Re: [PATCH v14 1/8] mm: rust: add abstraction for struct mm_struct

[Gary Guo <gary@garyguo.net>]

On Thu, 13 Feb 2025 11:04:00 +0000
Alice Ryhl <aliceryhl@google.com> wrote:

> These abstractions allow you to reference a `struct mm_struct` using
> both mmgrab and mmget refcounts. This is done using two Rust types:
> 
> * Mm - represents an mm_struct where you don't know anything about the
>   value of mm_users.
> * MmWithUser - represents an mm_struct where you know at compile time
>   that mm_users is non-zero.
> 
> This allows us to encode in the type system whether a method requires
> that mm_users is non-zero or not. For instance, you can always call
> `mmget_not_zero` but you can only call `mmap_read_lock` when mm_users is
> non-zero.
> 
> The struct is called Mm to keep consistency with the C side.
> 
> The ability to obtain `current->mm` is added later in this series.
> 
> Acked-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
> Acked-by: Balbir Singh <balbirs@nvidia.com>
> Reviewed-by: Andreas Hindborg <a.hindborg@kernel.org>
> Signed-off-by: Alice Ryhl <aliceryhl@google.com>

Reviewed-by: Gary Guo <gary@garyguo.net>

> ---
>  rust/helpers/helpers.c |   1 +
>  rust/helpers/mm.c      |  39 +++++++++
>  rust/kernel/lib.rs     |   1 +
>  rust/kernel/mm.rs      | 209 +++++++++++++++++++++++++++++++++++++++++++++++++
>  4 files changed, 250 insertions(+)