Re: [PATCH v6 09/11] drm/amdgpu: validate the shared bo for tracking usage size

["Christian König" <christian.koenig@amd.com>]

On 11.07.25 11:39, Prike Liang wrote:
> It requires validating the shared BO before updating its usage
> size; otherwise, there is a potential NULL pointer error when the
> BO released improperly.

Clear NAK to that. You are obviously working around a bug elsewhere.

Regards,
Christian.

> 
> Signed-off-by: Prike Liang <Prike.Liang@amd.com>
> ---
>  drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c | 25 +++++++++++++++++++++----
>  1 file changed, 21 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
> index f042372d9f2e..a574effdd3ec 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
> @@ -321,12 +321,26 @@ static void amdgpu_vm_bo_reset_state_machine(struct amdgpu_vm *vm)
>   */
>  static void amdgpu_vm_update_shared(struct amdgpu_vm_bo_base *base)
>  {
> -	struct amdgpu_vm *vm = base->vm;
> -	struct amdgpu_bo *bo = base->bo;
> -	uint64_t size = amdgpu_bo_size(bo);
> -	uint32_t bo_memtype = amdgpu_bo_mem_stats_placement(bo);
> +	struct amdgpu_vm *vm;
> +	struct amdgpu_bo *bo;
> +	uint64_t size = 0;
> +	uint32_t bo_memtype = TTM_PL_SYSTEM;
>  	bool shared;
>  
> +	if (likely(base)) {
> +		vm = base->vm;
> +		bo = base->bo;
> +	} else {
> +		return;
> +	}
> +
> +	if (likely(bo)) {
> +		size = amdgpu_bo_size(bo);
> +		bo_memtype = amdgpu_bo_mem_stats_placement(bo);
> +	} else {
> +		return;
> +	}
> +
>  	spin_lock(&vm->status_lock);
>  	shared = drm_gem_object_is_shared_for_memory_stats(&bo->tbo.base);
>  	if (base->shared != shared) {
> @@ -353,6 +367,9 @@ void amdgpu_vm_bo_update_shared(struct amdgpu_bo *bo)
>  {
>  	struct amdgpu_vm_bo_base *base;
>  
> +	if (unlikely(!bo))
> +		return;
> +
>  	for (base = bo->vm_bo; base; base = base->next)
>  		amdgpu_vm_update_shared(base);
>  }