the upgrade code and gets it under test to
      prepare to fix (LP: #1042537)
    - Updated AUTHORS from the full bzr log, and re-sort the list.
      (LP: #1042095)
    - Fixes FTBFS for kde4-window-decorator (LP: #1041310)
    - Fix obvious omissions from the introduction of unminimize_*,
      which were causing the unminimize animation settings to be ignored
      (LP: #1040455)
    - resize plugin: don't crash if resize wasn't initiated externally
      (LP: #1045191)
    - Clean up capitalization (LP: #1045652)
    - Avoid division by zero, if plugins try to deform a window down to size
      zero. (LP: #1045235)
    - Make "Unredirect Fullscreen Windows" more reliable. This fixes the
      problem with unredirection failing to engage at all (LP: #1041066) when
      gtk-window-decorator creates offscreen windows that are stacked on top.
      This also fixes the problem with unredirect hiding all windows,
      because it thinks the desktop window should be stacked on top
      (LP: #980663).
    - Ensure unredirected windows don't stay unredirected if they're no longer
      on top. (LP: #1041047)
    - Fix launching terminal functionality and make show-hud default key
      visible. Update the defaults to org.compiz.integrated to reflect the
      actual gnome values pre-gnome-3. (LP: #1040081) (LP: #1046199)
      (LP: #1046190)
    - Fix show-hud, bump COMPIZ_GNOME_INTEGRATED_SETTINGS_LIST_SIZE.
      (LP: #1046212)
    - Fixed: Windows with an alpha-channel, like gnome-terminal, were not
      being considered as possibly covering fullscreen windows. But they most
      certainly can. This ensures such RGBA windows are visible if they're
      stacked above a fullscreen window. (LP: #1046661)
    - Remove ListToStringList (LP: #1046184)
    - Fix typo causing CMake Error (LP: #1045665)
    - Transitions gtk-window-decorator over to use GSettings. Add a testing
      framework for the options code. (LP: #1042323)
    - Also need kdeworkspace since kdecorationbridge.h is there
      (LP: #1046770)
    - Implements some cleanup that was suggested on the merge for the original
      port to gsettings. Other issues fixed as wel...

lowering the mesa bug priority, since it's worked around in compiz.

My own build of Blender that OSL support is enabled crashes on startup in Virtualbox.

Attached a backtrace.

irie:

That's not directly related to this bug. Please log a new bug using this command:
    ubuntu-bug blender

Thanks, Daniel.

I reported my Blender issue in Blender bug tracker.