diff mbox series

[v3,07/25] rust: alloc: implement `KVmalloc` allocator

Message ID 20240801000641.1882-8-dakr@kernel.org (mailing list archive)
State New
Headers show
Series Generic `Allocator` support for Rust | expand

Commit Message

Danilo Krummrich Aug. 1, 2024, 12:02 a.m. UTC 
Implement `Allocator` for `KVmalloc`, an `Allocator` that tries to
allocate memory wth `kmalloc` first and, on failure, falls back to
`vmalloc`.

All memory allocations made with `KVmalloc` end up in
`kvrealloc_noprof()`; all frees in `kvfree()`.

Signed-off-by: Danilo Krummrich <dakr@kernel.org>
---
 rust/helpers.c                      |  7 +++++++
 rust/kernel/alloc/allocator.rs      | 24 ++++++++++++++++++++++++
 rust/kernel/alloc/allocator_test.rs |  1 +
 3 files changed, 32 insertions(+)

Comments

Alice Ryhl Aug. 1, 2024, 8:43 a.m. UTC | #1 
On Thu, Aug 1, 2024 at 2:07 AM Danilo Krummrich <dakr@kernel.org> wrote:
>
> Implement `Allocator` for `KVmalloc`, an `Allocator` that tries to
> allocate memory wth `kmalloc` first and, on failure, falls back to
> `vmalloc`.
>
> All memory allocations made with `KVmalloc` end up in
> `kvrealloc_noprof()`; all frees in `kvfree()`.
>
> Signed-off-by: Danilo Krummrich <dakr@kernel.org>

The nit from vrealloc also applies here, but:

Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Danilo Krummrich Aug. 1, 2024, 12:31 p.m. UTC | #2 
On Thu, Aug 01, 2024 at 10:43:44AM +0200, Alice Ryhl wrote:
> On Thu, Aug 1, 2024 at 2:07 AM Danilo Krummrich <dakr@kernel.org> wrote:
> >
> > Implement `Allocator` for `KVmalloc`, an `Allocator` that tries to
> > allocate memory wth `kmalloc` first and, on failure, falls back to
> > `vmalloc`.
> >
> > All memory allocations made with `KVmalloc` end up in
> > `kvrealloc_noprof()`; all frees in `kvfree()`.
> >
> > Signed-off-by: Danilo Krummrich <dakr@kernel.org>
> 
> The nit from vrealloc also applies here, but:

Yes, I will add the invariant comment for both.

> 
> Reviewed-by: Alice Ryhl <aliceryhl@google.com>
>
diff mbox series

Patch

diff --git a/rust/helpers.c b/rust/helpers.c
index 4c628986f0c9..4ad7dc347523 100644
--- a/rust/helpers.c
+++ b/rust/helpers.c
@@ -208,6 +208,13 @@  rust_helper_vrealloc(const void *p, size_t size, gfp_t flags)
 }
 EXPORT_SYMBOL_GPL(rust_helper_vrealloc);
 
+void * __must_check __realloc_size(2)
+rust_helper_kvrealloc(const void *p, size_t size, gfp_t flags)
+{
+	return kvrealloc(p, size, flags);
+}
+EXPORT_SYMBOL_GPL(rust_helper_kvrealloc);
+
 /*
  * `bindgen` binds the C `size_t` type as the Rust `usize` type, so we can
  * use it in contexts where Rust expects a `usize` like slice (array) indices.
diff --git a/rust/kernel/alloc/allocator.rs b/rust/kernel/alloc/allocator.rs
index e9a3d0694f41..1e53f149db96 100644
--- a/rust/kernel/alloc/allocator.rs
+++ b/rust/kernel/alloc/allocator.rs
@@ -22,6 +22,12 @@ 
 /// contiguous kernel virtual space.
 pub struct Vmalloc;
 
+/// The kvmalloc kernel allocator.
+///
+/// Attempt to allocate physically contiguous memory, but upon failure, fall back to non-contiguous
+/// (vmalloc) allocation.
+pub struct KVmalloc;
+
 /// Returns a proper size to alloc a new object aligned to `new_layout`'s alignment.
 fn aligned_size(new_layout: Layout) -> usize {
     // Customized layouts from `Layout::from_size_align()` can have size < align, so pad first.
@@ -68,6 +74,10 @@  fn vrealloc() -> Self {
         Self(bindings::vrealloc)
     }
 
+    fn kvrealloc() -> Self {
+        Self(bindings::kvrealloc)
+    }
+
     // SAFETY: `call` has the exact same safety requirements as `Allocator::realloc`.
     unsafe fn call(
         &self,
@@ -160,6 +170,20 @@  unsafe fn realloc(
     }
 }
 
+unsafe impl Allocator for KVmalloc {
+    unsafe fn realloc(
+        ptr: Option<NonNull<u8>>,
+        layout: Layout,
+        flags: Flags,
+    ) -> Result<NonNull<[u8]>, AllocError> {
+        let realloc = ReallocFunc::kvrealloc();
+
+        // SAFETY: If not `None`, `ptr` is guaranteed to point to valid memory, which was previously
+        // allocated with this `Allocator`.
+        unsafe { realloc.call(ptr, layout, flags) }
+    }
+}
+
 #[global_allocator]
 static ALLOCATOR: Kmalloc = Kmalloc;
 
diff --git a/rust/kernel/alloc/allocator_test.rs b/rust/kernel/alloc/allocator_test.rs
index e7bf2982f68f..1b2642c547ec 100644
--- a/rust/kernel/alloc/allocator_test.rs
+++ b/rust/kernel/alloc/allocator_test.rs
@@ -8,6 +8,7 @@ 
 
 pub struct Kmalloc;
 pub type Vmalloc = Kmalloc;
+pub type KVmalloc = Kmalloc;
 
 unsafe impl Allocator for Kmalloc {
     unsafe fn realloc(