diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
index 924c19ce3f5a..fc5f7ac53d0a 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
@@ -751,6 +751,7 @@ static int amdgpu_ttm_io_mem_reserve(struct ttm_bo_device *bdev, struct ttm_reso
 {
 	struct amdgpu_device *adev = amdgpu_ttm_adev(bdev);
 	struct drm_mm_node *mm_node = mem->mm_node;
+	size_t bus_size = (size_t)mem->num_pages << PAGE_SHIFT;
 
 	switch (mem->mem_type) {
 	case TTM_PL_SYSTEM:
@@ -761,7 +762,7 @@ static int amdgpu_ttm_io_mem_reserve(struct ttm_bo_device *bdev, struct ttm_reso
 	case TTM_PL_VRAM:
 		mem->bus.offset = mem->start << PAGE_SHIFT;
 		/* check if it's visible */
-		if ((mem->bus.offset + mem->bus.size) > adev->gmc.visible_vram_size)
+		if ((mem->bus.offset + bus_size) > adev->gmc.visible_vram_size)
 			return -EINVAL;
 		/* Only physically contiguous buffers apply. In a contiguous
 		 * buffer, size of the first mm_node would match the number of
diff --git a/drivers/gpu/drm/radeon/radeon_ttm.c b/drivers/gpu/drm/radeon/radeon_ttm.c
index 8ca2253f6fbf..3a4372ea74b9 100644
--- a/drivers/gpu/drm/radeon/radeon_ttm.c
+++ b/drivers/gpu/drm/radeon/radeon_ttm.c
@@ -362,6 +362,7 @@ memcpy:
 static int radeon_ttm_io_mem_reserve(struct ttm_bo_device *bdev, struct ttm_resource *mem)
 {
 	struct radeon_device *rdev = radeon_get_rdev(bdev);
+	size_t bus_size = (size_t)mem->num_pages << PAGE_SHIFT;
 
 	switch (mem->mem_type) {
 	case TTM_PL_SYSTEM:
@@ -380,7 +381,7 @@ static int radeon_ttm_io_mem_reserve(struct ttm_bo_device *bdev, struct ttm_reso
 	case TTM_PL_VRAM:
 		mem->bus.offset = mem->start << PAGE_SHIFT;
 		/* check if it's visible */
-		if ((mem->bus.offset + mem->bus.size) > rdev->mc.visible_vram_size)
+		if ((mem->bus.offset + bus_size) > rdev->mc.visible_vram_size)
 			return -EINVAL;
 		mem->bus.base = rdev->mc.aper_base;
 		mem->bus.is_iomem = true;
@@ -392,11 +393,11 @@ static int radeon_ttm_io_mem_reserve(struct ttm_bo_device *bdev, struct ttm_reso
 		if (mem->placement & TTM_PL_FLAG_WC)
 			mem->bus.addr =
 				ioremap_wc(mem->bus.base + mem->bus.offset,
-					   mem->bus.size);
+					   bus_size);
 		else
 			mem->bus.addr =
 				ioremap(mem->bus.base + mem->bus.offset,
-						mem->bus.size);
+					bus_size);
 		if (!mem->bus.addr)
 			return -ENOMEM;
 
diff --git a/drivers/gpu/drm/ttm/ttm_bo_util.c b/drivers/gpu/drm/ttm/ttm_bo_util.c
index eaed29b81d9e..ee04716b2603 100644
--- a/drivers/gpu/drm/ttm/ttm_bo_util.c
+++ b/drivers/gpu/drm/ttm/ttm_bo_util.c
@@ -140,7 +140,6 @@ int ttm_mem_io_reserve(struct ttm_bo_device *bdev,
 
 	mem->bus.addr = NULL;
 	mem->bus.offset = 0;
-	mem->bus.size = mem->num_pages << PAGE_SHIFT;
 	mem->bus.base = 0;
 	mem->bus.is_iomem = false;
 retry:
@@ -214,12 +213,14 @@ static int ttm_resource_ioremap(struct ttm_bo_device *bdev,
 	if (mem->bus.addr) {
 		addr = mem->bus.addr;
 	} else {
+		size_t bus_size = (size_t)mem->num_pages << PAGE_SHIFT;
+
 		if (mem->placement & TTM_PL_FLAG_WC)
 			addr = ioremap_wc(mem->bus.base + mem->bus.offset,
-					  mem->bus.size);
+					  bus_size);
 		else
 			addr = ioremap(mem->bus.base + mem->bus.offset,
-				       mem->bus.size);
+				       bus_size);
 		if (!addr) {
 			(void) ttm_mem_io_lock(man, false);
 			ttm_mem_io_free(bdev, mem);
diff --git a/include/drm/ttm/ttm_resource.h b/include/drm/ttm/ttm_resource.h
index bac22a56f6cd..6d4226190480 100644
--- a/include/drm/ttm/ttm_resource.h
+++ b/include/drm/ttm/ttm_resource.h
@@ -162,7 +162,6 @@ struct ttm_resource_manager {
  * @addr:		mapped virtual address
  * @base:		bus base address
  * @is_iomem:		is this io memory ?
- * @size:		size in byte
  * @offset:		offset from the base address
  * @io_reserved_vm:     The VM system has a refcount in @io_reserved_count
  * @io_reserved_count:  Refcounting the numbers of callers to ttm_mem_io_reserve
@@ -172,7 +171,6 @@ struct ttm_resource_manager {
 struct ttm_bus_placement {
 	void		*addr;
 	phys_addr_t	base;
-	unsigned long	size;
 	unsigned long	offset;
 	bool		is_iomem;
 	bool		io_reserved_vm;