Re: [PATCH 1/2] drm/nouveau/dmem: pin VRAM for the whole registered range

[lyude]

Reviewed-by: Lyude Paul <lyude@xxxxxxxxxx>

On Mon, 2026-08-17 at 14:50 +0800, Junrui Luo via B4 Relay wrote:
> From: Junrui Luo <moonafterrain@xxxxxxxxxxx>
> 
> Commit c32287471077 ("gpu/drm/nouveau: enable THP support for GPU
> memory
> migration") grew the device-private region that
> nouveau_dmem_chunk_alloc() registers from DMEM_CHUNK_SIZE to
> DMEM_CHUNK_SIZE * NR_CHUNKS, but left the VRAM buffer object backing
> that
> region at DMEM_CHUNK_SIZE.
> 
> nouveau_dmem_page_addr() returns chunk->bo->offset plus the page's
> offset
> within the registered region, so every page past the first chunk
> resolves
> to VRAM outside the buffer object.
> 
> Size the buffer object to the region it backs.
> 
> Fixes: c32287471077 ("gpu/drm/nouveau: enable THP support for GPU
> memory migration")
> Reported-by: Yuhao Jiang <danisjiang@xxxxxxxxx>
> Assisted-by: Claude:claude-opus-5
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Junrui Luo <moonafterrain@xxxxxxxxxxx>
> ---
>  drivers/gpu/drm/nouveau/nouveau_dmem.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/nouveau/nouveau_dmem.c
> b/drivers/gpu/drm/nouveau/nouveau_dmem.c
> index 9442ec6e1f6c..356ff8f3c1b8 100644
> --- a/drivers/gpu/drm/nouveau/nouveau_dmem.c
> +++ b/drivers/gpu/drm/nouveau/nouveau_dmem.c
> @@ -325,8 +325,8 @@ nouveau_dmem_chunk_alloc(struct nouveau_drm *drm,
> struct page **ppage,
>  	chunk->pagemap.ops = &nouveau_dmem_pagemap_ops;
>  	chunk->pagemap.owner = drm->dev;
>  
> -	ret = nouveau_bo_new_pin(&drm->client,
> NOUVEAU_GEM_DOMAIN_VRAM, DMEM_CHUNK_SIZE,
> -				 &chunk->bo);
> +	ret = nouveau_bo_new_pin(&drm->client,
> NOUVEAU_GEM_DOMAIN_VRAM,
> +				 DMEM_CHUNK_SIZE * NR_CHUNKS,
> &chunk->bo);
>  	if (ret)
>  		goto out_release;
>