https://bugs.freedesktop.org/show_bug.cgi?id=61182
--- Comment #27 from Knut Andre Tidemann knut.tidemann@gmail.com --- I've bisected the issue to this commit:
35840ab189595b817fa8b1a1df8cc92474a7c38d st/dri: implement MSAA for GLX/DRI2 framebuffers
The only thing that was recompiled was mesa, with the following options:
--with-dri-driverdir=/usr/lib/xorg/modules/dri --with-gallium-drivers=r600,swrast --with-dri-drivers= --with-egl-platforms=drm,x11 --enable-gallium-egl --enable-shared-glapi --enable-gallium-llvm --enable-glx-tls --enable-gles1 --enable-gles2 --enable-egl --enable-dri --enable-glx --enable-xa --enable-osmesa --enable-gbm --enable-texture-float
The issue was triggered by restarting kwin (kwin --replace) between each compile and locking and unlocking the screen.