[PATCH v5 0/4] support large align and nid in Rust allocators

[PATCH v5 0/4] support large align and nid in Rust allocators

[Vitaly Wool]

The coming patches provide the ability for Rust allocators to set
NUMA node and large alignment.

Changelog:
v2 -> v3:
* fixed the build breakage for non-MMU configs
v3 -> v4:
* added NUMA node support for k[v]realloc (patch #2)
* removed extra logic in Rust helpers
* patch for Rust allocators split into 2 (align: patch #3 and
  NUMA ids: patch #4)
v4 -> v5:
* reworked NUMA node support for k[v]realloc for all 3 <alloc>_node
  functions to have the same signature
* all 3 <alloc>_node slab/vmalloc functions now support alignment
  specification
* Rust helpers are extended with new functions, the old ones are left
  intact
* Rust support for NUMA nodes comes first now (as patch #3)
v5 -> v6:
* added <alloc>_node_align functions to keep the existing interfaces
  intact
* clearer separation for Rust support of MUNA ids and large alignments

Signed-off-by: Vitaly Wool <vitaly.wool@konsulko.se>

[PATCH v6 1/4] mm/vmalloc: allow to set node and align in vrealloc

[Vitaly Wool]

Reimplement vrealloc() to be able to set node and alignment should
a user need to do so. Rename the function to vrealloc_node_align()
to better match what it actually does now and introduce macros for
vrealloc() and friends for backward compatibility.

With that change we also provide the ability for the Rust part of
the kernel to set node and aligmnent in its allocations.

Signed-off-by: Vitaly Wool <vitaly.wool@konsulko.se>
---
 include/linux/vmalloc.h | 12 +++++++++---
 mm/vmalloc.c            | 20 ++++++++++++++++----
 2 files changed, 25 insertions(+), 7 deletions(-)

diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h
index fdc9aeb74a44..68791f7cb3ba 100644
--- a/include/linux/vmalloc.h
+++ b/include/linux/vmalloc.h
@@ -197,9 +197,15 @@ extern void *__vcalloc_noprof(size_t n, size_t size, gfp_t flags) __alloc_size(1
 extern void *vcalloc_noprof(size_t n, size_t size) __alloc_size(1, 2);
 #define vcalloc(...)		alloc_hooks(vcalloc_noprof(__VA_ARGS__))
 
-void * __must_check vrealloc_noprof(const void *p, size_t size, gfp_t flags)
-		__realloc_size(2);
-#define vrealloc(...)		alloc_hooks(vrealloc_noprof(__VA_ARGS__))
+void *__must_check vrealloc_node_align_noprof(const void *p, size_t size,
+		unsigned long align, gfp_t flags, int nid) __realloc_size(2);
+#define vrealloc_node_noprof(_p, _s, _f, _nid)	\
+	vrealloc_node_align_noprof(_p, _s, 1, _f, _nid)
+#define vrealloc_noprof(_p, _s, _f)		\
+	vrealloc_node_align_noprof(_p, _s, 1, _f, NUMA_NO_NODE)
+#define vrealloc_node_align(...)		alloc_hooks(vrealloc_node_align_noprof(__VA_ARGS__))
+#define vrealloc_node(...)			alloc_hooks(vrealloc_node_noprof(__VA_ARGS__))
+#define vrealloc(...)				alloc_hooks(vrealloc_noprof(__VA_ARGS__))
 
 extern void vfree(const void *addr);
 extern void vfree_atomic(const void *addr);
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index 6dbcdceecae1..d633ac0ff977 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -4089,12 +4089,15 @@ void *vzalloc_node_noprof(unsigned long size, int node)
 EXPORT_SYMBOL(vzalloc_node_noprof);
 
 /**
- * vrealloc - reallocate virtually contiguous memory; contents remain unchanged
+ * vrealloc_node_align_noprof - reallocate virtually contiguous memory; contents
+ * remain unchanged
  * @p: object to reallocate memory for
  * @size: the size to reallocate
+ * @align: requested alignment
  * @flags: the flags for the page level allocator
+ * @nid: node id
  *
- * If @p is %NULL, vrealloc() behaves exactly like vmalloc(). If @size is 0 and
+ * If @p is %NULL, vrealloc_XXX() behaves exactly like vmalloc(). If @size is 0 and
  * @p is not a %NULL pointer, the object pointed to is freed.
  *
  * If __GFP_ZERO logic is requested, callers must ensure that, starting with the
@@ -4111,7 +4114,8 @@ EXPORT_SYMBOL(vzalloc_node_noprof);
  * Return: pointer to the allocated memory; %NULL if @size is zero or in case of
  *         failure
  */
-void *vrealloc_noprof(const void *p, size_t size, gfp_t flags)
+void *vrealloc_node_align_noprof(const void *p, size_t size, unsigned long align,
+				 gfp_t flags, int nid)
 {
 	struct vm_struct *vm = NULL;
 	size_t alloced_size = 0;
@@ -4135,6 +4139,13 @@ void *vrealloc_noprof(const void *p, size_t size, gfp_t flags)
 		if (WARN(alloced_size < old_size,
 			 "vrealloc() has mismatched area vs requested sizes (%p)\n", p))
 			return NULL;
+		if (WARN(nid != NUMA_NO_NODE && nid != page_to_nid(vmalloc_to_page(p)),
+			 "vrealloc() has mismatched nids\n"))
+			return NULL;
+		if (WARN((uintptr_t)p & (align - 1),
+			 "will not reallocate with a bigger alignment (0x%lx)\n",
+			 align))
+			return NULL;
 	}
 
 	/*
@@ -4166,7 +4177,8 @@ void *vrealloc_noprof(const void *p, size_t size, gfp_t flags)
 	}
 
 	/* TODO: Grow the vm_area, i.e. allocate and map additional pages. */
-	n = __vmalloc_noprof(size, flags);
+	n = __vmalloc_node_noprof(size, align, flags, nid, __builtin_return_address(0));
+
 	if (!n)
 		return NULL;
 
-- 
2.39.2

[PATCH v6 2/4] mm/slab: allow to set node and align in k[v]realloc

[Vitaly Wool]

Reimplement k[v]realloc_node() to be able to set node and
alignment should a user need to do so. In order to do that while
retaining the maximal backward compatibility, add
k[v]realloc_node_align() functions and redefine the rest of API
using these new ones.

With that change we also provide the ability for the Rust part of
the kernel to set node and aligmnent in its K[v]xxx
[re]allocations.

Signed-off-by: Vitaly Wool <vitaly.wool@konsulko.se>
---
 include/linux/slab.h | 40 +++++++++++++++++++---------
 mm/nommu.c           |  3 ++-
 mm/slub.c            | 63 ++++++++++++++++++++++++++++++--------------
 3 files changed, 72 insertions(+), 34 deletions(-)

diff --git a/include/linux/slab.h b/include/linux/slab.h
index d5a8ab98035c..13abcf4ada22 100644
--- a/include/linux/slab.h
+++ b/include/linux/slab.h
@@ -465,9 +465,15 @@ int kmem_cache_shrink(struct kmem_cache *s);
 /*
  * Common kmalloc functions provided by all allocators
  */
-void * __must_check krealloc_noprof(const void *objp, size_t new_size,
-				    gfp_t flags) __realloc_size(2);
-#define krealloc(...)				alloc_hooks(krealloc_noprof(__VA_ARGS__))
+void * __must_check krealloc_node_align_noprof(const void *objp, size_t new_size,
+					       unsigned long align,
+					       gfp_t flags, int nid) __realloc_size(2);
+#define krealloc_node_noprof(_p, _s, _f, _n) \
+	krealloc_node_align_noprof(_p, _s, 1, _f, _n)
+#define krealloc_noprof(...)		krealloc_node_noprof(__VA_ARGS__, NUMA_NO_NODE)
+#define krealloc_node_align(...)	alloc_hooks(krealloc_node_align_noprof(__VA_ARGS__))
+#define krealloc_node(...)		alloc_hooks(krealloc_node_noprof(__VA_ARGS__))
+#define krealloc(...)			alloc_hooks(krealloc_noprof(__VA_ARGS__))
 
 void kfree(const void *objp);
 void kfree_sensitive(const void *objp);
@@ -1041,18 +1047,23 @@ static inline __alloc_size(1) void *kzalloc_noprof(size_t size, gfp_t flags)
 #define kzalloc(...)				alloc_hooks(kzalloc_noprof(__VA_ARGS__))
 #define kzalloc_node(_size, _flags, _node)	kmalloc_node(_size, (_flags)|__GFP_ZERO, _node)
 
-void *__kvmalloc_node_noprof(DECL_BUCKET_PARAMS(size, b), gfp_t flags, int node) __alloc_size(1);
-#define kvmalloc_node_noprof(size, flags, node)	\
-	__kvmalloc_node_noprof(PASS_BUCKET_PARAMS(size, NULL), flags, node)
+void *__kvmalloc_node_noprof(DECL_BUCKET_PARAMS(size, b), unsigned long align,
+			     gfp_t flags, int node) __alloc_size(1);
+#define kvmalloc_node_align_noprof(_size, _align, _flags, _node)	\
+	__kvmalloc_node_noprof(PASS_BUCKET_PARAMS(_size, NULL), _align, _flags, _node)
+#define kvmalloc_node_noprof(_size, _flags, _node)	\
+	kvmalloc_node_align_noprof(_size, 1, _flags, _node)
+#define kvmalloc_node_align(...)		\
+	alloc_hooks(kvmalloc_node_align_noprof(__VA_ARGS__))
 #define kvmalloc_node(...)			alloc_hooks(kvmalloc_node_noprof(__VA_ARGS__))
 
-#define kvmalloc(_size, _flags)			kvmalloc_node(_size, _flags, NUMA_NO_NODE)
-#define kvmalloc_noprof(_size, _flags)		kvmalloc_node_noprof(_size, _flags, NUMA_NO_NODE)
+#define kvmalloc_noprof(...)			kvmalloc_node_noprof(__VA_ARGS__, NUMA_NO_NODE)
+#define kvmalloc(...)				alloc_hooks(kvmalloc_noprof(__VA_ARGS__))
 #define kvzalloc(_size, _flags)			kvmalloc(_size, (_flags)|__GFP_ZERO)
 
-#define kvzalloc_node(_size, _flags, _node)	kvmalloc_node(_size, (_flags)|__GFP_ZERO, _node)
+#define kvzalloc_node(_s, _f, _n)		kvmalloc_node(_s, (_f)|__GFP_ZERO, _n)
 #define kmem_buckets_valloc(_b, _size, _flags)	\
-	alloc_hooks(__kvmalloc_node_noprof(PASS_BUCKET_PARAMS(_size, _b), _flags, NUMA_NO_NODE))
+	alloc_hooks(__kvmalloc_node_noprof(PASS_BUCKET_PARAMS(_size, _b), 1, _flags, NUMA_NO_NODE))
 
 static inline __alloc_size(1, 2) void *
 kvmalloc_array_node_noprof(size_t n, size_t size, gfp_t flags, int node)
@@ -1068,13 +1079,16 @@ kvmalloc_array_node_noprof(size_t n, size_t size, gfp_t flags, int node)
 #define kvmalloc_array_noprof(...)		kvmalloc_array_node_noprof(__VA_ARGS__, NUMA_NO_NODE)
 #define kvcalloc_node_noprof(_n,_s,_f,_node)	kvmalloc_array_node_noprof(_n,_s,(_f)|__GFP_ZERO,_node)
 #define kvcalloc_noprof(...)			kvcalloc_node_noprof(__VA_ARGS__, NUMA_NO_NODE)
-
 #define kvmalloc_array(...)			alloc_hooks(kvmalloc_array_noprof(__VA_ARGS__))
 #define kvcalloc_node(...)			alloc_hooks(kvcalloc_node_noprof(__VA_ARGS__))
 #define kvcalloc(...)				alloc_hooks(kvcalloc_noprof(__VA_ARGS__))
 
-void *kvrealloc_noprof(const void *p, size_t size, gfp_t flags)
-		__realloc_size(2);
+void *kvrealloc_node_align_noprof(const void *p, size_t size, unsigned long align,
+				  gfp_t flags, int nid) __realloc_size(2);
+#define kvrealloc_node_align(...)		kvrealloc_node_align_noprof(__VA_ARGS__)
+#define kvrealloc_node_noprof(_p, _s, _f, _n)	kvrealloc_node_align_noprof(_p, _s, 1, _f, _n)
+#define kvrealloc_node(...)			alloc_hooks(kvrealloc_node_noprof(__VA_ARGS__))
+#define kvrealloc_noprof(...)			kvrealloc_node_noprof(__VA_ARGS__, NUMA_NO_NODE)
 #define kvrealloc(...)				alloc_hooks(kvrealloc_noprof(__VA_ARGS__))
 
 extern void kvfree(const void *addr);
diff --git a/mm/nommu.c b/mm/nommu.c
index 87e1acab0d64..8359b2025b9f 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -119,7 +119,8 @@ void *__vmalloc_noprof(unsigned long size, gfp_t gfp_mask)
 }
 EXPORT_SYMBOL(__vmalloc_noprof);
 
-void *vrealloc_noprof(const void *p, size_t size, gfp_t flags)
+void *vrealloc_node_align_noprof(const void *p, size_t size, unsigned long align,
+				 gfp_t flags, int node)
 {
 	return krealloc_noprof(p, size, (flags | __GFP_COMP) & ~__GFP_HIGHMEM);
 }
diff --git a/mm/slub.c b/mm/slub.c
index c4b64821e680..ec355ce31965 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -4845,7 +4845,7 @@ void kfree(const void *object)
 EXPORT_SYMBOL(kfree);
 
 static __always_inline __realloc_size(2) void *
-__do_krealloc(const void *p, size_t new_size, gfp_t flags)
+__do_krealloc(const void *p, size_t new_size, unsigned long align, gfp_t flags, int nid)
 {
 	void *ret;
 	size_t ks = 0;
@@ -4859,6 +4859,19 @@ __do_krealloc(const void *p, size_t new_size, gfp_t flags)
 	if (!kasan_check_byte(p))
 		return NULL;
 
+	/* refuse to proceed if alignment is bigger than what kmalloc() provides */
+	if (((uintptr_t)p & (align - 1)) || new_size < align)
+		return NULL;
+
+	/*
+	 * it is possible to support reallocation with a different nid, but
+	 * it doesn't go well with the concept of krealloc(). Such
+	 * reallocation should be done explicitly instead.
+	 */
+	if (WARN(nid != NUMA_NO_NODE && nid != page_to_nid(virt_to_page(p)),
+				"krealloc() has mismatched nids\n"))
+		return NULL;
+
 	if (is_kfence_address(p)) {
 		ks = orig_size = kfence_ksize(p);
 	} else {
@@ -4903,7 +4916,7 @@ __do_krealloc(const void *p, size_t new_size, gfp_t flags)
 	return (void *)p;
 
 alloc_new:
-	ret = kmalloc_node_track_caller_noprof(new_size, flags, NUMA_NO_NODE, _RET_IP_);
+	ret = kmalloc_node_track_caller_noprof(new_size, flags, nid, _RET_IP_);
 	if (ret && p) {
 		/* Disable KASAN checks as the object's redzone is accessed. */
 		kasan_disable_current();
@@ -4915,10 +4928,12 @@ __do_krealloc(const void *p, size_t new_size, gfp_t flags)
 }
 
 /**
- * krealloc - reallocate memory. The contents will remain unchanged.
+ * krealloc_node_align - reallocate memory. The contents will remain unchanged.
  * @p: object to reallocate memory for.
  * @new_size: how many bytes of memory are required.
+ * @align: desired alignment.
  * @flags: the type of memory to allocate.
+ * @nid: NUMA node or NUMA_NO_NODE
  *
  * If @p is %NULL, krealloc() behaves exactly like kmalloc().  If @new_size
  * is 0 and @p is not a %NULL pointer, the object pointed to is freed.
@@ -4947,7 +4962,8 @@ __do_krealloc(const void *p, size_t new_size, gfp_t flags)
  *
  * Return: pointer to the allocated memory or %NULL in case of error
  */
-void *krealloc_noprof(const void *p, size_t new_size, gfp_t flags)
+void *krealloc_node_align_noprof(const void *p, size_t new_size, unsigned long align,
+				 gfp_t flags, int nid)
 {
 	void *ret;
 
@@ -4956,13 +4972,13 @@ void *krealloc_noprof(const void *p, size_t new_size, gfp_t flags)
 		return ZERO_SIZE_PTR;
 	}
 
-	ret = __do_krealloc(p, new_size, flags);
+	ret = __do_krealloc(p, new_size, align, flags, nid);
 	if (ret && kasan_reset_tag(p) != kasan_reset_tag(ret))
 		kfree(p);
 
 	return ret;
 }
-EXPORT_SYMBOL(krealloc_noprof);
+EXPORT_SYMBOL(krealloc_node_align_noprof);
 
 static gfp_t kmalloc_gfp_adjust(gfp_t flags, size_t size)
 {
@@ -4993,6 +5009,7 @@ static gfp_t kmalloc_gfp_adjust(gfp_t flags, size_t size)
  * failure, fall back to non-contiguous (vmalloc) allocation.
  * @size: size of the request.
  * @b: which set of kmalloc buckets to allocate from.
+ * @align: desired alignment.
  * @flags: gfp mask for the allocation - must be compatible (superset) with GFP_KERNEL.
  * @node: numa node to allocate from
  *
@@ -5005,19 +5022,22 @@ static gfp_t kmalloc_gfp_adjust(gfp_t flags, size_t size)
  *
  * Return: pointer to the allocated memory of %NULL in case of failure
  */
-void *__kvmalloc_node_noprof(DECL_BUCKET_PARAMS(size, b), gfp_t flags, int node)
+void *__kvmalloc_node_noprof(DECL_BUCKET_PARAMS(size, b), unsigned long align,
+			     gfp_t flags, int node)
 {
 	void *ret;
 
 	/*
 	 * It doesn't really make sense to fallback to vmalloc for sub page
-	 * requests
+	 * requests and small alignments
 	 */
-	ret = __do_kmalloc_node(size, PASS_BUCKET_PARAM(b),
-				kmalloc_gfp_adjust(flags, size),
-				node, _RET_IP_);
-	if (ret || size <= PAGE_SIZE)
-		return ret;
+	if (size >= align) {
+		ret = __do_kmalloc_node(size, PASS_BUCKET_PARAM(b),
+					kmalloc_gfp_adjust(flags, size),
+					node, _RET_IP_);
+		if (ret || size <= PAGE_SIZE)
+			return ret;
+	}
 
 	/* non-sleeping allocations are not supported by vmalloc */
 	if (!gfpflags_allow_blocking(flags))
@@ -5035,7 +5055,7 @@ void *__kvmalloc_node_noprof(DECL_BUCKET_PARAMS(size, b), gfp_t flags, int node)
 	 * about the resulting pointer, and cannot play
 	 * protection games.
 	 */
-	return __vmalloc_node_range_noprof(size, 1, VMALLOC_START, VMALLOC_END,
+	return __vmalloc_node_range_noprof(size, align, VMALLOC_START, VMALLOC_END,
 			flags, PAGE_KERNEL, VM_ALLOW_HUGE_VMAP,
 			node, __builtin_return_address(0));
 }
@@ -5079,10 +5099,12 @@ void kvfree_sensitive(const void *addr, size_t len)
 EXPORT_SYMBOL(kvfree_sensitive);
 
 /**
- * kvrealloc - reallocate memory; contents remain unchanged
+ * kvrealloc_node_align - reallocate memory; contents remain unchanged
  * @p: object to reallocate memory for
  * @size: the size to reallocate
+ * @align: desired alignment
  * @flags: the flags for the page level allocator
+ * @nid: NUMA node id
  *
  * If @p is %NULL, kvrealloc() behaves exactly like kvmalloc(). If @size is 0
  * and @p is not a %NULL pointer, the object pointed to is freed.
@@ -5100,17 +5122,18 @@ EXPORT_SYMBOL(kvfree_sensitive);
  *
  * Return: pointer to the allocated memory or %NULL in case of error
  */
-void *kvrealloc_noprof(const void *p, size_t size, gfp_t flags)
+void *kvrealloc_node_align_noprof(const void *p, size_t size, unsigned long align,
+				  gfp_t flags, int nid)
 {
 	void *n;
 
 	if (is_vmalloc_addr(p))
-		return vrealloc_noprof(p, size, flags);
+		return vrealloc_node_align_noprof(p, size, align, flags, nid);
 
-	n = krealloc_noprof(p, size, kmalloc_gfp_adjust(flags, size));
+	n = krealloc_node_align_noprof(p, size, align, kmalloc_gfp_adjust(flags, size), nid);
 	if (!n) {
 		/* We failed to krealloc(), fall back to kvmalloc(). */
-		n = kvmalloc_noprof(size, flags);
+		n = kvmalloc_node_align_noprof(size, align, flags, nid);
 		if (!n)
 			return NULL;
 
@@ -5126,7 +5149,7 @@ void *kvrealloc_noprof(const void *p, size_t size, gfp_t flags)
 
 	return n;
 }
-EXPORT_SYMBOL(kvrealloc_noprof);
+EXPORT_SYMBOL(kvrealloc_node_align_noprof);
 
 struct detached_freelist {
 	struct slab *slab;
-- 
2.39.2

[PATCH v6 3/4] rust: add support for NUMA ids in allocations

[Vitaly Wool]

Add support for specifying NUMA ids in Rust allocators as an Option
(i. e. providing `None` as nid corresponds to NUMA_NO_NODE). To do
this, modify ReallocFunc to use the new extended realloc primitives
from the C side of the kernel (i. e. k[v]realloc_node/vrealloc_node)
and add the new function alloc_node to the Allocator trait while
keeping the existing one (alloc) for backward compatibility.

This will allow to specify node to use for allocation of e. g.
{KV}Box, as well as for future NUMA aware users of the API.

Signed-off-by: Vitaly Wool <vitaly.wool@konsulko.se>
---
 rust/helpers/slab.c            | 12 ++++++++++++
 rust/helpers/vmalloc.c         |  6 ++++++
 rust/kernel/alloc.rs           | 28 ++++++++++++++++++++++++++--
 rust/kernel/alloc/allocator.rs | 33 ++++++++++++++++++++++-----------
 rust/kernel/alloc/kvec.rs      |  3 ++-
 5 files changed, 68 insertions(+), 14 deletions(-)

diff --git a/rust/helpers/slab.c b/rust/helpers/slab.c
index a842bfbddcba..5abd552ccbd4 100644
--- a/rust/helpers/slab.c
+++ b/rust/helpers/slab.c
@@ -13,3 +13,15 @@ rust_helper_kvrealloc(const void *p, size_t size, gfp_t flags)
 {
 	return kvrealloc(p, size, flags);
 }
+
+void * __must_check __realloc_size(2)
+rust_helper_krealloc_node(const void *objp, size_t new_size, gfp_t flags, int node)
+{
+	return krealloc_node(objp, new_size, flags, node);
+}
+
+void * __must_check __realloc_size(2)
+rust_helper_kvrealloc_node(const void *p, size_t size, gfp_t flags, int node)
+{
+	return kvrealloc_node(p, size, flags, node);
+}
diff --git a/rust/helpers/vmalloc.c b/rust/helpers/vmalloc.c
index 80d34501bbc0..e6c796c65ee1 100644
--- a/rust/helpers/vmalloc.c
+++ b/rust/helpers/vmalloc.c
@@ -7,3 +7,9 @@ rust_helper_vrealloc(const void *p, size_t size, gfp_t flags)
 {
 	return vrealloc(p, size, flags);
 }
+
+void * __must_check __realloc_size(2)
+rust_helper_vrealloc_node(const void *p, size_t size, gfp_t flags, int node)
+{
+	return vrealloc_node(p, size, 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 aa2dfa9dca4c..47d9668c3599 100644
--- a/rust/kernel/alloc/allocator.rs
+++ b/rust/kernel/alloc/allocator.rs
@@ -58,18 +58,20 @@ 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, u32) -> *mut crate::ffi::c_void,
+    unsafe extern "C" fn(
+        *const crate::ffi::c_void, usize, u32, crate::ffi::c_int
+    ) -> *mut crate::ffi::c_void,
 );
 
 impl ReallocFunc {
-    // INVARIANT: `krealloc` satisfies the type invariants.
-    const KREALLOC: Self = Self(bindings::krealloc);
+    // INVARIANT: `krealloc_node` satisfies the type invariants.
+    const KREALLOC_NODE: Self = Self(bindings::krealloc_node);
 
-    // INVARIANT: `vrealloc` satisfies the type invariants.
-    const VREALLOC: Self = Self(bindings::vrealloc);
+    // INVARIANT: `vrealloc_node` satisfies the type invariants.
+    const VREALLOC_NODE: Self = Self(bindings::vrealloc_node);
 
-    // INVARIANT: `kvrealloc` satisfies the type invariants.
-    const KVREALLOC: Self = Self(bindings::kvrealloc);
+    // INVARIANT: `kvrealloc_node` satisfies the type invariants.
+    const KVREALLOC_NODE: Self = Self(bindings::kvrealloc_node);
 
     /// # Safety
     ///
@@ -87,6 +89,7 @@ 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 +103,11 @@ 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 +118,7 @@ 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, flags.0).cast()
+            self.0(ptr.cast(), size, flags.0, c_nid).cast()
         };
 
         let ptr = if size == 0 {
@@ -134,9 +142,10 @@ 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_NODE.call(ptr, layout, old_layout, flags, nid) }
     }
 }
 
@@ -151,6 +160,7 @@ unsafe fn realloc(
         layout: Layout,
         old_layout: Layout,
         flags: Flags,
+        nid: Option<i32>,
     ) -> Result<NonNull<[u8]>, AllocError> {
         // TODO: Support alignments larger than PAGE_SIZE.
         if layout.align() > bindings::PAGE_SIZE {
@@ -160,7 +170,7 @@ unsafe fn realloc(
 
         // 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_NODE.call(ptr, layout, old_layout, flags, nid) }
     }
 }
 
@@ -175,6 +185,7 @@ unsafe fn realloc(
         layout: Layout,
         old_layout: Layout,
         flags: Flags,
+        nid: Option<i32>,
     ) -> Result<NonNull<[u8]>, AllocError> {
         // TODO: Support alignments larger than PAGE_SIZE.
         if layout.align() > bindings::PAGE_SIZE {
@@ -184,6 +195,6 @@ unsafe fn realloc(
 
         // 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_NODE.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

[PATCH v6 4/4] rust: support large alignments in allocations

[Vitaly Wool]

Add support for large (> PAGE_SIZE) alignments in Rust allocators.
All the preparations on the C side are already done, we just need
to add bindings for <alloc>_node_align() functions and start
using those.

Signed-off-by: Vitaly Wool <vitaly.wool@konsulko.se>
---
 rust/helpers/slab.c            | 14 ++++++++++++++
 rust/helpers/vmalloc.c         |  7 +++++++
 rust/kernel/alloc/allocator.rs | 34 +++++++++++-----------------------
 3 files changed, 32 insertions(+), 23 deletions(-)

diff --git a/rust/helpers/slab.c b/rust/helpers/slab.c
index 5abd552ccbd4..c4bb451bcf4e 100644
--- a/rust/helpers/slab.c
+++ b/rust/helpers/slab.c
@@ -25,3 +25,17 @@ rust_helper_kvrealloc_node(const void *p, size_t size, gfp_t flags, int node)
 {
 	return kvrealloc_node(p, size, flags, node);
 }
+
+void * __must_check __realloc_size(2)
+rust_helper_krealloc_node_align(const void *objp, size_t new_size, unsigned long align,
+				gfp_t flags, int node)
+{
+	return krealloc_node_align(objp, new_size, align, flags, node);
+}
+
+void * __must_check __realloc_size(2)
+rust_helper_kvrealloc_node_align(const void *p, size_t size, unsigned long align,
+				gfp_t flags, int node)
+{
+	return kvrealloc_node_align(p, size, align, flags, node);
+}
diff --git a/rust/helpers/vmalloc.c b/rust/helpers/vmalloc.c
index e6c796c65ee1..09aee472340f 100644
--- a/rust/helpers/vmalloc.c
+++ b/rust/helpers/vmalloc.c
@@ -13,3 +13,10 @@ rust_helper_vrealloc_node(const void *p, size_t size, gfp_t flags, int node)
 {
 	return vrealloc_node(p, size, flags, node);
 }
+
+void * __must_check __realloc_size(2)
+rust_helper_vrealloc_node_align(const void *p, size_t size, unsigned long align,
+				gfp_t flags, int node)
+{
+	return vrealloc_node_align(p, size, align, flags, node);
+}
diff --git a/rust/kernel/alloc/allocator.rs b/rust/kernel/alloc/allocator.rs
index 47d9668c3599..7f986c974150 100644
--- a/rust/kernel/alloc/allocator.rs
+++ b/rust/kernel/alloc/allocator.rs
@@ -59,19 +59,19 @@ 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, u32, crate::ffi::c_int
+        *const crate::ffi::c_void, usize, crate::ffi::c_ulong, u32, crate::ffi::c_int,
     ) -> *mut crate::ffi::c_void,
 );
 
 impl ReallocFunc {
-    // INVARIANT: `krealloc_node` satisfies the type invariants.
-    const KREALLOC_NODE: Self = Self(bindings::krealloc_node);
+    // INVARIANT: `krealloc_node_align` satisfies the type invariants.
+    const KREALLOC_NODE_ALIGN: Self = Self(bindings::krealloc_node_align);
 
-    // INVARIANT: `vrealloc_node` satisfies the type invariants.
-    const VREALLOC_NODE: Self = Self(bindings::vrealloc_node);
+    // INVARIANT: `vrealloc_node_align` satisfies the type invariants.
+    const VREALLOC_NODE_ALIGN: Self = Self(bindings::vrealloc_node_align);
 
-    // INVARIANT: `kvrealloc_node` satisfies the type invariants.
-    const KVREALLOC_NODE: Self = Self(bindings::kvrealloc_node);
+    // INVARIANT: `kvrealloc_node_align` satisfies the type invariants.
+    const KVREALLOC_NODE_ALIGN: Self = Self(bindings::kvrealloc_node_align);
 
     /// # Safety
     ///
@@ -118,7 +118,7 @@ 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, flags.0, c_nid).cast()
+            self.0(ptr.cast(), size, layout.align(), flags.0, c_nid).cast()
         };
 
         let ptr = if size == 0 {
@@ -145,7 +145,7 @@ unsafe fn realloc(
         nid: Option<i32>,
     ) -> Result<NonNull<[u8]>, AllocError> {
         // SAFETY: `ReallocFunc::call` has the same safety requirements as `Allocator::realloc`.
-        unsafe { ReallocFunc::KREALLOC_NODE.call(ptr, layout, old_layout, flags, nid) }
+        unsafe { ReallocFunc::KREALLOC_NODE_ALIGN.call(ptr, layout, old_layout, flags, nid) }
     }
 }
 
@@ -162,15 +162,9 @@ unsafe fn realloc(
         flags: Flags,
         nid: Option<i32>,
     ) -> Result<NonNull<[u8]>, AllocError> {
-        // TODO: Support alignments larger than PAGE_SIZE.
-        if layout.align() > bindings::PAGE_SIZE {
-            pr_warn!("Vmalloc does not support alignments larger than PAGE_SIZE yet.\n");
-            return Err(AllocError);
-        }
-
         // SAFETY: If not `None`, `ptr` is guaranteed to point to valid memory, which was previously
         // allocated with this `Allocator`.
-        unsafe { ReallocFunc::VREALLOC_NODE.call(ptr, layout, old_layout, flags, nid) }
+        unsafe { ReallocFunc::VREALLOC_NODE_ALIGN.call(ptr, layout, old_layout, flags, nid) }
     }
 }
 
@@ -187,14 +181,8 @@ unsafe fn realloc(
         flags: Flags,
         nid: Option<i32>,
     ) -> Result<NonNull<[u8]>, AllocError> {
-        // TODO: Support alignments larger than PAGE_SIZE.
-        if layout.align() > bindings::PAGE_SIZE {
-            pr_warn!("KVmalloc does not support alignments larger than PAGE_SIZE yet.\n");
-            return Err(AllocError);
-        }
-
         // SAFETY: If not `None`, `ptr` is guaranteed to point to valid memory, which was previously
         // allocated with this `Allocator`.
-        unsafe { ReallocFunc::KVREALLOC_NODE.call(ptr, layout, old_layout, flags, nid) }
+        unsafe { ReallocFunc::KVREALLOC_NODE_ALIGN.call(ptr, layout, old_layout, flags, nid) }
     }
 }
-- 
2.39.2

Re: [PATCH v6 3/4] rust: add support for NUMA ids in allocations

[Danilo Krummrich]

On Fri, Jun 27, 2025 at 08:16:38PM +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). To do
> this, modify ReallocFunc to use the new extended realloc primitives
> from the C side of the kernel (i. e. k[v]realloc_node/vrealloc_node)
> and add the new function alloc_node to the Allocator trait while
> keeping the existing one (alloc) for backward compatibility.
> 
> This will allow to specify node to use for allocation of e. g.
> {KV}Box, as well as for future NUMA aware users of the API.
> 
> Signed-off-by: Vitaly Wool <vitaly.wool@konsulko.se>

Did you see [1]? I can't see the feedback being addressed.

[1] https://lore.kernel.org/lkml/aF5-a-bUp1pD5tiS@pollux/

Re: [PATCH v6 4/4] rust: support large alignments in allocations

[Danilo Krummrich]

On Fri, Jun 27, 2025 at 08:16:50PM +0200, Vitaly Wool wrote:
> Add support for large (> PAGE_SIZE) alignments in Rust allocators.
> All the preparations on the C side are already done, we just need
> to add bindings for <alloc>_node_align() functions and start
> using those.
> 
> Signed-off-by: Vitaly Wool <vitaly.wool@konsulko.se>
> ---
>  rust/helpers/slab.c            | 14 ++++++++++++++
>  rust/helpers/vmalloc.c         |  7 +++++++
>  rust/kernel/alloc/allocator.rs | 34 +++++++++++-----------------------
>  3 files changed, 32 insertions(+), 23 deletions(-)
> 
> diff --git a/rust/helpers/slab.c b/rust/helpers/slab.c
> index 5abd552ccbd4..c4bb451bcf4e 100644
> --- a/rust/helpers/slab.c
> +++ b/rust/helpers/slab.c
> @@ -25,3 +25,17 @@ rust_helper_kvrealloc_node(const void *p, size_t size, gfp_t flags, int node)
>  {
>  	return kvrealloc_node(p, size, flags, node);
>  }
> +
> +void * __must_check __realloc_size(2)
> +rust_helper_krealloc_node_align(const void *objp, size_t new_size, unsigned long align,
> +				gfp_t flags, int node)
> +{
> +	return krealloc_node_align(objp, new_size, align, flags, node);
> +}
> +
> +void * __must_check __realloc_size(2)
> +rust_helper_kvrealloc_node_align(const void *p, size_t size, unsigned long align,
> +				gfp_t flags, int node)
> +{
> +	return kvrealloc_node_align(p, size, align, flags, node);
> +}
> diff --git a/rust/helpers/vmalloc.c b/rust/helpers/vmalloc.c
> index e6c796c65ee1..09aee472340f 100644
> --- a/rust/helpers/vmalloc.c
> +++ b/rust/helpers/vmalloc.c
> @@ -13,3 +13,10 @@ rust_helper_vrealloc_node(const void *p, size_t size, gfp_t flags, int node)
>  {
>  	return vrealloc_node(p, size, flags, node);
>  }
> +
> +void * __must_check __realloc_size(2)
> +rust_helper_vrealloc_node_align(const void *p, size_t size, unsigned long align,
> +				gfp_t flags, int node)
> +{
> +	return vrealloc_node_align(p, size, align, flags, node);
> +}

Here and in the previous patch, please remove unused helper functions when you
replace their usage with new ones.

Thanks,
Danilo

Re: [PATCH v6 3/4] rust: add support for NUMA ids in allocations

[Vitaly Wool]

> On Jun 27, 2025, at 8:36 PM, Danilo Krummrich <dakr@kernel.org> wrote:
> 
> On Fri, Jun 27, 2025 at 08:16:38PM +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). To do
>> this, modify ReallocFunc to use the new extended realloc primitives
>> from the C side of the kernel (i. e. k[v]realloc_node/vrealloc_node)
>> and add the new function alloc_node to the Allocator trait while
>> keeping the existing one (alloc) for backward compatibility.
>> 
>> This will allow to specify node to use for allocation of e. g.
>> {KV}Box, as well as for future NUMA aware users of the API.
>> 
>> Signed-off-by: Vitaly Wool <vitaly.wool@konsulko.se>
> 
> Did you see [1]? I can't see the feedback being addressed.
> 
> [1] https://lore.kernel.org/lkml/aF5-a-bUp1pD5tiS@pollux/

Awkwardly enough, this one I did miss.