Re: [PATCH 6/6] drm/ttm: Fix multihop assert on eviction.

Am 22.06.21 um 18:23 schrieb Andrey Grodzovsky:

Problem: Under memory pressure when GTT domain is almost full multihop assert will come up when trying to evict LRU BO from VRAM to SYSTEM.

Fix: Don't assert on multihop error in evict code but rather do a retry as we do in ttm_bo_move_buffer

Signed-off-by: Andrey Grodzovsky andrey.grodzovsky@amd.com

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

But I think you need to move this patch earlier in the series or otherwise you break amdgpu eviction in between.

Christian.

---

drivers/gpu/drm/ttm/ttm_bo.c | 63 +++++++++++++++++++----------------- 1 file changed, 34 insertions(+), 29 deletions(-)

diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c index 45145d02aed2..5a2dc712c632 100644 --- a/drivers/gpu/drm/ttm/ttm_bo.c +++ b/drivers/gpu/drm/ttm/ttm_bo.c @@ -485,6 +485,31 @@ void ttm_bo_unlock_delayed_workqueue(struct ttm_device *bdev, int resched) } EXPORT_SYMBOL(ttm_bo_unlock_delayed_workqueue);

+static int ttm_bo_bounce_temp_buffer(struct ttm_buffer_object *bo,

• 		     struct ttm_resource **mem,
  

• 		     struct ttm_operation_ctx *ctx,
  

• 		     struct ttm_place *hop)
  

+{

• struct ttm_placement hop_placement;
• struct ttm_resource *hop_mem;
• int ret;
• hop_placement.num_placement = hop_placement.num_busy_placement = 1;
• hop_placement.placement = hop_placement.busy_placement = hop;
• /* find space in the bounce domain */
• ret = ttm_bo_mem_space(bo, &hop_placement, &hop_mem, ctx);
• if (ret)

• return ret;
  

• /* move to the bounce domain */
• ret = ttm_bo_handle_move_mem(bo, hop_mem, false, ctx, NULL);
• if (ret) {

• ttm_resource_free(bo, &hop_mem);
  

• return ret;
  

• }
• return 0;

+}

• static int ttm_bo_evict(struct ttm_buffer_object *bo, struct ttm_operation_ctx *ctx) {

@@ -524,12 +549,17 @@ static int ttm_bo_evict(struct ttm_buffer_object *bo, goto out; }

+bounce: ret = ttm_bo_handle_move_mem(bo, evict_mem, true, ctx, &hop);

• if (unlikely(ret)) {

• WARN(ret == -EMULTIHOP, "Unexpected multihop in eviction - likely driver bug\n");
  

• if (ret != -ERESTARTSYS)
  

• if (ret == -EMULTIHOP) {

• ret = ttm_bo_bounce_temp_buffer(bo, &evict_mem, ctx, &hop);
  

• if (ret) {
  pr_err("Buffer eviction failed\n");
  

• ttm_resource_free(bo, &evict_mem);
  

• 	ttm_resource_free(bo, &evict_mem);
  

• 	goto out;
  

• }
  

• /* try and move to final place now. */
  

• goto bounce;
  

  } out: return ret;

@@ -844,31 +874,6 @@ int ttm_bo_mem_space(struct ttm_buffer_object *bo, } EXPORT_SYMBOL(ttm_bo_mem_space);

-static int ttm_bo_bounce_temp_buffer(struct ttm_buffer_object *bo,

• 		     struct ttm_resource **mem,
  

• 		     struct ttm_operation_ctx *ctx,
  

• 		     struct ttm_place *hop)
  

-{

• struct ttm_placement hop_placement;
• struct ttm_resource *hop_mem;
• int ret;
• hop_placement.num_placement = hop_placement.num_busy_placement = 1;
• hop_placement.placement = hop_placement.busy_placement = hop;
• /* find space in the bounce domain */
• ret = ttm_bo_mem_space(bo, &hop_placement, &hop_mem, ctx);
• if (ret)

• return ret;
  

• /* move to the bounce domain */
• ret = ttm_bo_handle_move_mem(bo, hop_mem, false, ctx, NULL);
• if (ret) {

• ttm_resource_free(bo, &hop_mem);
  

• return ret;
  

• }
• return 0;

-}

• static int ttm_bo_move_buffer(struct ttm_buffer_object *bo, struct ttm_placement *placement, struct ttm_operation_ctx *ctx)