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Message-ID: <CAJ-ks9mB8tAG+vE2RnN0+3-pqcQU_KkmZUHU++-uswpxLBp9Kg@mail.gmail.com>
Date: Thu, 26 Jun 2025 13:53:03 -0700
From: Tamir Duberstein <tamird@...il.com>
To: Vitaly Wool <vitaly.wool@...sulko.se>
Cc: linux-mm@...ck.org, akpm@...ux-foundation.org,
linux-kernel@...r.kernel.org, Uladzislau Rezki <urezki@...il.com>,
Danilo Krummrich <dakr@...nel.org>, Alice Ryhl <aliceryhl@...gle.com>, rust-for-linux@...r.kernel.org
Subject: Re: [PATCH v4 2/4] mm/slub: allow to set node and align in k[v]realloc
On Thu, Jun 26, 2025 at 1:39 AM Vitaly Wool <vitaly.wool@...sulko.se> wrote:
>
> Reimplement k[v]realloc() to be able to set node and alignment
> should a user need to do so. Rename the respective functions to
> k[v]realloc_node() to better match what they actually do now and
> introduce macros for k[v]realloc() 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 K[v]xxx [re]allocations.
>
> Signed-off-by: Vitaly Wool <vitaly.wool@...sulko.se>
Hi Vitaly, there is a typo in the subject line: it should be slab, not slub.
> ---
> include/linux/slab.h | 12 ++++++++----
> mm/slub.c | 33 ++++++++++++++++++++++-----------
> 2 files changed, 30 insertions(+), 15 deletions(-)
>
> diff --git a/include/linux/slab.h b/include/linux/slab.h
> index d5a8ab98035c..119f100978c8 100644
> --- a/include/linux/slab.h
> +++ b/include/linux/slab.h
> @@ -465,9 +465,11 @@ 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_noprof(const void *objp, size_t new_size,
> + gfp_t flags, int nid) __realloc_size(2);
> +#define krealloc_node(...) alloc_hooks(krealloc_node_noprof(__VA_ARGS__))
> +#define krealloc_noprof(o, s, f) krealloc_node_noprof(o, s, f, NUMA_NO_NODE)
> +#define krealloc(...) alloc_hooks(krealloc_noprof(__VA_ARGS__))
>
> void kfree(const void *objp);
> void kfree_sensitive(const void *objp);
> @@ -1073,8 +1075,10 @@ kvmalloc_array_node_noprof(size_t n, size_t size, gfp_t flags, int node)
> #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)
> +void *kvrealloc_node_noprof(const void *p, size_t size, gfp_t flags, int nid)
> __realloc_size(2);
> +#define kvrealloc_node(...) alloc_hooks(kvrealloc_node_noprof(__VA_ARGS__))
> +#define kvrealloc_noprof(p, s, f) kvrealloc_node_noprof(p, s, f, NUMA_NO_NODE)
> #define kvrealloc(...) alloc_hooks(kvrealloc_noprof(__VA_ARGS__))
>
> extern void kvfree(const void *addr);
> diff --git a/mm/slub.c b/mm/slub.c
> index c4b64821e680..2d5150d075d5 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, gfp_t flags, int nid)
> {
> void *ret;
> size_t ks = 0;
> @@ -4859,6 +4859,15 @@ __do_krealloc(const void *p, size_t new_size, gfp_t flags)
> if (!kasan_check_byte(p))
> 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 +4912,7 @@ __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();
> @@ -4919,6 +4928,7 @@ __do_krealloc(const void *p, size_t new_size, gfp_t flags)
> * @p: object to reallocate memory for.
> * @new_size: how many bytes of memory are required.
> * @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 +4957,7 @@ __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_noprof(const void *p, size_t new_size, gfp_t flags, int nid)
> {
> void *ret;
>
> @@ -4956,13 +4966,13 @@ 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, flags, nid);
> if (ret && kasan_reset_tag(p) != kasan_reset_tag(ret))
> kfree(p);
>
> return ret;
> }
> -EXPORT_SYMBOL(krealloc_noprof);
> +EXPORT_SYMBOL(krealloc_node_noprof);
>
> static gfp_t kmalloc_gfp_adjust(gfp_t flags, size_t size)
> {
> @@ -5079,10 +5089,11 @@ void kvfree_sensitive(const void *addr, size_t len)
> EXPORT_SYMBOL(kvfree_sensitive);
>
> /**
> - * kvrealloc - reallocate memory; contents remain unchanged
> + * kvrealloc_node - reallocate memory; contents remain unchanged
> * @p: object to reallocate memory for
> * @size: the size to reallocate
> * @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 +5111,17 @@ 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_noprof(const void *p, size_t size, gfp_t flags, int nid)
> {
> void *n;
>
> if (is_vmalloc_addr(p))
> - return vrealloc_noprof(p, size, flags);
> + return vrealloc_node_noprof(p, size, 1, flags, nid);
>
> - n = krealloc_noprof(p, size, kmalloc_gfp_adjust(flags, size));
> + n = krealloc_node_noprof(p, size, kmalloc_gfp_adjust(flags, size), nid);
> if (!n) {
> /* We failed to krealloc(), fall back to kvmalloc(). */
> - n = kvmalloc_noprof(size, flags);
> + n = kvmalloc_node_noprof(size, flags, nid);
> if (!n)
> return NULL;
>
> @@ -5126,7 +5137,7 @@ void *kvrealloc_noprof(const void *p, size_t size, gfp_t flags)
>
> return n;
> }
> -EXPORT_SYMBOL(kvrealloc_noprof);
> +EXPORT_SYMBOL(kvrealloc_node_noprof);
>
> struct detached_freelist {
> struct slab *slab;
> --
> 2.39.2
>
>
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