[RFC PATCH 0/2] mm,drm/ttm: Always block GUP to TTM pages

[Thomas Hellström (Intel)]

get_user_pages() to TTM pages is uwanted since TTM assumes it owns
the pages exclusively and / or sets up page-table mappings to io memory.

The first patch make sures we stop fast gup to huge TTM pages using
a trick with pmd_devmap() and pud_devmap() without a backing
dev_pagemap.

The second patch makes sure we block normal gup by setting VM_PFNMAP

Cc: Christian Koenig <christian.koenig@xxxxxxx>
Cc: David Airlie <airlied@xxxxxxxx>
Cc: Daniel Vetter <daniel@xxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Jason Gunthorpe <jgg@xxxxxxxxxx>
Cc: linux-mm@xxxxxxxxx
Cc: dri-devel@xxxxxxxxxxxxxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
Signed-off-by: Thomas Hellström (Intel) <thomas_os@xxxxxxxxxxxx>