https://bugs.freedesktop.org/show_bug.cgi?id=104082
--- Comment #21 from Christian König ckoenig.leichtzumerken@gmail.com --- (In reply to Stratos Zolotas from comment #20)
Maybe it is a coincidence, for sure I'm not running out of memory when it is happening and started with kernel 4.15 and (or) Mesa 18.0 without any change on Virtualbox side. I'll wait for the fix to see what happens...
Well the message means that we ran out of memory to allocate a 2MB block and instead use many small 4K blocks.
What could be is that there is a memory leak somewhere triggering both the message and the VM faults you are seeing.