Re: [PATCH] drm/amd/amdgpu: Ensure isp_kernel_buffer_alloc() creates a new BO

[Mario Limonciello <mario.limonciello@amd.com>]

On 11/5/25 5:21 PM, Sultan Alsawaf wrote:
> From: Sultan Alsawaf <sultan@kerneltoast.com>
> 
> When the BO pointer provided to amdgpu_bo_create_kernel() points to
> non-NULL, amdgpu_bo_create_kernel() takes it as a hint to pin that address
> rather than allocate a new BO.
> 
> This functionality is never desired for allocating ISP buffers. A new BO
> should always be created when isp_kernel_buffer_alloc() is called, per the
> description for isp_kernel_buffer_alloc().

Are you just going off descriptions, or is there a problem with reuse?

> 
> Ensure this by zeroing *bo right before the amdgpu_bo_create_kernel() call.
> 
> Fixes: 55d42f616976 ("drm/amd/amdgpu: Add helper functions for isp buffers")
> Signed-off-by: Sultan Alsawaf <sultan@kerneltoast.com>
> ---
>   drivers/gpu/drm/amd/amdgpu/amdgpu_isp.c | 2 ++
>   1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_isp.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_isp.c
> index 9cddbf50442a..37270c4dab8d 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_isp.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_isp.c
> @@ -280,6 +280,8 @@ int isp_kernel_buffer_alloc(struct device *dev, u64 size,
>   	if (ret)
>   		return ret;
>   
> +	/* Ensure *bo is NULL so a new BO will be created */
> +	*bo = NULL;
>   	ret = amdgpu_bo_create_kernel(adev,
>   				      size,
>   				      ISP_MC_ADDR_ALIGN,