[PATCH v20 4/8] rust: page: convert to `Ownable`'

[Alice Ryhl]

On Mon, Aug 24, 2026 at 01:17:56PM +0200, Andreas Hindborg wrote:
> +        // SAFETY: We just successfully allocated a page, so we now have ownership of the newly
> +        // allocated page. We transfer that ownership to the new `Owned<Page>` object.
> +        // Since `Page` is transparent, we can cast the pointer directly.
> +        Ok(unsafe { Owned::from_raw(page.cast()) })

This doesn't satisfy the safety requirements of Owned::from_raw()
because the page may be used with vm_insert_page(), which increments its
refcount and causes it to be shared the vma system, and this occurs
before Page::release() is called.

Alice