Re: [PATCH 1/2] mm/page_ext: Add page_ext_get_phys()

[Jörg Rödel]

On Mon, Jan 19, 2026 at 02:22:45PM +0000, Mostafa Saleh wrote:
> +static inline struct page_ext *page_ext_get_phys(phys_addr_t phys)

The name is misleading as it indicates that the function returns a physical
address. Maybe name it page_ext_from_phys()?

> +{
> +	return NULL;
> +}
> +
>  static inline void page_ext_put(struct page_ext *page_ext)
>  {
>  }
> diff --git a/mm/page_ext.c b/mm/page_ext.c
> index 297e4cd8ce90..5fe65a0ac4f3 100644
> --- a/mm/page_ext.c
> +++ b/mm/page_ext.c
> @@ -538,6 +538,29 @@ struct page_ext *page_ext_get(const struct page *page)
>  	return page_ext;
>  }
>  
> +/**
> + * page_ext_get_phys() - Get the page_ext structure for a physical address.
> + * @phys: The physical address to query.
> + *
> + * This function safely gets the `struct page_ext` associated with a given
> + * physical address. It performs validation to ensure the address corresponds
> + * to a valid, online struct page before attempting to access it.
> + * It should return NULL for (MMIO, ZONE_DEVICE, holes, offline memory)

It should?

-Joerg