I faced with something similar.. Here is my related dmesg output:
[ 723.041613] show_signal_msg: 15 callbacks suppressed [ 723.041621] compiz[10514]: segfault at 71 ip 00007f11c6eb0565 sp 00007fff84340770 error 4 in libunityshell.so[7f11c6db4000+225000] [ 902.798182] compiz[14654]: segfault at 0 ip (null) sp 00007fff26d67b08 error 14 in compiz[400000+7c000] [ 969.040926] compiz[14789]: segfault at f8 ip 00007fc6ecd4e56c sp 00007fff8772c4d0 error 4 in libunityshell.so[7fc6ecc52000+225000] -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/904086 Title: compiz kernel null pointer mutex_lock To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/compiz/+bug/904086/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
