[PATCH] drm/ttm: Fix the memory delay free issue

[Chunming Zhou]

It doesn't make sense that freeing BO still uses per-vm resv.

I remember when BO is in release list, its resv will be from per-vm resv 
copy. Could you check it?

-David

在 2019/7/10 17:29, Emily Deng 写道:
> For vulkan cts allocation test cases, they will create a series of bos, and then free
> them. As it has lots of alloction test cases with the same vm, as per vm
> bo feature enable, all of those bos' resv are the same. But the bo free is quite slow,
> as they use the same resv object, for every time, free a bo,
> it will check the resv whether signal, if it signal, then will free it. But
> as the test cases will continue to create bo, and the resv fence is increasing. So the
> free is more slower than creating. It will cause memory exhausting.
>
> Method:
> When the resv signal, release all the bos which are use the same
> resv object.
>
> Signed-off-by: Emily Deng <Emily.Deng at amd.com>
> ---
>   drivers/gpu/drm/ttm/ttm_bo.c | 29 ++++++++++++++++++++++++-----
>   1 file changed, 24 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c
> index f9a3d4c..57ec59b 100644
> --- a/drivers/gpu/drm/ttm/ttm_bo.c
> +++ b/drivers/gpu/drm/ttm/ttm_bo.c
> @@ -543,6 +543,7 @@ static int ttm_bo_cleanup_refs(struct ttm_buffer_object *bo,
>   {
>   	struct ttm_bo_global *glob = bo->bdev->glob;
>   	struct reservation_object *resv;
> +	struct ttm_buffer_object *resv_bo, *resv_bo_next;
>   	int ret;
>   
>   	if (unlikely(list_empty(&bo->ddestroy)))
> @@ -566,10 +567,14 @@ static int ttm_bo_cleanup_refs(struct ttm_buffer_object *bo,
>   							   interruptible,
>   							   30 * HZ);
>   
> -		if (lret < 0)
> +		if (lret < 0) {
> +			kref_put(&bo->list_kref, ttm_bo_release_list);
>   			return lret;
> -		else if (lret == 0)
> +		}
> +		else if (lret == 0) {
> +			kref_put(&bo->list_kref, ttm_bo_release_list);
>   			return -EBUSY;
> +		}
>   
>   		spin_lock(&glob->lru_lock);
>   		if (unlock_resv && !kcl_reservation_object_trylock(bo->resv)) {
> @@ -582,6 +587,7 @@ static int ttm_bo_cleanup_refs(struct ttm_buffer_object *bo,
>   			 * here.
>   			 */
>   			spin_unlock(&glob->lru_lock);
> +			kref_put(&bo->list_kref, ttm_bo_release_list);
>   			return 0;
>   		}
>   		ret = 0;
> @@ -591,15 +597,29 @@ static int ttm_bo_cleanup_refs(struct ttm_buffer_object *bo,
>   		if (unlock_resv)
>   			kcl_reservation_object_unlock(bo->resv);
>   		spin_unlock(&glob->lru_lock);
> +		kref_put(&bo->list_kref, ttm_bo_release_list);
>   		return ret;
>   	}
>   
>   	ttm_bo_del_from_lru(bo);
>   	list_del_init(&bo->ddestroy);
>   	kref_put(&bo->list_kref, ttm_bo_ref_bug);
> -
>   	spin_unlock(&glob->lru_lock);
>   	ttm_bo_cleanup_memtype_use(bo);
> +	kref_put(&bo->list_kref, ttm_bo_release_list);
> +
> +	spin_lock(&glob->lru_lock);
> +	list_for_each_entry_safe(resv_bo, resv_bo_next, &bo->bdev->ddestroy, ddestroy) {
> +		if (resv_bo->resv == bo->resv) {
> +			ttm_bo_del_from_lru(resv_bo);
> +			list_del_init(&resv_bo->ddestroy);
> +			spin_unlock(&glob->lru_lock);
> +			ttm_bo_cleanup_memtype_use(resv_bo);
> +			kref_put(&resv_bo->list_kref, ttm_bo_release_list);
> +			spin_lock(&glob->lru_lock);
> +		}
> +	}
> +	spin_unlock(&glob->lru_lock);
>   
>   	if (unlock_resv)
>   		kcl_reservation_object_unlock(bo->resv);
> @@ -639,9 +659,8 @@ static bool ttm_bo_delayed_delete(struct ttm_bo_device *bdev, bool remove_all)
>   			ttm_bo_cleanup_refs(bo, false, !remove_all, true);
>   		} else {
>   			spin_unlock(&glob->lru_lock);
> +			kref_put(&bo->list_kref, ttm_bo_release_list);
>   		}
> -
> -		kref_put(&bo->list_kref, ttm_bo_release_list);
>   		spin_lock(&glob->lru_lock);
>   	}
>   	list_splice_tail(&removed, &bdev->ddestroy);