Re: [PATCH v21 7/9] rust: page: convert to `AlwaysRefCounted`

[Alice Ryhl]

On Thu, Sep 10, 2026 at 11:01 AM Andreas Hindborg <a.hindborg@xxxxxxxxxx> wrote:
>
> `struct page` is managed by a native reference count, and kernel C
> code routinely takes its own references to pages, for example when a
> page is inserted into a VMA with `vm_insert_page()`.
>
> Thus, implement `RefCounted` for `Page`, backed by `get_page()` and
> `put_page()`, mark it `AlwaysRefCounted`, and return `ARef<Page>` from
> `Page::alloc_page()`. The page is freed when the last reference to it is
> dropped; for the order-0 pages allocated here, this is equivalent to
> `__free_pages()`.
>
> This also allows `Page` references to be returned as borrowed
> references without owning the `struct page`. Remove `BorrowedPage`
> and update users to use `&Page` and `ARef<Page>`.
>
> Assisted-by: LLM
> Suggested-by: Alice Ryhl <aliceryhl@xxxxxxxxxx>
> Signed-off-by: Andreas Hindborg <a.hindborg@xxxxxxxxxx>

Reviewed-by: Alice Ryhl <aliceryhl@xxxxxxxxxx>