Claude review: rust: add `Ownable` trait and `Owned` type

[Claude Code Review Bot <claude-review@example.com>]

Overall Series Review

Subject: rust: add `Ownable` trait and `Owned` type
Author: Andreas Hindborg <a.hindborg@kernel.org>
Patches: 11
Reviewed: 2026-02-27T15:11:56.449708

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This is v16 of a well-iterated series by Andreas Hindborg (with contributions from Asahi Lina and Oliver Mangold) that introduces a new `Ownable` trait and `Owned<T>` pointer type for the kernel's Rust abstractions. The core idea is sound and fills an important gap: allowing C-allocated objects to be uniquely owned by Rust with custom drop logic, analogous to `KBox<T>` but delegating resource management to the type itself.

The series splits `AlwaysRefCounted` into `RefCounted` (for `ARef<T>`) and a marker trait `AlwaysRefCounted` (for the `&T -> ARef<T>` upgrade), which correctly addresses the soundness issue that arises when a type can be both `Ownable` (unique ownership) and allow `&T -> ARef<T>` conversion (which would violate uniqueness). This is the right design.

The series is well-structured and has accumulated extensive review over 16 versions. The code is generally clean and the safety documentation is thorough.

**Issues found:**
- Minor typo in a safety comment
- Questionable `// ` trailing comment markers used as rustfmt anchors
- A doc link that points to the wrong type
- Some minor inconsistencies in SAFETY comments for `AlwaysRefCounted` marker impls

No major soundness or correctness issues identified.

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Generated by Claude Code Patch Reviewer