Re: [PATCH v7 4/4] rust: add abstraction for `struct page`

[Abdiel Janulgue <abdiel@redhat.com>]

Hi,

On 28/05/2024 17:58, Alice Ryhl wrote:
> Adds a new struct called `Page` that wraps a pointer to `struct page`.
> This struct is assumed to hold ownership over the page, so that Rust
> code can allocate and manage pages directly.
> 
> +
> +impl Drop for Page {
> +    fn drop(&mut self) {
> +        // SAFETY: By the type invariants, we have ownership of the page and can free it.
> +        unsafe { bindings::__free_pages(self.page.as_ptr(), 0) };
> +    }
> +}
> 

What about cases where the struct page pointer is not owned or allocated 
by this wrapper? For example, pages returned vmalloc_to_page()?
Any thoughts about exposing a provision to avoid freeing those pages 
during Drop?

We've been experimenting in adapting this Page wrapper in advance for 
page management within the Nova DRM driver.

/Abdiel