[PATCH] drm/ttm: Fix a regression causing kernel oops'es

[Zack Rusin]

From: Zack Rusin <zackr at vmware.com>

The branch is explicitly taken if ttm == NULL which means that to avoid
a null pointer reference the ttm object can not be used inside. Switch
back to dst_mem to avoid kernel oops'es.

This fixes kernel oops'es with any buffer objects which don't have ttm_tt,
e.g. with vram based screen objects on vmwgfx.

Signed-off-by: Zack Rusin <zackr at vmware.com>
Fixes: e3c92eb4a84f ("drm/ttm: rework on ttm_resource to use size_t type")
Cc: Somalapuram Amaranath <Amaranath.Somalapuram at amd.com>
Cc: Christian König <christian.koenig at amd.com>
---
 drivers/gpu/drm/ttm/ttm_bo_util.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/ttm/ttm_bo_util.c b/drivers/gpu/drm/ttm/ttm_bo_util.c
index fee7c20775c0..12017ec24d9f 100644
--- a/drivers/gpu/drm/ttm/ttm_bo_util.c
+++ b/drivers/gpu/drm/ttm/ttm_bo_util.c
@@ -183,7 +183,7 @@ int ttm_bo_move_memcpy(struct ttm_buffer_object *bo,
 
 	clear = src_iter->ops->maps_tt && (!ttm || !ttm_tt_is_populated(ttm));
 	if (!(clear && ttm && !(ttm->page_flags & TTM_TT_FLAG_ZERO_ALLOC)))
-		ttm_move_memcpy(clear, ttm->num_pages, dst_iter, src_iter);
+		ttm_move_memcpy(clear, PFN_UP(dst_mem->size), dst_iter, src_iter);
 
 	if (!src_iter->ops->maps_tt)
 		ttm_kmap_iter_linear_io_fini(&_src_iter.io, bdev, src_mem);
-- 
2.37.2