Intel GPU memory corruption

[Baltazár Radics]

Hello!

I have a Lenovo Thinkpad T460 with an integrated `Intel Corporation
Skylake GT2 [HD Graphics 520]` GPU. Whenever there's intensive usage of
it, after a while I experience memory corruption. Under normal usage,
this results in random programs segfaulting for example.

I have done several memory tests, including the Lenovo hardware
diagnostics included with my BIOS and the userspace utility `memtester`
as well. When the GPU is not used, no tests have found any issues, so
I'm fairly certain my actual RAM sticks are fine.

However, when I run e.g. `vkmark` or `mpv` alongside `memtester`, it
will report issues after one or two loops. During the time I ran it,
all failures happened at the same offset.

Based on this, I suspect the video driver is the culprit somehow, but
I'm still not entirely certain it's not a hardware issue. If anyone has
ideas on how to track this down, I'd be happy to do some tests.