Chris seems to have correctly identified the issue. I tried reverting the xserver-xorg-video-intel to previous versions, but it had no affect.
I rebooted into an older kernel and i can still use compiz/unity. 3.16.0-6-generic : works 3.16.0-7-generic : fails 3.16.0-8-generic: fails ** Summary changed: - unity crashes on login, compiz cpu and memory intensive + compiz fails with intel_do_flush_locked failed: Invalid argument ** No longer affects: unity (Ubuntu) -- You received this bug notification because you are a member of DX Packages, which is subscribed to unity in Ubuntu. Matching subscriptions: dx-packages https://bugs.launchpad.net/bugs/1355196 Title: compiz fails with intel_do_flush_locked failed: Invalid argument Status in “linux” package in Ubuntu: Confirmed Status in “xserver-xorg-video-intel” package in Ubuntu: New Bug description: Recent upgrade and reboot/re-login left me with a generally unusable compiz/unity. On login, the desktop icons move back and forth several times, I believe this correlates with ~/.xesssion-errors 'unity main process ended' messages like: upstart: unity7 main process (7477) terminated with status 1 upstart: unity7 main process ended, respawning upstart: unity7 main process (7910) terminated with status 1 upstart: unity7 main process ended, respawning upstart: unity7 main process (7939) terminated with status 1 Further investigation showed that compiz was failing to start. Attempting to start it by hand shows: intel_do_flush_locked failed: Invalid argument Those same messages appear in ~/.cache/upstart/unity7.log. ProblemType: Bug DistroRelease: Ubuntu 14.10 Package: unity 7.3.0+14.10.20140731.1-0ubuntu1 ProcVersionSignature: Ubuntu 3.16.0-6.11-generic 3.16.0-rc7 Uname: Linux 3.16.0-6-generic x86_64 ApportVersion: 2.14.5-0ubuntu4 Architecture: amd64 CompizPlugins: [core,bailer,detection,composite,opengl,compiztoolbox,decor,snap,commands,mousepoll,grid,move,place,imgpng,session,vpswitch,resize,regex,gnomecompat,unitymtgrabhandles,wall,resizeinfo,animation,workarounds,fade,scale,expo,ezoom,unityshell] CurrentDesktop: Unity Date: Mon Aug 11 09:53:07 2014 EcryptfsInUse: Yes InstallationDate: Installed on 2011-10-19 (1027 days ago) InstallationMedia: Ubuntu 11.10 "Oneiric Ocelot" - Release amd64 (20111012) SourcePackage: unity UpgradeStatus: Upgraded to utopic on 2013-05-20 (448 days ago) To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1355196/+subscriptions -- Mailing list: https://launchpad.net/~dx-packages Post to : dx-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~dx-packages More help : https://help.launchpad.net/ListHelp