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From: Alice Ryhl <aliceryhl@google.com>
To: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>,
	"Liam R. Howlett" <Liam.Howlett@oracle.com>,
	 Andrew Morton <akpm@linux-foundation.org>,
	Danilo Krummrich <dakr@kernel.org>,
	 Matthew Wilcox <willy@infradead.org>,
	Tamir Duberstein <tamird@gmail.com>,
	 Andreas Hindborg <a.hindborg@kernel.org>,
	Miguel Ojeda <ojeda@kernel.org>
Cc: "Boqun Feng" <boqun.feng@gmail.com>,
	"Gary Guo" <gary@garyguo.net>,
	"Björn Roy Baron" <bjorn3_gh@protonmail.com>,
	"Benno Lossin" <lossin@kernel.org>,
	"Trevor Gross" <tmgross@umich.edu>,
	linux-mm@kvack.org, rust-for-linux@vger.kernel.org,
	linux-kernel@vger.kernel.org, "Alice Ryhl" <aliceryhl@google.com>
Subject: [PATCH 0/2] Take ARCH_KMALLOC_MINALIGN into account for build-time XArray check
Date: Tue, 15 Jul 2025 13:46:33 +0000	[thread overview]
Message-ID: <20250715-align-min-allocator-v1-0-3e1b2a5516c0@google.com> (raw)

The Rust bindings for XArray include a build-time check to ensure that
you can only use the XArray with pointers that are 4-byte aligned.
Because of that, there is currently a build failure if you attempt to
create an XArray<KBox<T>> where T is a 1-byte or 2-byte aligned type.
However, this error is incorrect as KBox<_> is guaranteed to be a
pointer that comes from kmalloc, and kmalloc always produces pointers
that are at least 4-byte aligned.

To fix this, we augment the compile-time logic that computes the
alignment of KBox<_> to take the minimum alignment of its allocator into
account.

This series is based on top of rust-next.

Signed-off-by: Alice Ryhl <aliceryhl@google.com>
---
Alice Ryhl (2):
      rust: alloc: specify the minimum alignment of each allocator
      rust: alloc: take the allocator into account for FOREIGN_ALIGN

 rust/kernel/alloc.rs           |  8 ++++++++
 rust/kernel/alloc/allocator.rs |  8 ++++++++
 rust/kernel/alloc/kbox.rs      | 15 +++++++++++----
 rust/kernel/sync/arc.rs        |  6 +++---
 4 files changed, 30 insertions(+), 7 deletions(-)
---
base-commit: a68a6bef0e75fb9e5aea1399d8538f4e3584dab1
change-id: 20250715-align-min-allocator-b31aee53cbda

Best regards,
-- 
Alice Ryhl <aliceryhl@google.com>


             reply	other threads:[~2025-07-15 13:46 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-07-15 13:46 Alice Ryhl [this message]
2025-07-15 13:46 ` [PATCH 1/2] rust: alloc: specify the minimum alignment of each allocator Alice Ryhl
2025-07-15 14:05   ` Danilo Krummrich
2025-07-15 14:35     ` Alice Ryhl
2025-07-15 14:39       ` Danilo Krummrich
2025-07-15 16:01   ` Benno Lossin
2025-07-15 13:46 ` [PATCH 2/2] rust: alloc: take the allocator into account for FOREIGN_ALIGN Alice Ryhl
2025-07-15 14:19   ` Danilo Krummrich
2025-07-16  9:46     ` Alice Ryhl
2025-07-15 16:00   ` Benno Lossin
2025-07-15 16:23     ` Danilo Krummrich

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