Re: [PATCH v3 3/3] drm/gpusvm: publish dpagemap early to avoid device mapping leak on error

[Matthew Brost <matthew.brost@intel.com>]

On Tue, Jun 30, 2026 at 03:08:59PM +0800, Honglei Huang wrote:
> drm_gpusvm_get_pages() only stored the local dpagemap into
> svm_pages->dpagemap on the success path. If a later page failed (e.g.
> -EOPNOTSUPP when ctx->allow_mixed is false) and jumped to err_unmap,
> svm_pages->dpagemap was still NULL, so __drm_gpusvm_unmap_pages() skipped
> device_unmap() and leaked the device mappings already created.
> 
> Assign svm_pages->dpagemap when the first device page is mapped so the
> err_unmap path can device_unmap() those mappings.
> 
> This issue was found by Sashiko AI review.
> 
> Fixes: f70da6f99d4f ("drm/gpusvm: pull out drm_gpusvm_pages substructure")
> Cc: stable@vger.kernel.org

Reviewed-by: Matthew Brost <matthew.brost@intel.com>

> Signed-off-by: Honglei Huang <honghuan@amd.com>
> ---
>  drivers/gpu/drm/drm_gpusvm.c | 16 +++++++++++-----
>  1 file changed, 11 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_gpusvm.c b/drivers/gpu/drm/drm_gpusvm.c
> index 44bb19658dd..9a06ff7d260 100644
> --- a/drivers/gpu/drm/drm_gpusvm.c
> +++ b/drivers/gpu/drm/drm_gpusvm.c
> @@ -1544,6 +1544,16 @@ int drm_gpusvm_get_pages(struct drm_gpusvm *gpusvm,
>  					err = -EAGAIN;
>  					goto err_unmap;
>  				}
> +
> +				/*
> +				 * Set the dpagemap as soon as the first
> +				 * device page is mapped so the err_unmap path
> +				 * can device_unmap() the device mappings that
> +				 * have already been created.
> +				 */
> +				drm_pagemap_get(dpagemap);
> +				drm_pagemap_put(svm_pages->dpagemap);
> +				svm_pages->dpagemap = dpagemap;
>  			}
>  			svm_pages->dma_addr[j] =
>  				dpagemap->ops->device_map(dpagemap,
> @@ -1611,12 +1621,8 @@ int drm_gpusvm_get_pages(struct drm_gpusvm *gpusvm,
>  			goto err_unmap;
>  	}
>  
> -	if (pagemap) {
> +	if (pagemap)
>  		flags.has_devmem_pages = true;
> -		drm_pagemap_get(dpagemap);
> -		drm_pagemap_put(svm_pages->dpagemap);
> -		svm_pages->dpagemap = dpagemap;
> -	}
>  
>  	/* WRITE_ONCE pairs with READ_ONCE for opportunistic checks */
>  	WRITE_ONCE(svm_pages->flags.__flags, flags.__flags);
> -- 
> 2.34.1
>