Am 03.09.21 um 08:49 schrieb Pan, Xinhui:

The ret value might be -EBUSY, caller will think lru lock is still locked but actually NOT. So return -ENOSPC instead. Otherwise we hit list corruption.

ttm_bo_cleanup_refs might fail too if BO is not idle. If we return 0, caller(ttm_tt_populate -> ttm_global_swapout ->ttm_device_swapout) will be stuck as we actually did not free any BO memory. This usually happens when the fence is not signaled for a long time.

Signed-off-by: xinhui pan xinhui.pan@amd.com

Good catch, wanted to rework this for a very long time because of potential bugs like those.

Reviewed-by: Christian König christian.koenig@amd.com

---

drivers/gpu/drm/ttm/ttm_bo.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c index 1fedd0eb67ba..f1367107925b 100644 --- a/drivers/gpu/drm/ttm/ttm_bo.c +++ b/drivers/gpu/drm/ttm/ttm_bo.c @@ -1159,9 +1159,9 @@ int ttm_bo_swapout(struct ttm_buffer_object *bo, struct ttm_operation_ctx *ctx, }

if (bo->deleted) {

• ttm_bo_cleanup_refs(bo, false, false, locked);
  

• ret = ttm_bo_cleanup_refs(bo, false, false, locked);
  

  ttm_bo_put(bo);

• return 0;
  

• return ret == -EBUSY ? -ENOSPC : ret;
  

  }

  ttm_bo_move_to_pinned(bo);

@@ -1215,7 +1215,7 @@ int ttm_bo_swapout(struct ttm_buffer_object *bo, struct ttm_operation_ctx *ctx, if (locked) dma_resv_unlock(bo->base.resv); ttm_bo_put(bo);

• return ret;

• return ret == -EBUSY ? -ENOSPC : ret; }

  void ttm_bo_tt_destroy(struct ttm_buffer_object *bo)