Re: [PATCH] drm/amdgpu: Need to set moved to true when evict bo

["Zhang, Jerry (Junwei)" <Jerry.Zhang-5C7GfCeVMHo@public.gmane.org>]

On 08/28/2018 08:40 PM, Emily Deng wrote:
> Fix the VMC page fault when the running sequence is as below:
> 1.amdgpu_gem_create_ioctl
> 2.ttm_bo_swapout->amdgpu_vm_bo_invalidate, as not called
> amdgpu_vm_bo_base_init, so won't called
> list_add_tail(&base->bo_list, &bo->va). Even the bo was evicted,
> it won't set the bo_base->moved.

IMO, the evicted bo should be created previously.
On BO creation we will add it to the bo->va as below:

amdgpu_gem_create_ioctl
   drm_gem_handle_create
     amdgpu_gem_object_open
       amdgpu_vm_bo_add
         amdgpu_vm_bo_base_init
           list_add_tail(&base->bo_list, &bo->va)

Then it could be set moved in bo invalidate when evicting.

could you provide a bit more backgroud about the issue?
looks a per vm bo is evicted and a new same bo created.

Jerry

> 3.drm_gem_open_ioctl->amdgpu_vm_bo_base_init, here only called
> list_move_tail(&base->vm_status, &vm->evicted), but not set the
> bo_base->moved.
> 4.amdgpu_vm_bo_map->amdgpu_vm_bo_insert_map, as the bo_base->moved is
> not set true, the function amdgpu_vm_bo_insert_map will call
> list_move(&bo_va->base.vm_status, &vm->moved)
> 5.amdgpu_cs_ioctl won't validate the swapout bo, as it is only in the
> moved list, not in the evict list. So VMC page fault occurs.
>
> Signed-off-by: Emily Deng <Emily.Deng@amd.com>
> ---
>   drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c | 1 +
>   1 file changed, 1 insertion(+)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
> index 1f4b8df..015e20e 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
> @@ -172,6 +172,7 @@ static void amdgpu_vm_bo_base_init(struct amdgpu_vm_bo_base *base,
>   	 * is validated on next vm use to avoid fault.
>   	 * */
>   	list_move_tail(&base->vm_status, &vm->evicted);
> +	base->moved = true;
>   }
>
>   /**
>
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