This seems like an impressive improvement, and I'm looking forward to it eventually being upstreamed. Though unfortunately I'm on Nvidia right now, and have been struggling with vram. They don't seem to support any kind of paging at all.

I am curious about the bit on virtual memory fragmentation. Would it make sense for the kernel to occasionally defragment that memory in place? I assume that would create a noticeable hitch, but might improve performance otherwise and allow for some applications to just fit in.