Re: [RESEND RFC PATCH v3 3/6] drm/amdgpu: Handle GPU page faults correctly on non-4K page systems

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

On 3/23/26 05:28, Donet Tom wrote:
> During a GPU page fault, the driver restores the SVM range and then maps it
> into the GPU page tables. The current implementation passes a GPU-page-size
> (4K-based) PFN to svm_range_restore_pages() to restore the range.
> 
> SVM ranges are tracked using system-page-size PFNs. On systems where the
> system page size is larger than 4K, using GPU-page-size PFNs to restore the
> range causes two problems:
> 
> Range lookup fails:
> Because the restore function receives PFNs in GPU (4K) units, the SVM
> range lookup does not find the existing range. This will result in a
> duplicate SVM range being created.
> 
> VMA lookup failure:
> The restore function also tries to locate the VMA for the faulting address.
> It converts the GPU-page-size PFN into an address using the system page
> size, which results in an incorrect address on non-4K page-size systems.
> As a result, the VMA lookup fails with the message: "address 0xxxx VMA is
> removed".
> 
> This patch passes the system-page-size PFN to svm_range_restore_pages() so
> that the SVM range is restored correctly on non-4K page systems.
> 
> Signed-off-by: Donet Tom <donettom@linux.ibm.com>

Acked-by: Christian König <christian.koenig@amd.com>

> ---
>  drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
> index 6a2ea200d90c..7a3cb0057ac5 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
> @@ -2985,14 +2985,14 @@ bool amdgpu_vm_handle_fault(struct amdgpu_device *adev, u32 pasid,
>  	if (!root)
>  		return false;
>  
> -	addr /= AMDGPU_GPU_PAGE_SIZE;
> -
>  	if (is_compute_context && !svm_range_restore_pages(adev, pasid, vmid,
> -	    node_id, addr, ts, write_fault)) {
> +	    node_id, addr >> PAGE_SHIFT, ts, write_fault)) {
>  		amdgpu_bo_unref(&root);
>  		return true;
>  	}
>  
> +	addr /= AMDGPU_GPU_PAGE_SIZE;
> +
>  	r = amdgpu_bo_reserve(root, true);
>  	if (r)
>  		goto error_unref;