Re: [PATCH V3 3/9] dax/fsdev: clear vmemmap_shift when binding static pgmap

[Dave Jiang]

On 5/30/26 9:50 AM, John Groves wrote:
> From: John Groves <John@xxxxxxxxxx>
> 
> Clear pgmap->vmemmap_shift for static DAX devices. When rebinding a static
> device from device_dax (which may set vmemmap_shift based on alignment) to
> fsdev_dax, the stale vmemmap_shift persists on the shared pgmap. Explicitly
> zero it before devm_memremap_pages() so the vmemmap is built for order-0
> folios as fsdev requires.
> 
> Fixes: d5406bd458b0a ("dax: add fsdev.c driver for fs-dax on character dax")
> Signed-off-by: John Groves <john@xxxxxxxxxx>

Reviewed-by: Dave Jiang <dave.jiang@xxxxxxxxx>

> ---
>  drivers/dax/fsdev.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/dax/fsdev.c b/drivers/dax/fsdev.c
> index f315533b299e9..dbd722ed7ab05 100644
> --- a/drivers/dax/fsdev.c
> +++ b/drivers/dax/fsdev.c
> @@ -237,6 +237,7 @@ static int fsdev_dax_probe(struct dev_dax *dev_dax)
>  		}
>  
>  		pgmap = dev_dax->pgmap;
> +		pgmap->vmemmap_shift = 0;
>  	} else {
>  		size_t pgmap_size;
>