For questions and issues with the Mesa driver, your best options are:
I suggest that you open a Bugzilla ticket with the information in this post. The team will probably then ask you a lot of clarifying questions (OS? gpu pci id? Mesa version? etc etc).
Also, it's often helpful to directly contact the owner of the Mesa package for your Linux distribution. Sometimes the package owner is very familiar with frequent bugs that are specific to that distribution. On RPM based distros, such as Fedora, you can find the packager by examining the package's changelog with this command: `rpm -q --changelog mesa-libGL`. On Debian based distros, such as Ubuntu, I think the apt-cache command gives you the needed info.