[PATCH 3.2 054/153] drm/ttm: Don't add swapped BOs to swap-LRU list

[Ben Hutchings]

3.2.102-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Felix Kuehling <Felix.Kuehling@xxxxxxx>

commit fd5002d6a3c602664b07668a24df4ef7a43bf078 upstream.

A BO that's already swapped would be added back to the swap-LRU list
for example if its validation failed under high memory pressure. This
could later lead to swapping it out again and leaking previous swap
storage.

This commit adds a condition to prevent that from happening.

v2: Check page_flags instead of swap_storage

Signed-off-by: Felix Kuehling <Felix.Kuehling@xxxxxxx>
Reviewed-by: Christian KÃnig <christian.koenig@xxxxxxx>
Signed-off-by: Alex Deucher <alexander.deucher@xxxxxxx>
[bwh: Backported to 3.2: We aren't checking for TTM_PAGE_FLAG_SG here as that's
 not defined]
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
--- a/drivers/gpu/drm/ttm/ttm_bo.c
+++ b/drivers/gpu/drm/ttm/ttm_bo.c
@@ -184,7 +184,7 @@ void ttm_bo_add_to_lru(struct ttm_buffer
 		list_add_tail(&bo->lru, &man->lru);
 		kref_get(&bo->list_kref);
 
-		if (bo->ttm != NULL) {
+		if (bo->ttm && !(bo->ttm->page_flags & TTM_PAGE_FLAG_SWAPPED)) {
 			list_add_tail(&bo->swap, &bo->glob->swap_lru);
 			kref_get(&bo->list_kref);
 		}