The TTM LRU-walk cherry-pick series

[Thomas Hellström]

Christian, Matthew,

I think I addressed all review comments and a couple of anticipated
ones (s/long/s64/) in the swapout- and eviction patches.

I'm heading off on vacation today, (4 weeks) so if something becomes
urgent in-between feel free to pick up, modify and merge. 

Regarding the drm_exec trylock functionality I'm for as much as
possible that it should look like any other locking primitive trylock.
i.e. no additional tricks needed.

Thanks,
Thomas