drm/i915: use __GFP_RETRY_MAYFAIL

Commit 24f8e00a ("drm/i915: Prefer to report ENOMEM rather than
incur the oom for gfx allocations") has tried to remove disruptive OOM
killer because the userspace should be able to cope with allocation
failures.

At the time only __GFP_NORETRY could achieve that and it turned out that
this would fail the allocations just too easily.  So "drm/i915: Remove
__GFP_NORETRY from our buffer allocator" removed it and hoped for a
better solution.  __GFP_RETRY_MAYFAIL is that solution.  It will keep
retrying the allocation until there is no more progress and we would go
OOM.  Instead we fail the allocation and let the caller to deal with it.

Link: http://lkml.kernel.org/r/20170623085345.11304-6-mhocko@kernel.orgSigned-off-by: Michal Hocko <mhocko@suse.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Alex Belits <alex.belits@cavium.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Darrick J. Wong <darrick.wong@oracle.com>
Cc: David Daney <david.daney@cavium.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: NeilBrown <neilb@suse.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/gpu/drm/i915/i915_gem.c

@@ -2434,8 +2434,9 @@ i915_gem_object_get_pages_gtt(struct drm_i915_gem_object *obj)
 				 * again with !__GFP_NORETRY. However, we still
 				 * want to fail this allocation rather than
 				 * trigger the out-of-memory killer and for
-				 * this we want the future __GFP_MAYFAIL.
+				 * this we want __GFP_RETRY_MAYFAIL.
 				 */
+				gfp |= __GFP_RETRY_MAYFAIL;
 			}
 		} while (1);