[PATCH] drm/xe: Keep walking on SVM eviction failure

[Matthew Brost <matthew.brost@intel.com>]

The desired behavior for SVM eviction failures, which can occur due to
various uncontrollable races, is for TTM to continue walking the LRU
list and look for another eviction candidate. This is expressed by
returning -ENOSPC from the ->move() callback.

Adjust the SVM eviction failure path in ->move() to return -ENOSPC so
that TTM continues searching for another buffer to evict.

Fixes: 3ca608dc7561 ("drm/xe: Basic SVM BO eviction")
Cc: stable@vger.kernel.org
Signed-off-by: Matthew Brost <matthew.brost@intel.com>
---
 drivers/gpu/drm/xe/xe_bo.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/gpu/drm/xe/xe_bo.c b/drivers/gpu/drm/xe/xe_bo.c
index b162753cebb7..8264b2ef557e 100644
--- a/drivers/gpu/drm/xe/xe_bo.c
+++ b/drivers/gpu/drm/xe/xe_bo.c
@@ -1043,6 +1043,11 @@ static int xe_bo_move(struct ttm_buffer_object *ttm_bo, bool evict,
 		} else {
 			drm_dbg(&xe->drm, "Evict system allocator BO failed=%pe\n",
 				ERR_PTR(ret));
+			/*
+			 * The semantic we want upon SVM eviction failure is
+			 * keep walking for eviction, which is -ENOSPC.
+			 */
+			ret = -ENOSPC;
 		}
 
 		goto out;
-- 
2.34.1