drm/ttm: allocate resource object instead of embedding it v2

To improve the handling we want the establish the resource object as base
class for the backend allocations.

v2: add missing error handling

Signed-off-by: Christian König <christian.koenig@amd.com>
Acked-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210602100914.46246-1-christian.koenig@amd.com

11 files changed, 110 insertions, 126 deletions

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
index 03c6b63d1d54..59723c3d5826 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
@@ -362,14 +362,14 @@ int amdgpu_bo_create_kernel_at(struct amdgpu_device *adev,
 	if (cpu_addr)
 		amdgpu_bo_kunmap(*bo_ptr);
 
-	ttm_resource_free(&(*bo_ptr)->tbo, (*bo_ptr)->tbo.resource);
+	ttm_resource_free(&(*bo_ptr)->tbo, &(*bo_ptr)->tbo.resource);
 
 	for (i = 0; i < (*bo_ptr)->placement.num_placement; ++i) {
 		(*bo_ptr)->placements[i].fpfn = offset >> PAGE_SHIFT;
 		(*bo_ptr)->placements[i].lpfn = (offset + size) >> PAGE_SHIFT;
 	}
 	r = ttm_bo_mem_space(&(*bo_ptr)->tbo, &(*bo_ptr)->placement,
-			     (*bo_ptr)->tbo.resource, &ctx);
+			     &(*bo_ptr)->tbo.resource, &ctx);
 	if (r)
 		goto error;
 
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
index 663aa7d2e2ea..69db89261650 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
@@ -491,7 +491,7 @@ static int amdgpu_bo_move(struct ttm_buffer_object *bo, bool evict,
 			return r;
 
 		amdgpu_ttm_backend_unbind(bo->bdev, bo->ttm);
-		ttm_resource_free(bo, bo->resource);
+		ttm_resource_free(bo, &bo->resource);
 		ttm_bo_assign_mem(bo, new_mem);
 		goto out;
 	}
@@ -950,9 +950,9 @@ int amdgpu_ttm_alloc_gart(struct ttm_buffer_object *bo)
 	struct amdgpu_device *adev = amdgpu_ttm_adev(bo->bdev);
 	struct ttm_operation_ctx ctx = { false, false };
 	struct amdgpu_ttm_tt *gtt = (void *)bo->ttm;
-	struct ttm_resource tmp;
 	struct ttm_placement placement;
 	struct ttm_place placements;
+	struct ttm_resource *tmp;
 	uint64_t addr, flags;
 	int r;
 
@@ -962,37 +962,37 @@ int amdgpu_ttm_alloc_gart(struct ttm_buffer_object *bo)
 	addr = amdgpu_gmc_agp_addr(bo);
 	if (addr != AMDGPU_BO_INVALID_OFFSET) {
 		bo->resource->start = addr >> PAGE_SHIFT;
-	} else {
+		return 0;
+	}
 
-		/* allocate GART space */
-		placement.num_placement = 1;
-		placement.placement = &placements;
-		placement.num_busy_placement = 1;
-		placement.busy_placement = &placements;
-		placements.fpfn = 0;
-		placements.lpfn = adev->gmc.gart_size >> PAGE_SHIFT;
-		placements.mem_type = TTM_PL_TT;
-		placements.flags = bo->resource->placement;
-
-		r = ttm_bo_mem_space(bo, &placement, &tmp, &ctx);
-		if (unlikely(r))
-			return r;
+	/* allocate GART space */
+	placement.num_placement = 1;
+	placement.placement = &placements;
+	placement.num_busy_placement = 1;
+	placement.busy_placement = &placements;
+	placements.fpfn = 0;
+	placements.lpfn = adev->gmc.gart_size >> PAGE_SHIFT;
+	placements.mem_type = TTM_PL_TT;
+	placements.flags = bo->resource->placement;
 
-		/* compute PTE flags for this buffer object */
-		flags = amdgpu_ttm_tt_pte_flags(adev, bo->ttm, &tmp);
+	r = ttm_bo_mem_space(bo, &placement, &tmp, &ctx);
+	if (unlikely(r))
+		return r;
 
-		/* Bind pages */
-		gtt->offset = (u64)tmp.start << PAGE_SHIFT;
-		r = amdgpu_ttm_gart_bind(adev, bo, flags);
-		if (unlikely(r)) {
-			ttm_resource_free(bo, &tmp);
-			return r;
-		}
+	/* compute PTE flags for this buffer object */
+	flags = amdgpu_ttm_tt_pte_flags(adev, bo->ttm, tmp);
 
-		ttm_resource_free(bo, bo->resource);
-		ttm_bo_assign_mem(bo, &tmp);
+	/* Bind pages */
+	gtt->offset = (u64)tmp->start << PAGE_SHIFT;
+	r = amdgpu_ttm_gart_bind(adev, bo, flags);
+	if (unlikely(r)) {
+		ttm_resource_free(bo, &tmp);
+		return r;
 	}
 
+	ttm_resource_free(bo, &bo->resource);
+	ttm_bo_assign_mem(bo, tmp);
+
 	return 0;
 }
 
diff --git a/drivers/gpu/drm/nouveau/nouveau_bo.c b/drivers/gpu/drm/nouveau/nouveau_bo.c
index e688ca77483d..3a0d9b3bf991 100644
--- a/drivers/gpu/drm/nouveau/nouveau_bo.c
+++ b/drivers/gpu/drm/nouveau/nouveau_bo.c
@@ -1009,7 +1009,7 @@ nouveau_bo_move(struct ttm_buffer_object *bo, bool evict,
 	if (old_reg->mem_type == TTM_PL_TT &&
 	    new_reg->mem_type == TTM_PL_SYSTEM) {
 		nouveau_ttm_tt_unbind(bo->bdev, bo->ttm);
-		ttm_resource_free(bo, bo->resource);
+		ttm_resource_free(bo, &bo->resource);
 		ttm_bo_assign_mem(bo, new_reg);
 		goto out;
 	}
diff --git a/drivers/gpu/drm/radeon/radeon_ttm.c b/drivers/gpu/drm/radeon/radeon_ttm.c
index 2507c1741681..cdffa9b65108 100644
--- a/drivers/gpu/drm/radeon/radeon_ttm.c
+++ b/drivers/gpu/drm/radeon/radeon_ttm.c
@@ -229,7 +229,7 @@ static int radeon_bo_move(struct ttm_buffer_object *bo, bool evict,
 	if (old_mem->mem_type == TTM_PL_TT &&
 	    new_mem->mem_type == TTM_PL_SYSTEM) {
 		radeon_ttm_tt_unbind(bo->bdev, bo->ttm);
-		ttm_resource_free(bo, bo->resource);
+		ttm_resource_free(bo, &bo->resource);
 		ttm_bo_assign_mem(bo, new_mem);
 		goto out;
 	}
diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c
index 5a7ab4b35b2d..4ed56520b81d 100644
--- a/drivers/gpu/drm/ttm/ttm_bo.c
+++ b/drivers/gpu/drm/ttm/ttm_bo.c
@@ -223,7 +223,7 @@ static void ttm_bo_cleanup_memtype_use(struct ttm_buffer_object *bo)
 		bo->bdev->funcs->delete_mem_notify(bo);
 
 	ttm_bo_tt_destroy(bo);
-	ttm_resource_free(bo, bo->resource);
+	ttm_resource_free(bo, &bo->resource);
 }
 
 static int ttm_bo_individualize_resv(struct ttm_buffer_object *bo)
@@ -489,7 +489,7 @@ static int ttm_bo_evict(struct ttm_buffer_object *bo,
 			struct ttm_operation_ctx *ctx)
 {
 	struct ttm_device *bdev = bo->bdev;
-	struct ttm_resource evict_mem;
+	struct ttm_resource *evict_mem;
 	struct ttm_placement placement;
 	struct ttm_place hop;
 	int ret = 0;
@@ -519,7 +519,7 @@ static int ttm_bo_evict(struct ttm_buffer_object *bo,
 		goto out;
 	}
 
-	ret = ttm_bo_handle_move_mem(bo, &evict_mem, true, ctx, &hop);
+	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)
@@ -728,14 +728,15 @@ static int ttm_bo_add_move_fence(struct ttm_buffer_object *bo,
  */
 static int ttm_bo_mem_force_space(struct ttm_buffer_object *bo,
 				  const struct ttm_place *place,
-				  struct ttm_resource *mem,
+				  struct ttm_resource **mem,
 				  struct ttm_operation_ctx *ctx)
 {
 	struct ttm_device *bdev = bo->bdev;
-	struct ttm_resource_manager *man = ttm_manager_type(bdev, mem->mem_type);
+	struct ttm_resource_manager *man;
 	struct ww_acquire_ctx *ticket;
 	int ret;
 
+	man = ttm_manager_type(bdev, (*mem)->mem_type);
 	ticket = dma_resv_locking_ctx(bo->base.resv);
 	do {
 		ret = ttm_resource_alloc(bo, place, mem);
@@ -749,37 +750,7 @@ static int ttm_bo_mem_force_space(struct ttm_buffer_object *bo,
 			return ret;
 	} while (1);
 
-	return ttm_bo_add_move_fence(bo, man, mem, ctx->no_wait_gpu);
-}
-
-/**
- * ttm_bo_mem_placement - check if placement is compatible
- * @bo: BO to find memory for
- * @place: where to search
- * @mem: the memory object to fill in
- *
- * Check if placement is compatible and fill in mem structure.
- * Returns -EBUSY if placement won't work or negative error code.
- * 0 when placement can be used.
- */
-static int ttm_bo_mem_placement(struct ttm_buffer_object *bo,
-				const struct ttm_place *place,
-				struct ttm_resource *mem)
-{
-	struct ttm_device *bdev = bo->bdev;
-	struct ttm_resource_manager *man;
-
-	man = ttm_manager_type(bdev, place->mem_type);
-	if (!man || !ttm_resource_manager_used(man))
-		return -EBUSY;
-
-	mem->mem_type = place->mem_type;
-	mem->placement = place->flags;
-
-	spin_lock(&bo->bdev->lru_lock);
-	ttm_bo_move_to_lru_tail(bo, mem, NULL);
-	spin_unlock(&bo->bdev->lru_lock);
-	return 0;
+	return ttm_bo_add_move_fence(bo, man, *mem, ctx->no_wait_gpu);
 }
 
 /*
@@ -792,7 +763,7 @@ static int ttm_bo_mem_placement(struct ttm_buffer_object *bo,
  */
 int ttm_bo_mem_space(struct ttm_buffer_object *bo,
 			struct ttm_placement *placement,
-			struct ttm_resource *mem,
+			struct ttm_resource **mem,
 			struct ttm_operation_ctx *ctx)
 {
 	struct ttm_device *bdev = bo->bdev;
@@ -807,8 +778,8 @@ int ttm_bo_mem_space(struct ttm_buffer_object *bo,
 		const struct ttm_place *place = &placement->placement[i];
 		struct ttm_resource_manager *man;
 
-		ret = ttm_bo_mem_placement(bo, place, mem);
-		if (ret)
+		man = ttm_manager_type(bdev, place->mem_type);
+		if (!man || !ttm_resource_manager_used(man))
 			continue;
 
 		type_found = true;
@@ -818,8 +789,7 @@ int ttm_bo_mem_space(struct ttm_buffer_object *bo,
 		if (unlikely(ret))
 			goto error;
 
-		man = ttm_manager_type(bdev, mem->mem_type);
-		ret = ttm_bo_add_move_fence(bo, man, mem, ctx->no_wait_gpu);
+		ret = ttm_bo_add_move_fence(bo, man, *mem, ctx->no_wait_gpu);
 		if (unlikely(ret)) {
 			ttm_resource_free(bo, mem);
 			if (ret == -EBUSY)
@@ -832,9 +802,10 @@ int ttm_bo_mem_space(struct ttm_buffer_object *bo,
 
 	for (i = 0; i < placement->num_busy_placement; ++i) {
 		const struct ttm_place *place = &placement->busy_placement[i];
+		struct ttm_resource_manager *man;
 
-		ret = ttm_bo_mem_placement(bo, place, mem);
-		if (ret)
+		man = ttm_manager_type(bdev, place->mem_type);
+		if (!man || !ttm_resource_manager_used(man))
 			continue;
 
 		type_found = true;
@@ -861,12 +832,12 @@ error:
 EXPORT_SYMBOL(ttm_bo_mem_space);
 
 static int ttm_bo_bounce_temp_buffer(struct ttm_buffer_object *bo,
-				     struct ttm_resource *mem,
+				     struct ttm_resource **mem,
 				     struct ttm_operation_ctx *ctx,
 				     struct ttm_place *hop)
 {
 	struct ttm_placement hop_placement;
-	struct ttm_resource hop_mem;
+	struct ttm_resource *hop_mem;
 	int ret;
 
 	hop_placement.num_placement = hop_placement.num_busy_placement = 1;
@@ -877,7 +848,7 @@ static int ttm_bo_bounce_temp_buffer(struct ttm_buffer_object *bo,
 	if (ret)
 		return ret;
 	/* move to the bounce domain */
-	ret = ttm_bo_handle_move_mem(bo, &hop_mem, false, ctx, NULL);
+	ret = ttm_bo_handle_move_mem(bo, hop_mem, false, ctx, NULL);
 	if (ret) {
 		ttm_resource_free(bo, &hop_mem);
 		return ret;
@@ -889,14 +860,12 @@ static int ttm_bo_move_buffer(struct ttm_buffer_object *bo,
 			      struct ttm_placement *placement,
 			      struct ttm_operation_ctx *ctx)
 {
+	struct ttm_resource *mem;
 	struct ttm_place hop;
-	struct ttm_resource mem;
 	int ret;
 
 	dma_resv_assert_held(bo->base.resv);
 
-	memset(&hop, 0, sizeof(hop));
-
 	/*
 	 * Determine where to move the buffer.
 	 *
@@ -910,7 +879,7 @@ static int ttm_bo_move_buffer(struct ttm_buffer_object *bo,
 	if (ret)
 		return ret;
 bounce:
-	ret = ttm_bo_handle_move_mem(bo, &mem, false, ctx, &hop);
+	ret = ttm_bo_handle_move_mem(bo, mem, false, ctx, &hop);
 	if (ret == -EMULTIHOP) {
 		ret = ttm_bo_bounce_temp_buffer(bo, &mem, ctx, &hop);
 		if (ret)
@@ -1019,7 +988,7 @@ int ttm_bo_init_reserved(struct ttm_device *bdev,
 {
 	static const struct ttm_place sys_mem = { .mem_type = TTM_PL_SYSTEM };
 	bool locked;
-	int ret = 0;
+	int ret;
 
 	bo->destroy = destroy ? destroy : ttm_bo_default_destroy;
 
@@ -1029,8 +998,6 @@ int ttm_bo_init_reserved(struct ttm_device *bdev,
 	bo->bdev = bdev;
 	bo->type = type;
 	bo->page_alignment = page_alignment;
-	bo->resource = &bo->_mem;
-	ttm_resource_alloc(bo, &sys_mem, bo->resource);
 	bo->moving = NULL;
 	bo->pin_count = 0;
 	bo->sg = sg;
@@ -1042,6 +1009,12 @@ int ttm_bo_init_reserved(struct ttm_device *bdev,
 	}
 	atomic_inc(&ttm_glob.bo_count);
 
+	ret = ttm_resource_alloc(bo, &sys_mem, &bo->resource);
+	if (unlikely(ret)) {
+		ttm_bo_put(bo);
+		return ret;
+	}
+
 	/*
 	 * For ttm_bo_type_device buffers, allocate
 	 * address space from the device.
@@ -1170,7 +1143,7 @@ int ttm_bo_swapout(struct ttm_buffer_object *bo, struct ttm_operation_ctx *ctx,
 	 */
 	if (bo->resource->mem_type != TTM_PL_SYSTEM) {
 		struct ttm_operation_ctx ctx = { false, false };
-		struct ttm_resource evict_mem;
+		struct ttm_resource *evict_mem;
 		struct ttm_place place, hop;
 
 		memset(&place, 0, sizeof(place));
@@ -1182,7 +1155,7 @@ int ttm_bo_swapout(struct ttm_buffer_object *bo, struct ttm_operation_ctx *ctx,
 		if (unlikely(ret))
 			goto out;
 
-		ret = ttm_bo_handle_move_mem(bo, &evict_mem, true, &ctx, &hop);
+		ret = ttm_bo_handle_move_mem(bo, evict_mem, true, &ctx, &hop);
 		if (unlikely(ret != 0)) {
 			WARN(ret == -EMULTIHOP, "Unexpected multihop in swaput - likely driver bug.\n");
 			goto out;
diff --git a/drivers/gpu/drm/ttm/ttm_bo_util.c b/drivers/gpu/drm/ttm/ttm_bo_util.c
index aedf02a31c70..1b326e70cb02 100644
--- a/drivers/gpu/drm/ttm/ttm_bo_util.c
+++ b/drivers/gpu/drm/ttm/ttm_bo_util.c
@@ -176,16 +176,17 @@ int ttm_bo_move_memcpy(struct ttm_buffer_object *bo,
 		       struct ttm_operation_ctx *ctx,
 		       struct ttm_resource *new_mem)
 {
+	struct ttm_resource *old_mem = bo->resource;
 	struct ttm_device *bdev = bo->bdev;
-	struct ttm_resource_manager *man = ttm_manager_type(bdev, new_mem->mem_type);
+	struct ttm_resource_manager *man;
 	struct ttm_tt *ttm = bo->ttm;
-	struct ttm_resource *old_mem = bo->resource;
-	struct ttm_resource old_copy = *old_mem;
 	void *old_iomap;
 	void *new_iomap;
 	int ret;
 	unsigned long i;
 
+	man = ttm_manager_type(bdev, new_mem->mem_type);
+
 	ret = ttm_bo_wait_ctx(bo, ctx);
 	if (ret)
 		return ret;
@@ -201,7 +202,7 @@ int ttm_bo_move_memcpy(struct ttm_buffer_object *bo,
 	 * Single TTM move. NOP.
 	 */
 	if (old_iomap == NULL && new_iomap == NULL)
-		goto out2;
+		goto out1;
 
 	/*
 	 * Don't move nonexistent data. Clear destination instead.
@@ -210,7 +211,7 @@ int ttm_bo_move_memcpy(struct ttm_buffer_object *bo,
 	    (ttm == NULL || (!ttm_tt_is_populated(ttm) &&
 			     !(ttm->page_flags & TTM_PAGE_FLAG_SWAPPED)))) {
 		memset_io(new_iomap, 0, new_mem->num_pages*PAGE_SIZE);
-		goto out2;
+		goto out1;
 	}
 
 	/*
@@ -235,27 +236,25 @@ int ttm_bo_move_memcpy(struct ttm_buffer_object *bo,
 			ret = ttm_copy_io_page(new_iomap, old_iomap, i);
 		}
 		if (ret)
-			goto out1;
+			break;
 	}
 	mb();
-out2:
-	old_copy = *old_mem;
+out1:
+	ttm_resource_iounmap(bdev, new_mem, new_iomap);
+out:
+	ttm_resource_iounmap(bdev, old_mem, old_iomap);
+
+	if (ret) {
+		ttm_resource_free(bo, &new_mem);
+		return ret;
+	}
 
+	ttm_resource_free(bo, &bo->resource);
 	ttm_bo_assign_mem(bo, new_mem);
 
 	if (!man->use_tt)
 		ttm_bo_tt_destroy(bo);
 
-out1:
-	ttm_resource_iounmap(bdev, old_mem, new_iomap);
-out:
-	ttm_resource_iounmap(bdev, &old_copy, old_iomap);
-
-	/*
-	 * On error, keep the mm node!
-	 */
-	if (!ret)
-		ttm_resource_free(bo, &old_copy);
 	return ret;
 }
 EXPORT_SYMBOL(ttm_bo_move_memcpy);
@@ -566,7 +565,7 @@ static int ttm_bo_wait_free_node(struct ttm_buffer_object *bo,
 
 	if (!dst_use_tt)
 		ttm_bo_tt_destroy(bo);
-	ttm_resource_free(bo, bo->resource);
+	ttm_resource_free(bo, &bo->resource);
 	return 0;
 }
 
@@ -629,7 +628,7 @@ static void ttm_bo_move_pipeline_evict(struct ttm_buffer_object *bo,
 	}
 	spin_unlock(&from->move_lock);
 
-	ttm_resource_free(bo, bo->resource);
+	ttm_resource_free(bo, &bo->resource);
 
 	dma_fence_put(bo->moving);
 	bo->moving = dma_fence_get(fence);
@@ -678,11 +677,11 @@ int ttm_bo_pipeline_gutting(struct ttm_buffer_object *bo)
 	if (ret)
 		ttm_bo_wait(bo, false, false);
 
-	ttm_resource_alloc(bo, &sys_mem, bo->resource);
+	ret = ttm_resource_alloc(bo, &sys_mem, &bo->resource);
 	bo->ttm = NULL;
 
 	dma_resv_unlock(&ghost->base._resv);
 	ttm_bo_put(ghost);
 
-	return 0;
+	return ret;
 }
diff --git a/drivers/gpu/drm/ttm/ttm_resource.c b/drivers/gpu/drm/ttm/ttm_resource.c
index 59e2b7157e41..65451e1bc303 100644
--- a/drivers/gpu/drm/ttm/ttm_resource.c
+++ b/drivers/gpu/drm/ttm/ttm_resource.c
@@ -27,10 +27,16 @@
 
 int ttm_resource_alloc(struct ttm_buffer_object *bo,
 		       const struct ttm_place *place,
-		       struct ttm_resource *res)
+		       struct ttm_resource **res_ptr)
 {
 	struct ttm_resource_manager *man =
 		ttm_manager_type(bo->bdev, place->mem_type);
+	struct ttm_resource *res;
+	int r;
+
+	res = kmalloc(sizeof(*res), GFP_KERNEL);
+	if (!res)
+		return -ENOMEM;
 
 	res->mm_node = NULL;
 	res->start = 0;
@@ -41,18 +47,27 @@ int ttm_resource_alloc(struct ttm_buffer_object *bo,
 	res->bus.offset = 0;
 	res->bus.is_iomem = false;
 	res->bus.caching = ttm_cached;
+	r = man->func->alloc(man, bo, place, res);
+	if (r) {
+		kfree(res);
+		return r;
+	}
 
-	return man->func->alloc(man, bo, place, res);
+	*res_ptr = res;
+	return 0;
 }
 
-void ttm_resource_free(struct ttm_buffer_object *bo, struct ttm_resource *res)
+void ttm_resource_free(struct ttm_buffer_object *bo, struct ttm_resource **res)
 {
-	struct ttm_resource_manager *man =
-		ttm_manager_type(bo->bdev, res->mem_type);
+	struct ttm_resource_manager *man;
 
-	man->func->free(man, res);
-	res->mm_node = NULL;
-	res->mem_type = TTM_PL_SYSTEM;
+	if (!*res)
+		return;
+
+	man = ttm_manager_type(bo->bdev, (*res)->mem_type);
+	man->func->free(man, *res);
+	kfree(*res);
+	*res = NULL;
 }
 EXPORT_SYMBOL(ttm_resource_free);
 
diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_ttm_buffer.c b/drivers/gpu/drm/vmwgfx/vmwgfx_ttm_buffer.c
index ed8563ef9a3b..bfcf31bf7e37 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_ttm_buffer.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_ttm_buffer.c
@@ -741,7 +741,7 @@ static int vmw_move(struct ttm_buffer_object *bo,
 			goto fail;
 
 		vmw_ttm_unbind(bo->bdev, bo->ttm);
-		ttm_resource_free(bo, bo->resource);
+		ttm_resource_free(bo, &bo->resource);
 		ttm_bo_assign_mem(bo, new_mem);
 		return 0;
 	} else {
diff --git a/include/drm/ttm/ttm_bo_api.h b/include/drm/ttm/ttm_bo_api.h
index 291a339a7e08..f681bbdbc698 100644
--- a/include/drm/ttm/ttm_bo_api.h
+++ b/include/drm/ttm/ttm_bo_api.h
@@ -137,7 +137,6 @@ struct ttm_buffer_object {
 	 */
 
 	struct ttm_resource *resource;
-	struct ttm_resource _mem;
 	struct ttm_tt *ttm;
 	bool deleted;
 
diff --git a/include/drm/ttm/ttm_bo_driver.h b/include/drm/ttm/ttm_bo_driver.h
index 1a9ba0b13622..ead0ef7136c8 100644
--- a/include/drm/ttm/ttm_bo_driver.h
+++ b/include/drm/ttm/ttm_bo_driver.h
@@ -96,7 +96,7 @@ struct ttm_lru_bulk_move {
  */
 int ttm_bo_mem_space(struct ttm_buffer_object *bo,
 		     struct ttm_placement *placement,
-		     struct ttm_resource *mem,
+		     struct ttm_resource **mem,
 		     struct ttm_operation_ctx *ctx);
 
 /**
@@ -188,8 +188,8 @@ ttm_bo_move_to_lru_tail_unlocked(struct ttm_buffer_object *bo)
 static inline void ttm_bo_assign_mem(struct ttm_buffer_object *bo,
 				     struct ttm_resource *new_mem)
 {
-	bo->_mem = *new_mem;
-	new_mem->mm_node = NULL;
+	WARN_ON(bo->resource);
+	bo->resource = new_mem;
 }
 
 /**
@@ -202,9 +202,7 @@ static inline void ttm_bo_assign_mem(struct ttm_buffer_object *bo,
 static inline void ttm_bo_move_null(struct ttm_buffer_object *bo,
 				    struct ttm_resource *new_mem)
 {
-	struct ttm_resource *old_mem = bo->resource;
-
-	WARN_ON(old_mem->mm_node != NULL);
+	ttm_resource_free(bo, &bo->resource);
 	ttm_bo_assign_mem(bo, new_mem);
 }
 
diff --git a/include/drm/ttm/ttm_resource.h b/include/drm/ttm/ttm_resource.h
index 890b9d369519..c17c1a52070d 100644
--- a/include/drm/ttm/ttm_resource.h
+++ b/include/drm/ttm/ttm_resource.h
@@ -225,8 +225,8 @@ ttm_resource_manager_cleanup(struct ttm_resource_manager *man)
 
 int ttm_resource_alloc(struct ttm_buffer_object *bo,
 		       const struct ttm_place *place,
-		       struct ttm_resource *res);
-void ttm_resource_free(struct ttm_buffer_object *bo, struct ttm_resource *res);
+		       struct ttm_resource **res);
+void ttm_resource_free(struct ttm_buffer_object *bo, struct ttm_resource **res);
 
 void ttm_resource_manager_init(struct ttm_resource_manager *man,
 			       unsigned long p_size);