Re: [PATCH v3 3/3] rust: alloc: move `NumaNode` to the `numa` module

[Gary Guo]

On Tue Sep 29, 2026 at 6:56 PM BST, Andreas Hindborg wrote:
> `NumaNode` identifies a NUMA node and is not specific to the allocator API.
> Move it from the `alloc` module to the `numa` module so that NUMA related
> items live together.
>
> No functional change.
>
> Suggested-by: Alice Ryhl <aliceryhl@xxxxxxxxxx>
> Link: https://lore.kernel.org/all/aiZvKPFCkqJUsP0a@xxxxxxxxxx/
> Signed-off-by: Andreas Hindborg <a.hindborg@xxxxxxxxxx>
> ---
>  rust/kernel/alloc.rs           | 30 ++++--------------------------
>  rust/kernel/alloc/allocator.rs |  6 +++---
>  rust/kernel/alloc/kbox.rs      |  4 ++--
>  rust/kernel/alloc/kvec.rs      |  4 ++--
>  rust/kernel/numa.rs            | 35 ++++++++++++++++++++++++++++++++++-
>  5 files changed, 45 insertions(+), 34 deletions(-)
>
> diff --git a/rust/kernel/alloc.rs b/rust/kernel/alloc.rs
> index 21067bde6860..9daddf540e7d 100644
> --- a/rust/kernel/alloc.rs
> +++ b/rust/kernel/alloc.rs
> @@ -22,7 +22,10 @@
>  #[derive(Copy, Clone, PartialEq, Eq, Debug)]
>  pub struct AllocError;
>  
> -use crate::prelude::*;
> +use crate::{
> +    numa::NumaNode,
> +    prelude::*, //
> +};
>  
>  use core::{
>      alloc::Layout,
> @@ -114,31 +117,6 @@ pub mod flags {
>      pub const __GFP_NOWARN: Flags = Flags(bindings::__GFP_NOWARN);
>  }
>  
> -/// Non Uniform Memory Access (NUMA) node identifier.
> -#[derive(Clone, Copy, PartialEq)]
> -pub struct NumaNode(i32);
> -
> -impl NumaNode {
> -    /// Create a new NUMA node identifier (non-negative integer).
> -    ///
> -    /// Returns [`EINVAL`] if a negative id or an id exceeding [`bindings::MAX_NUMNODES`] is
> -    /// specified.
> -    pub fn new(node: i32) -> Result<Self> {
> -        // MAX_NUMNODES never exceeds 2**10 because NODES_SHIFT is 0..10.
> -        if node < 0 || node >= bindings::MAX_NUMNODES as i32 {
> -            return Err(EINVAL);
> -        }
> -        Ok(Self(node))
> -    }
> -}
> -
> -/// Specify necessary constant to pass the information to Allocator that the caller doesn't care
> -/// about the NUMA node to allocate memory from.
> -impl NumaNode {
> -    /// No node preference.
> -    pub const NO_NODE: NumaNode = NumaNode(bindings::NUMA_NO_NODE);
> -}
> -
>  /// The kernel's [`Allocator`] trait.
>  ///
>  /// An implementation of [`Allocator`] can allocate, re-allocate and free memory buffers described
> diff --git a/rust/kernel/alloc/allocator.rs b/rust/kernel/alloc/allocator.rs
> index cd4203f27aed..4af50e20933b 100644
> --- a/rust/kernel/alloc/allocator.rs
> +++ b/rust/kernel/alloc/allocator.rs
> @@ -11,12 +11,12 @@
>  use super::{
>      AllocError,
>      Allocator,
> -    Flags,
> -    NumaNode, //
> +    Flags, //
>  };
>  
>  use crate::{
>      bindings,
> +    numa::NumaNode,
>      page, //
>  };
>  
> @@ -122,7 +122,7 @@ unsafe fn call(
>          // - Those functions provide the guarantees of this function.
>          let raw_ptr = unsafe {
>              // If `size == 0` and `ptr != NULL` the memory behind the pointer is freed.
> -            self.0(ptr.cast(), size, layout.align(), flags.0, nid.0).cast()
> +            self.0(ptr.cast(), size, layout.align(), flags.0, nid.as_raw()).cast()
>          };
>  
>          let ptr = if size == 0 {
> diff --git a/rust/kernel/alloc/kbox.rs b/rust/kernel/alloc/kbox.rs
> index c63d6acdbb6f..0fa736c81287 100644
> --- a/rust/kernel/alloc/kbox.rs
> +++ b/rust/kernel/alloc/kbox.rs
> @@ -13,12 +13,12 @@
>  use super::{
>      AllocError,
>      Allocator,
> -    Flags,
> -    NumaNode, //
> +    Flags, //
>  };
>  
>  use crate::{
>      fmt,
> +    numa::NumaNode,
>      page::AsPageIter,
>      prelude::*,
>      types::ForeignOwnable, //
> diff --git a/rust/kernel/alloc/kvec.rs b/rust/kernel/alloc/kvec.rs
> index c7546b9da4fa..b669ca10b3f7 100644
> --- a/rust/kernel/alloc/kvec.rs
> +++ b/rust/kernel/alloc/kvec.rs
> @@ -14,12 +14,12 @@
>      AllocError,
>      Allocator,
>      Box,
> -    Flags,
> -    NumaNode, //
> +    Flags, //
>  };
>  
>  use crate::{
>      fmt,
> +    numa::NumaNode,
>      page::{
>          AsPageIter,
>          PAGE_SIZE, //
> diff --git a/rust/kernel/numa.rs b/rust/kernel/numa.rs
> index 164e622d325f..4a3a880308f3 100644
> --- a/rust/kernel/numa.rs
> +++ b/rust/kernel/numa.rs
> @@ -4,12 +4,15 @@
>  //!
>  //! C header: [`include/linux/nodemask.h`](srctree/include/linux/nodemask.h)
>  
> -use crate::bindings;
>  #[cfg(CONFIG_NUMA)]
>  use crate::sync::atomic::{
>      Atomic,
>      Relaxed, //
>  };
> +use crate::{
> +    bindings,
> +    prelude::*, //
> +};
>  
>  /// Returns the number of online NUMA nodes.
>  #[inline]
> @@ -27,3 +30,33 @@ pub fn num_online_nodes() -> u32 {
>          bindings::nr_online_nodes
>      }
>  }
> +
> +/// Non Uniform Memory Access (NUMA) node identifier.
> +#[derive(Clone, Copy, PartialEq)]
> +pub struct NumaNode(i32);

FWIW the C type is nodemask_t and this should have mask in the name too. It is
not an identifier. That said, this is an existing issue, so shouldn't block the
move.

Best,
Gary

> +
> +impl NumaNode {
> +    /// Create a new NUMA node identifier (non-negative integer).
> +    ///
> +    /// Returns [`EINVAL`] if a negative id or an id exceeding [`bindings::MAX_NUMNODES`] is
> +    /// specified.
> +    pub fn new(node: i32) -> Result<Self> {
> +        // MAX_NUMNODES never exceeds 2**10 because NODES_SHIFT is 0..10.
> +        if node < 0 || node >= bindings::MAX_NUMNODES as i32 {
> +            return Err(EINVAL);
> +        }
> +        Ok(Self(node))
> +    }
> +
> +    /// Get the raw representation of this node identifier.
> +    pub(crate) fn as_raw(self) -> i32 {
> +        self.0
> +    }
> +}
> +
> +/// Specify necessary constant to pass the information to Allocator that the caller doesn't care
> +/// about the NUMA node to allocate memory from.
> +impl NumaNode {
> +    /// No node preference.
> +    pub const NO_NODE: NumaNode = NumaNode(bindings::NUMA_NO_NODE);
> +}