Intel engineer Tvrtko Ursulin has been working on the ability to track per-client memory footprint and accounting to expose various memory metrics for a given process under /proc or there is also pending patches for then to conveniently summarize the GPU memory usage via gputop for showing memory use on a per-process basis.
On Monday the fourth iteration of these patches were posted that now make use of DRM GEM handles for tracking user objects and also a fix to the code.
It's interesting work and will be helpful to some wanting more insight over video memory use by processes. It's too bad such functionality wasn't in place universally for all Linux kernel graphics drivers long ago. Given the timing these updated patches they wouldn't be expected now until at least the v6.6 kernel cycle. Those wanting to try out these fdinfo memory statistics patches can find them on the dri-devel mailing list.