Re: [PATCH v3 4/6] drm/pagemap: dma-unmap pages before handling migration errors

On 06-08-2026 04:40, Matthew Brost wrote:
> drm_pagemap_migrate_unmap_pages() relies on the pages array to determine
> which pages require DMA unmapping. However,
> drm_pagemap_migration_unlock_put_pages() clears the array as part of its
> cleanup, leaving drm_pagemap_migrate_unmap_pages() with no valid page
> information if it is called afterward.
> 
> Call drm_pagemap_migrate_unmap_pages() before
> drm_pagemap_migration_unlock_put_pages() so the pages array remains
> valid during DMA unmapping.
> 
> Reported-by: Sashiko <[email protected]>
> Fixes: f86ad0ed620c ("drm/gpusvm, drm/pagemap: Move migration functionality to drm_pagemap")
> Cc: Andrew Morton <[email protected]>
> Cc: David Hildenbrand <[email protected]>
> Cc: Lorenzo Stoakes <[email protected]>
> Cc: Zi Yan <[email protected]>
> Cc: Baolin Wang <[email protected]>
> Cc: Liam R. Howlett <[email protected]>
> Cc: Nico Pache <[email protected]>
> Cc: Ryan Roberts <[email protected]>
> Cc: Dev Jain <[email protected]>
> Cc: Barry Song <[email protected]>
> Cc: Lance Yang <[email protected]>
> Cc: Usama Arif <[email protected]>
> Cc: Joshua Hahn <[email protected]>
> Cc: Rakie Kim <[email protected]>
> Cc: Byungchul Park <[email protected]>
> Cc: Gregory Price <[email protected]>
> Cc: Ying Huang <[email protected]>
> Cc: Alistair Popple <[email protected]>
> Cc: Balbir Singh <[email protected]>
> Cc: Maarten Lankhorst <[email protected]>
> Cc: Maxime Ripard <[email protected]>
> Cc: Thomas Zimmermann <[email protected]>
> Cc: David Airlie <[email protected]>
> Cc: Simona Vetter <[email protected]>
> Cc: Thomas Hellström <[email protected]>
> Cc: Francois Dugast <[email protected]>
> Cc: [email protected]
> Cc: [email protected]
> Cc: [email protected]
> Cc: [email protected]
> Signed-off-by: Matthew Brost <[email protected]>
> ---
>   drivers/gpu/drm/drm_pagemap.c | 12 ++++++------
>   1 file changed, 6 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_pagemap.c b/drivers/gpu/drm/drm_pagemap.c
> index 892b325fa99b..aef1fcea663d 100644
> --- a/drivers/gpu/drm/drm_pagemap.c
> +++ b/drivers/gpu/drm/drm_pagemap.c
> @@ -1175,12 +1175,12 @@ int drm_pagemap_evict_to_ram(struct drm_pagemap_devmem *devmem_allocation)
>   		goto err_finalize;
>   
>   err_finalize:
> +	drm_pagemap_migrate_unmap_pages(devmem_allocation->dev, pagemap_addr, dst, npages,
> +					DMA_FROM_DEVICE, &state);
>   	if (err)
>   		drm_pagemap_migration_unlock_put_pages(npages, dst);
>   	migrate_device_pages(src, dst, npages);
>   	migrate_device_finalize(src, dst, npages);
> -	drm_pagemap_migrate_unmap_pages(devmem_allocation->dev, pagemap_addr, dst, npages,
> -					DMA_FROM_DEVICE, &state);
>   
>   err_free:
>   	kvfree(buf);
> @@ -1305,14 +1305,14 @@ static int __drm_pagemap_migrate_to_ram(struct vm_area_struct *vas,
>   		goto err_finalize;
>   
>   err_finalize:
> -	if (err)
> -		drm_pagemap_migration_unlock_put_pages(npages, migrate.dst);
> -	migrate_vma_pages(&migrate);
> -	migrate_vma_finalize(&migrate);
>   	if (dev)
>   		drm_pagemap_migrate_unmap_pages(dev, pagemap_addr, migrate.dst,
>   						npages, DMA_FROM_DEVICE,
>   						&state);
> +	if (err)
> +		drm_pagemap_migration_unlock_put_pages(npages, migrate.dst);
> +	migrate_vma_pages(&migrate);
> +	migrate_vma_finalize(&migrate);

LGTM
Reviewed-by: Himal Prasad Ghimiray <[email protected]>

>   err_free:
>   	kvfree(buf);
>   err_out: