[Intel-gfx] [PATCH 01/24] Revert "drm/i915/gem: Async GPU relocations only"

[Chris Wilson]

Quoting Maarten Lankhorst (2020-08-10 11:30:40)
> This reverts commit 9e0f9464e2ab36b864359a59b0e9058fdef0ce47,
> and related commit 7ac2d2536dfa7 ("drm/i915/gem: Delete unused code").
> 
> Async GPU relocations are not the path forward, we want to remove
> GPU accelerated relocation support eventually when userspace is fixed
> to use VM_BIND, and this is the first step towards that. We will keep
> async gpu relocations around for now, until userspace is fixed.

As it stands you are exposing an attack vector with your code that
allows one user to create an arbitrary lock holdtime and to pass that
lock onto a high priority consumer forcing them to wait upon you.

You may keep on denying that, and also keep denying that you have been
shown the bug and how to avoid it.
-Chris