linux/rust/kernel/alloc, branch v6.17

rust: alloc: fix `rusttest` by providing `Cmalloc::aligned_layout` too

2025-08-16T23:29:21Z

Commit fde578c86281 ("rust: alloc: replace aligned_size() with Kmalloc::aligned_layout()") provides a public `aligned_layout` function in `Kamlloc`, but not in `Cmalloc`, and thus uses of it will trigger an error in `rusttest`. Such a user appeared in the following commit 22ab0641b939 ("rust: drm: ensure kmalloc() compatible Layout"): error[E0599]: no function or associated item named `aligned_layout` found for struct `alloc::allocator_test::Cmalloc` in the current scope --> rust/kernel/drm/device.rs:100:31 | 100 | let layout = Kmalloc::aligned_layout(Layout::new::()); | ^^^^^^^^^^^^^^ function or associated item not found in `Cmalloc` | ::: rust/kernel/alloc/allocator_test.rs:19:1 | 19 | pub struct Cmalloc; | ------------------ function or associated item `aligned_layout` not found for this struct Thus add an equivalent one for `Cmalloc`. Fixes: fde578c86281 ("rust: alloc: replace aligned_size() with Kmalloc::aligned_layout()") Signed-off-by: Miguel Ojeda Link: https://lore.kernel.org/r/20250816204215.2719559-1-ojeda@kernel.org Signed-off-by: Danilo Krummrich

rust: alloc: replace aligned_size() with Kmalloc::aligned_layout()

2025-08-11T21:20:53Z

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`") Reviewed-by: Alice Ryhl Link: https://lore.kernel.org/r/20250731154919.4132-2-dakr@kernel.org [ Remove `const` from Kmalloc::aligned_layout(). - Danilo ] Signed-off-by: Danilo Krummrich

Merge tag 'alloc-next-v6.17-2025-07-15' of https://github.com/Rust-for-Linux/linux into rust-next

2025-07-15T21:42:55Z

Pull alloc and DMA updates from Danilo Krummrich: Box: - Implement Borrow / BorrowMut for Box. Vec: - Implement Default for Vec. - Implement Borrow / BorrowMut for Vec. DMA: - Clarify wording and be consistent in 'coherent' nomenclature. - Convert the read!() / write!() macros to return a Result. - Add as_slice() / write() methods in CoherentAllocation. - Fix doc-comment of dma_handle(). - Expose count() and size() in CoherentAllocation and add the corresponding type invariants. - Implement CoherentAllocation::dma_handle_with_offset(). - Require mutable reference for as_slice_mut() and write(). MAINTAINERS: - Add Vlastimil Babka, Liam R. Howlett, Uladzislau Rezki and Lorenzo Stoakes as reviewers (thanks everyone). * tag 'alloc-next-v6.17-2025-07-15' of https://github.com/Rust-for-Linux/linux: MAINTAINERS: add mm folks as reviewers to rust alloc rust: dma: require mutable reference for as_slice_mut() and write() rust: dma: add dma_handle_with_offset method to CoherentAllocation rust: dma: expose the count and size of CoherentAllocation rust: dma: fix doc-comment of dma_handle() rust: dma: add as_slice/write functions for CoherentAllocation rust: dma: convert the read/write macros to return Result rust: dma: clarify wording and be consistent in `coherent` nomenclature rust: alloc: implement `Borrow` and `BorrowMut` for `KBox` rust: alloc: implement `Borrow` and `BorrowMut` for `Vec` rust: vec: impl Default for Vec with any allocator

rust: types: add FOREIGN_ALIGN to ForeignOwnable

2025-07-14T21:55:24Z

The current implementation of `ForeignOwnable` is leaking the type of the opaque pointer to consumers of the API. This allows consumers of the opaque pointer to rely on the information that can be extracted from the pointer type. To prevent this, change the API to the version suggested by Maira Canal (link below): Remove `ForeignOwnable::PointedTo` in favor of a constant, which specifies the alignment of the pointers returned by `into_foreign`. With this change, `ArcInner` no longer needs `pub` visibility, so change it to private. Suggested-by: Alice Ryhl Suggested-by: Maíra Canal Link: https://lore.kernel.org/r/20240309235927.168915-3-mcanal@igalia.com Acked-by: Danilo Krummrich Reviewed-by: Benno Lossin Signed-off-by: Andreas Hindborg Reviewed-by: Alice Ryhl Link: https://lore.kernel.org/r/20250612-pointed-to-v3-1-b009006d86a1@kernel.org Signed-off-by: Miguel Ojeda

rust: enable `clippy::ptr_as_ptr` lint

2025-06-22T21:08:42Z

In Rust 1.51.0, Clippy introduced the `ptr_as_ptr` lint [1]: > Though `as` casts between raw pointers are not terrible, > `pointer::cast` is safer because it cannot accidentally change the > pointer's mutability, nor cast the pointer to other types like `usize`. There are a few classes of changes required: - Modules generated by bindgen are marked `#[allow(clippy::ptr_as_ptr)]`. - Inferred casts (` as _`) are replaced with `.cast()`. - Ascribed casts (` as *... T`) are replaced with `.cast::()`. - Multistep casts from references (` as *const _ as *const T`) are replaced with `core::ptr::from_ref(&x).cast()` with or without `::` according to the previous rules. The `core::ptr::from_ref` call is required because `(x as *const _).cast::()` results in inference failure. - Native literal C strings are replaced with `c_str!().as_char_ptr()`. - `*mut *mut T as _` is replaced with `let *mut *const T = (*mut *mut T)`.cast();` since pointer to pointer can be confusing. Apply these changes and enable the lint -- no functional change intended. Link: https://rust-lang.github.io/rust-clippy/master/index.html#ptr_as_ptr [1] Reviewed-by: Benno Lossin Reviewed-by: Boqun Feng Signed-off-by: Tamir Duberstein Acked-by: Viresh Kumar Acked-by: Greg Kroah-Hartman Acked-by: Tejun Heo Acked-by: Danilo Krummrich Link: https://lore.kernel.org/r/20250615-ptr-as-ptr-v12-1-f43b024581e8@gmail.com [ Added `.cast()` for `opp`. - Miguel ] Signed-off-by: Miguel Ojeda

rust: alloc: implement `Borrow` and `BorrowMut` for `KBox`

2025-06-18T21:09:41Z

Implement `Borrow` and `BorrowMut` for `KBox`. This allows `KBox` to be used in generic APIs asking for types implementing those traits. `T` and `&mut T` also implement those traits allowing users to use either owned, borrowed and heap-owned values. Reviewed-by: Alice Ryhl Reviewed-by: Benno Lossin Signed-off-by: Alexandre Courbot Link: https://lore.kernel.org/r/20250616-borrow_impls-v4-3-36f9beb3fe6a@nvidia.com Signed-off-by: Danilo Krummrich

rust: alloc: implement `Borrow` and `BorrowMut` for `Vec`

2025-06-18T21:09:21Z

Implement `Borrow<[T]>` and `BorrowMut<[T]>` for `Vec`. This allows `Vec` to be used in generic APIs asking for types implementing those traits. `[T; N]` and `&mut [T]` also implement those traits allowing users to use either owned, borrowed and heap-owned values. The implementation leverages `as_slice` and `as_mut_slice`. Reviewed-by: Alice Ryhl Reviewed-by: Benno Lossin Signed-off-by: Alexandre Courbot Link: https://lore.kernel.org/r/20250616-borrow_impls-v4-1-36f9beb3fe6a@nvidia.com Signed-off-by: Danilo Krummrich

rust: vec: impl Default for Vec with any allocator

2025-06-11T14:35:10Z

The implementation of Default is restricted to only work with kmalloc vectors for no good reason. This means I have to use mem::replace(&mut my_vec, KVVec::new()) in Rust Binder instead of `mem::take(&mut my_vec)`. Thus, expand the impl of Default to work with any allocator including kvmalloc. Signed-off-by: Alice Ryhl Reviewed-by: Benno Lossin Link: https://lore.kernel.org/r/20250610-vec-default-v1-1-7bb2c97d75a0@google.com Signed-off-by: Danilo Krummrich

rust: alloc: add missing Markdown code span

2025-05-25T20:58:35Z

Add missing Markdown code span. This was found using the Clippy `doc_markdown` lint, which we may want to enable. Fixes: dd09538fb409 ("rust: alloc: implement `Cmalloc` in module allocator_test") Reviewed-by: Benno Lossin Acked-by: Danilo Krummrich Link: https://lore.kernel.org/r/20250324210359.1199574-5-ojeda@kernel.org Signed-off-by: Miguel Ojeda

rust: remove unneeded Rust 1.87.0 `allow(clippy::ptr_eq)`

2025-05-22T09:46:50Z

For the Rust 1.87.0 release, Clippy was expected to warn with: error: use `core::ptr::eq` when comparing raw pointers --> rust/kernel/list.rs:438:12 | 438 | if self.first == item { | ^^^^^^^^^^^^^^^^^^ help: try: `core::ptr::eq(self.first, item)` | = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#ptr_eq = note: `-D clippy::ptr-eq` implied by `-D warnings` = help: to override `-D warnings` add `#[allow(clippy::ptr_eq)]` However, a backport to relax a bit the `clippy::ptr_eq` finally landed, and thus Clippy did not warn by the time the release happened. Thus remove the `allow`s added back then, which were added just in case the backport did not land in time. See commit a39f30870927 ("rust: allow Rust 1.87.0's `clippy::ptr_eq` lint") for details. Link: https://github.com/rust-lang/rust/pull/140859 [1] Reviewed-by: Alice Ryhl Link: https://lore.kernel.org/r/20250520182125.806758-1-ojeda@kernel.org [ Reworded for clarity. - Miguel ] Signed-off-by: Miguel Ojeda