[PATCH 1/4] rust: alloc: replace aligned_size() with Kmalloc::aligned_layout()

[Alice Ryhl]

On Thu, Jul 31, 2025 at 05:48:06PM +0200, Danilo Krummrich wrote:
> aligned_size() dates back to when Rust did support kmalloc() only, but
> is now used in ReallocFunc::call() and hence for all allocators.
> 
> However, the additional padding applied by aligned_size() is only
> required by the kmalloc() allocator backend.
> 
> Hence, replace aligned_size() with Kmalloc::aligned_layout() and use it
> for the affected allocators, i.e. kmalloc() and kvmalloc(), only.
> 
> While at it, make Kmalloc::aligned_layout() public, such that Rust
> abstractions, which have to call subsystem specific kmalloc() based
> allocation primitives directly, can make use of it.
> 
> Fixes: 8a799831fc63 ("rust: alloc: implement `ReallocFunc`")
> Signed-off-by: Danilo Krummrich <dakr at kernel.org>

I guess vmalloc handles alignment in a different way ... ok makes sense
to me.

Reviewed-by: Alice Ryhl <aliceryhl at google.com>