linux-kernel - [PATCH] drm/ttm: Make sure BOs being swapped out are cacheable

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Date:   Wed, 25 Jan 2017 17:21:31 +0900
From:   Michel Dänzer <michel@...nzer.net>
To:     Christian König <christian.koenig@....com>
Cc:     dri-devel@...ts.freedesktop.org, Sinclair Yeh <syeh@...are.com>,
        Thomas Hellstrom <thellstrom@...are.com>,
        linux-kernel@...r.kernel.org
Subject: [PATCH] drm/ttm: Make sure BOs being swapped out are cacheable

From: Michel Dänzer <michel.daenzer@....com>

The current caching state may not be tt_cached, even though the
placement contains TTM_PL_FLAG_CACHED, because placement can contain
multiple caching flags. Trying to swap out such a BO would trip up the

	BUG_ON(ttm->caching_state != tt_cached);

in ttm_tt_swapout.

Cc: stable@...r.kernel.org
Signed-off-by: Michel Dänzer <michel.daenzer@....com>
---
 drivers/gpu/drm/ttm/ttm_bo.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c
index d5063618efa7..86e3b233b722 100644
--- a/drivers/gpu/drm/ttm/ttm_bo.c
+++ b/drivers/gpu/drm/ttm/ttm_bo.c
@@ -1670,7 +1670,6 @@ static int ttm_bo_swapout(struct ttm_mem_shrink *shrink)
 	struct ttm_buffer_object *bo;
 	int ret = -EBUSY;
 	int put_count;
-	uint32_t swap_placement = (TTM_PL_FLAG_CACHED | TTM_PL_FLAG_SYSTEM);
 
 	spin_lock(&glob->lru_lock);
 	list_for_each_entry(bo, &glob->swap_lru, swap) {
@@ -1701,7 +1700,8 @@ static int ttm_bo_swapout(struct ttm_mem_shrink *shrink)
 	 * Move to system cached
 	 */
 
-	if ((bo->mem.placement & swap_placement) != swap_placement) {
+	if (bo->mem.mem_type != TTM_PL_SYSTEM ||
+	    bo->ttm->caching_state != tt_cached) {
 		struct ttm_mem_reg evict_mem;
 
 		evict_mem = bo->mem;
-- 
2.11.0