Re: [PATCH] rust: mm: Mark VmaNew as transparent

[Greg KH <gregkh@linuxfoundation.org>]

On Tue, Aug 12, 2025 at 03:26:56PM +0200, Baptiste Lepers wrote:
> Unsafe code in VmaNew's methods assumes that the type has the same
> layout as the inner `bindings::vm_area_struct`. This is not guaranteed by
> the default struct representation in Rust, but requires specifying the
> `transparent` representation.
> 
> Fixes: dcb81aeab406e ("mm: rust: add VmaNew for f_ops->mmap()")
> Signed-off-by: Baptiste Lepers <baptiste.lepers@gmail.com>
> ---
>  rust/kernel/mm/virt.rs | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/rust/kernel/mm/virt.rs b/rust/kernel/mm/virt.rs
> index 6086ca981b06..a1bfa4e19293 100644
> --- a/rust/kernel/mm/virt.rs
> +++ b/rust/kernel/mm/virt.rs
> @@ -209,6 +209,7 @@ pub fn vm_insert_page(&self, address: usize, page: &Page) -> Result {
>  ///
>  /// For the duration of 'a, the referenced vma must be undergoing initialization in an
>  /// `f_ops->mmap()` hook.
> +#[repr(transparent)]
>  pub struct VmaNew {
>      vma: VmaRef,
>  }
> -- 
> 2.43.0
> 
> 

Hi,

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