Add support for specifying NUMA ids in Rust allocators as an Option
(i. e. providing `None` as nid corresponds to NUMA_NO_NODE). This
will allow to specify node to use for allocation of e. g. {KV}Box.

Signed-off-by: Vitaly Wool <vitaly.wool@konsulko.se>
---
 rust/helpers/slab.c            |  9 +++++----
 rust/helpers/vmalloc.c         |  4 ++--
 rust/kernel/alloc.rs           | 28 ++++++++++++++++++++++++++--
 rust/kernel/alloc/allocator.rs | 26 ++++++++++++++++++--------
 rust/kernel/alloc/kvec.rs      |  3 ++-
 5 files changed, 53 insertions(+), 17 deletions(-)

diff --git a/rust/helpers/slab.c b/rust/helpers/slab.c
index 5e9e8dd2bba0..ab1cf72f8353 100644
--- a/rust/helpers/slab.c
+++ b/rust/helpers/slab.c
@@ -3,13 +3,14 @@
 #include <linux/slab.h>
 
 void * __must_check __realloc_size(2)
-rust_helper_krealloc(const void *objp, size_t new_size, unsigned long align, gfp_t flags)
+rust_helper_krealloc_node(const void *objp, size_t new_size, unsigned long align, gfp_t flags,
+			  int nid)
 {
-	return krealloc(objp, new_size, flags);
+	return krealloc_node(objp, new_size, flags, nid);
 }
 
 void * __must_check __realloc_size(2)
-rust_helper_kvrealloc(const void *p, size_t size, unsigned long align, gfp_t flags)
+rust_helper_kvrealloc_node(const void *p, size_t size, unsigned long align, gfp_t flags, int nid)
 {
-	return kvrealloc(p, size, flags);
+	return kvrealloc_node(p, size, flags, nid);
 }
diff --git a/rust/helpers/vmalloc.c b/rust/helpers/vmalloc.c
index 4618c0b79283..9131279222fa 100644
--- a/rust/helpers/vmalloc.c
+++ b/rust/helpers/vmalloc.c
@@ -3,7 +3,7 @@
 #include <linux/vmalloc.h>
 
 void * __must_check __realloc_size(2)
-rust_helper_vrealloc(const void *p, size_t size, unsigned long align, gfp_t flags)
+rust_helper_vrealloc_node(const void *p, size_t size, unsigned long align, gfp_t flags, int node)
 {
-	return vrealloc_node(p, size, align, flags, NUMA_NO_NODE);
+	return vrealloc_node(p, size, align, flags, node);
 }
diff --git a/rust/kernel/alloc.rs b/rust/kernel/alloc.rs
index a2c49e5494d3..1e26c2a7f47c 100644
--- a/rust/kernel/alloc.rs
+++ b/rust/kernel/alloc.rs
@@ -156,7 +156,30 @@ pub unsafe trait Allocator {
     fn alloc(layout: Layout, flags: Flags) -> Result<NonNull<[u8]>, AllocError> {
         // SAFETY: Passing `None` to `realloc` is valid by its safety requirements and asks for a
         // new memory allocation.
-        unsafe { Self::realloc(None, layout, Layout::new::<()>(), flags) }
+        unsafe { Self::realloc(None, layout, Layout::new::<()>(), flags, None) }
+    }
+
+    /// Allocate memory based on `layout`, `flags` and `nid`.
+    ///
+    /// On success, returns a buffer represented as `NonNull<[u8]>` that satisfies the layout
+    /// constraints (i.e. minimum size and alignment as specified by `layout`).
+    ///
+    /// This function is equivalent to `realloc` when called with `None`.
+    ///
+    /// # Guarantees
+    ///
+    /// When the return value is `Ok(ptr)`, then `ptr` is
+    /// - valid for reads and writes for `layout.size()` bytes, until it is passed to
+    ///   [`Allocator::free`] or [`Allocator::realloc`],
+    /// - aligned to `layout.align()`,
+    ///
+    /// Additionally, `Flags` are honored as documented in
+    /// <https://docs.kernel.org/core-api/mm-api.html#mm-api-gfp-flags>.
+    fn alloc_node(layout: Layout, flags: Flags, nid: Option<i32>)
+                -> Result<NonNull<[u8]>, AllocError> {
+        // SAFETY: Passing `None` to `realloc` is valid by its safety requirements and asks for a
+        // new memory allocation.
+        unsafe { Self::realloc(None, layout, Layout::new::<()>(), flags, nid) }
     }
 
     /// Re-allocate an existing memory allocation to satisfy the requested `layout`.
@@ -196,6 +219,7 @@ unsafe fn realloc(
         layout: Layout,
         old_layout: Layout,
         flags: Flags,
+        nid: Option<i32>,
     ) -> Result<NonNull<[u8]>, AllocError>;
 
     /// Free an existing memory allocation.
@@ -211,7 +235,7 @@ unsafe fn free(ptr: NonNull<u8>, layout: Layout) {
         // SAFETY: The caller guarantees that `ptr` points at a valid allocation created by this
         // allocator. We are passing a `Layout` with the smallest possible alignment, so it is
         // smaller than or equal to the alignment previously used with this allocation.
-        let _ = unsafe { Self::realloc(Some(ptr), Layout::new::<()>(), layout, Flags(0)) };
+        let _ = unsafe { Self::realloc(Some(ptr), Layout::new::<()>(), layout, Flags(0), None) };
     }
 }
 
diff --git a/rust/kernel/alloc/allocator.rs b/rust/kernel/alloc/allocator.rs
index a0d78c497974..5a0d0a57dfe5 100644
--- a/rust/kernel/alloc/allocator.rs
+++ b/rust/kernel/alloc/allocator.rs
@@ -58,18 +58,19 @@ fn aligned_size(new_layout: Layout) -> usize {
 ///
 /// One of the following: `krealloc`, `vrealloc`, `kvrealloc`.
 struct ReallocFunc(
-    unsafe extern "C" fn(*const crate::ffi::c_void, usize, usize, u32) -> *mut crate::ffi::c_void,
+    unsafe extern "C" fn(*const crate::ffi::c_void, usize, usize, u32, i32)
+                        -> *mut crate::ffi::c_void,
 );
 
 impl ReallocFunc {
     // INVARIANT: `krealloc` satisfies the type invariants.
-    const KREALLOC: Self = Self(bindings::krealloc);
+    const KREALLOC: Self = Self(bindings::krealloc_node);
 
     // INVARIANT: `vrealloc` satisfies the type invariants.
-    const VREALLOC: Self = Self(bindings::vrealloc);
+    const VREALLOC: Self = Self(bindings::vrealloc_node);
 
     // INVARIANT: `kvrealloc` satisfies the type invariants.
-    const KVREALLOC: Self = Self(bindings::kvrealloc);
+    const KVREALLOC: Self = Self(bindings::kvrealloc_node);
 
     /// # Safety
     ///
@@ -87,6 +88,7 @@ unsafe fn call(
         layout: Layout,
         old_layout: Layout,
         flags: Flags,
+        nid: Option<i32>,
     ) -> Result<NonNull<[u8]>, AllocError> {
         let size = aligned_size(layout);
         let ptr = match ptr {
@@ -100,6 +102,11 @@ unsafe fn call(
             None => ptr::null(),
         };
 
+        let c_nid = match nid {
+            None => bindings::NUMA_NO_NODE,
+            Some(n) => n,
+        };
+
         // SAFETY:
         // - `self.0` is one of `krealloc`, `vrealloc`, `kvrealloc` and thus only requires that
         //   `ptr` is NULL or valid.
@@ -110,7 +117,7 @@ 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).cast()
+            self.0(ptr.cast(), size, layout.align(), flags.0, c_nid).cast()
         };
 
         let ptr = if size == 0 {
@@ -134,9 +141,10 @@ unsafe fn realloc(
         layout: Layout,
         old_layout: Layout,
         flags: Flags,
+        nid: Option<i32>,
     ) -> Result<NonNull<[u8]>, AllocError> {
         // SAFETY: `ReallocFunc::call` has the same safety requirements as `Allocator::realloc`.
-        unsafe { ReallocFunc::KREALLOC.call(ptr, layout, old_layout, flags) }
+        unsafe { ReallocFunc::KREALLOC.call(ptr, layout, old_layout, flags, nid) }
     }
 }
 
@@ -151,10 +159,11 @@ unsafe fn realloc(
         layout: Layout,
         old_layout: Layout,
         flags: Flags,
+        nid: Option<i32>,
     ) -> Result<NonNull<[u8]>, AllocError> {
         // SAFETY: If not `None`, `ptr` is guaranteed to point to valid memory, which was previously
         // allocated with this `Allocator`.
-        unsafe { ReallocFunc::VREALLOC.call(ptr, layout, old_layout, flags) }
+        unsafe { ReallocFunc::VREALLOC.call(ptr, layout, old_layout, flags, nid) }
     }
 }
 
@@ -169,9 +178,10 @@ unsafe fn realloc(
         layout: Layout,
         old_layout: Layout,
         flags: Flags,
+        nid: Option<i32>
     ) -> Result<NonNull<[u8]>, AllocError> {
         // SAFETY: If not `None`, `ptr` is guaranteed to point to valid memory, which was previously
         // allocated with this `Allocator`.
-        unsafe { ReallocFunc::KVREALLOC.call(ptr, layout, old_layout, flags) }
+        unsafe { ReallocFunc::KVREALLOC.call(ptr, layout, old_layout, flags, nid) }
     }
 }
diff --git a/rust/kernel/alloc/kvec.rs b/rust/kernel/alloc/kvec.rs
index 1a0dd852a468..ef4f977ba012 100644
--- a/rust/kernel/alloc/kvec.rs
+++ b/rust/kernel/alloc/kvec.rs
@@ -633,6 +633,7 @@ pub fn reserve(&mut self, additional: usize, flags: Flags) -> Result<(), AllocEr
                 layout.into(),
                 self.layout.into(),
                 flags,
+                None,
             )?
         };
 
@@ -1058,7 +1059,7 @@ pub fn collect(self, flags: Flags) -> Vec<T, A> {
             // the type invariant to be smaller than `cap`. Depending on `realloc` this operation
             // may shrink the buffer or leave it as it is.
             ptr = match unsafe {
-                A::realloc(Some(buf.cast()), layout.into(), old_layout.into(), flags)
+                A::realloc(Some(buf.cast()), layout.into(), old_layout.into(), flags, None)
             } {
                 // If we fail to shrink, which likely can't even happen, continue with the existing
                 // buffer.
-- 
2.39.2

On Thu, Jun 26, 2025 at 10:36:53AM +0200, Vitaly Wool wrote:
> Add support for specifying NUMA ids in Rust allocators as an Option
> (i. e. providing `None` as nid corresponds to NUMA_NO_NODE). This
> will allow to specify node to use for allocation of e. g. {KV}Box.
> 
> Signed-off-by: Vitaly Wool <vitaly.wool@konsulko.se>
> ---
>  rust/helpers/slab.c            |  9 +++++----
>  rust/helpers/vmalloc.c         |  4 ++--
>  rust/kernel/alloc.rs           | 28 ++++++++++++++++++++++++++--
>  rust/kernel/alloc/allocator.rs | 26 ++++++++++++++++++--------
>  rust/kernel/alloc/kvec.rs      |  3 ++-
>  5 files changed, 53 insertions(+), 17 deletions(-)
> 
> diff --git a/rust/helpers/slab.c b/rust/helpers/slab.c
> index 5e9e8dd2bba0..ab1cf72f8353 100644
> --- a/rust/helpers/slab.c
> +++ b/rust/helpers/slab.c
> @@ -3,13 +3,14 @@
>  #include <linux/slab.h>
>  
>  void * __must_check __realloc_size(2)
> -rust_helper_krealloc(const void *objp, size_t new_size, unsigned long align, gfp_t flags)
> +rust_helper_krealloc_node(const void *objp, size_t new_size, unsigned long align, gfp_t flags,
> +			  int nid)
>  {
> -	return krealloc(objp, new_size, flags);
> +	return krealloc_node(objp, new_size, flags, nid);
>  }
>  
>  void * __must_check __realloc_size(2)
> -rust_helper_kvrealloc(const void *p, size_t size, unsigned long align, gfp_t flags)
> +rust_helper_kvrealloc_node(const void *p, size_t size, unsigned long align, gfp_t flags, int nid)
>  {
> -	return kvrealloc(p, size, flags);
> +	return kvrealloc_node(p, size, flags, nid);
>  }

Same as in the previous patch, please keep those as "normal" helpers for
*realloc_node() and create the corresponding *realloc_node_align() helpers
discarding the argument on the Rust side.

> diff --git a/rust/kernel/alloc.rs b/rust/kernel/alloc.rs
> index a2c49e5494d3..1e26c2a7f47c 100644
> --- a/rust/kernel/alloc.rs
> +++ b/rust/kernel/alloc.rs
> @@ -156,7 +156,30 @@ pub unsafe trait Allocator {
>      fn alloc(layout: Layout, flags: Flags) -> Result<NonNull<[u8]>, AllocError> {
>          // SAFETY: Passing `None` to `realloc` is valid by its safety requirements and asks for a
>          // new memory allocation.
> -        unsafe { Self::realloc(None, layout, Layout::new::<()>(), flags) }
> +        unsafe { Self::realloc(None, layout, Layout::new::<()>(), flags, None) }
> +    }
> +
> +    /// Allocate memory based on `layout`, `flags` and `nid`.
> +    ///
> +    /// On success, returns a buffer represented as `NonNull<[u8]>` that satisfies the layout
> +    /// constraints (i.e. minimum size and alignment as specified by `layout`).
> +    ///
> +    /// This function is equivalent to `realloc` when called with `None`.
> +    ///
> +    /// # Guarantees
> +    ///
> +    /// When the return value is `Ok(ptr)`, then `ptr` is
> +    /// - valid for reads and writes for `layout.size()` bytes, until it is passed to
> +    ///   [`Allocator::free`] or [`Allocator::realloc`],
> +    /// - aligned to `layout.align()`,
> +    ///
> +    /// Additionally, `Flags` are honored as documented in
> +    /// <https://docs.kernel.org/core-api/mm-api.html#mm-api-gfp-flags>.
> +    fn alloc_node(layout: Layout, flags: Flags, nid: Option<i32>)
> +                -> Result<NonNull<[u8]>, AllocError> {
> +        // SAFETY: Passing `None` to `realloc` is valid by its safety requirements and asks for a
> +        // new memory allocation.
> +        unsafe { Self::realloc(None, layout, Layout::new::<()>(), flags, nid) }
>      }
>  
>      /// Re-allocate an existing memory allocation to satisfy the requested `layout`.
> @@ -196,6 +219,7 @@ unsafe fn realloc(
>          layout: Layout,
>          old_layout: Layout,
>          flags: Flags,
> +        nid: Option<i32>,
>      ) -> Result<NonNull<[u8]>, AllocError>;

I think you did forget to add realloc_node() as requested in the last iteration.