[PATCH] drm/amdgpu: fix max_entries calculation v2

[Pan, Xinhui]

> 2020年9月2日 22:05，Christian König <ckoenig.leichtzumerken at gmail.com> 写道：
> 
> Calculate the correct value for max_entries or we might run after the
> page_address array.
> 
> v2: Xinhui pointed out we don't need the shift
> 
> Signed-off-by: Christian König <christian.koenig at amd.com>
> Fixes: 1e691e244487 drm/amdgpu: stop allocating dummy GTT nodes
> ---
> drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
> index 8bc2253939be..be886bdca5c6 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
> @@ -1697,7 +1697,7 @@ static int amdgpu_vm_bo_split_mapping(struct amdgpu_device *adev,
> 				AMDGPU_GPU_PAGES_IN_CPU_PAGE;
> 		} else {
> 			addr = 0;
> -			max_entries = S64_MAX;
> +			max_entries = mapping->last - mapping->start + 1;

You need minus pfn here.

The range we are going to touch is [start + offset, last].
so the max_entries is last - (start + offset) + 1. and offset is pfn in this case.

I still hit panic with this patch in practice.

> 		}
> 
> 		if (pages_addr) {
> -- 
> 2.17.1
>