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Message-ID: <2c2f397b-e829-48f6-a8b8-29619439fef8@lucifer.local>
Date: Thu, 31 Jul 2025 13:07:21 +0100
From: Lorenzo Stoakes <lorenzo.stoakes@...cle.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>,
Vlastimil Babka <vbabka@...e.cz>, rust-for-linux@...r.kernel.org,
"Liam R . Howlett" <Liam.Howlett@...cle.com>,
Kent Overstreet <kent.overstreet@...ux.dev>,
linux-bcachefs@...r.kernel.org, bpf@...r.kernel.org,
Herbert Xu <herbert@...dor.apana.org.au>, Jann Horn <jannh@...gle.com>,
Pedro Falcato <pfalcato@...e.de>
Subject: Re: [PATCH v14 1/4] :mm/vmalloc: allow to set node and align in
vrealloc
NIT: Subject line here is typo'd, you prefixed a : by mistake. I'm sure
Andrew can yank this out though.
On Wed, Jul 30, 2025 at 09:20:02PM +0200, Vitaly Wool wrote:
> 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 alignment in its allocations.
>
> Signed-off-by: Vitaly Wool <vitaly.wool@...sulko.se>
> Reviewed-by: Uladzislau Rezki (Sony) <urezki@...il.com>
> Reviewed-by: Vlastimil Babka <vbabka@...e.cz>
Thanks for improving the comment, so:
Acked-by: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
> ---
> include/linux/vmalloc.h | 12 +++++++++---
> mm/nommu.c | 3 ++-
> mm/vmalloc.c | 29 ++++++++++++++++++++++++-----
> 3 files changed, 35 insertions(+), 9 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/nommu.c b/mm/nommu.c
> index 07504d666d6a..3bb62b779ef4 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/vmalloc.c b/mm/vmalloc.c
> index 6dbcdceecae1..e299b51bd922 100644
> --- a/mm/vmalloc.c
> +++ b/mm/vmalloc.c
> @@ -4089,19 +4089,29 @@ 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 number of the target node
> + *
> + * If @p is %NULL, vrealloc_XXX() behaves exactly like vmalloc_XXX(). If @size
> + * is 0 and @p is not a %NULL pointer, the object pointed to is freed.
> *
> - * If @p is %NULL, vrealloc() behaves exactly like vmalloc(). If @size is 0 and
> - * @p is not a %NULL pointer, the object pointed to is freed.
> + * If the caller wants the new memory to be on specific node *only*,
> + * __GFP_THISNODE flag should be set, otherwise the function will try to avoid
> + * reallocation and possibly disregard the specified @nid.
> *
> * If __GFP_ZERO logic is requested, callers must ensure that, starting with the
> * initial memory allocation, every subsequent call to this API for the same
> * memory allocation is flagged with __GFP_ZERO. Otherwise, it is possible that
> * __GFP_ZERO is not fully honored by this API.
> *
> + * Requesting an alignment that is bigger than the alignment of the existing
> + * allocation will fail.
> + *
> * In any case, the contents of the object pointed to are preserved up to the
> * lesser of the new and old sizes.
> *
> @@ -4111,7 +4121,8 @@ EXPORT_SYMBOL(vzalloc_node_noprof);
> * Return: pointer to the allocated memory; %NULL if @size is zero or in case of
> * failure
> */
Much better thanks!
> -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 +4146,12 @@ 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(!IS_ALIGNED((unsigned long)p, align),
> + "will not reallocate with a bigger alignment (0x%lx)\n", align))
> + return NULL;
> + if (unlikely(flags & __GFP_THISNODE) && nid != NUMA_NO_NODE &&
> + nid != page_to_nid(vmalloc_to_page(p)))
> + goto need_realloc;
> }
>
> /*
> @@ -4165,8 +4182,10 @@ void *vrealloc_noprof(const void *p, size_t size, gfp_t flags)
> return (void *)p;
> }
>
> +need_realloc:
> /* 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
>
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