Re: [PATCH] drm/ttm: fix missing NULL check in ttm_device_swapout

[Felix Kuehling <felix.kuehling@amd.com>]

On 2022-06-03 06:46, Christian König wrote:
> Resources about to be destructed are not tied to BOs any more.
I've been seeing a backtrace in that area with a patch series I'm 
working on, but didn't have enough time to track it down yet. I'll try 
if this patch fixes it.

Regards,
   Felix


>
> Signed-off-by: Christian König <christian.koenig@amd.com>
> ---
>   drivers/gpu/drm/ttm/ttm_device.c | 6 +++++-
>   1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/ttm/ttm_device.c b/drivers/gpu/drm/ttm/ttm_device.c
> index a0562ab386f5..e7147e304637 100644
> --- a/drivers/gpu/drm/ttm/ttm_device.c
> +++ b/drivers/gpu/drm/ttm/ttm_device.c
> @@ -156,8 +156,12 @@ int ttm_device_swapout(struct ttm_device *bdev, struct ttm_operation_ctx *ctx,
>   
>   		ttm_resource_manager_for_each_res(man, &cursor, res) {
>   			struct ttm_buffer_object *bo = res->bo;
> -			uint32_t num_pages = PFN_UP(bo->base.size);
> +			uint32_t num_pages;
>   
> +			if (!bo)
> +				continue;
> +
> +			num_pages = PFN_UP(bo->base.size);
>   			ret = ttm_bo_swapout(bo, ctx, gfp_flags);
>   			/* ttm_bo_swapout has dropped the lru_lock */
>   			if (!ret)