Re: [PATCH bpf-next] bpf: Add kernel-doc for arena page kfuncs

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Low] The kernel-doc for bpf_arena_alloc_pages() incorrectly states that it returns a "Kernel pointer", when it actually returns a user-space virtual address.
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commit 8a97e4811ec22b9983c311e1250cbacc95c0359e
Author: Dhiraj Shah <find.dhiraj@gmail.com>

bpf: Add kernel-doc for arena page kfuncs

This patch adds kernel-doc comments for the BPF arena page-management
kfuncs. It also updates the documentation to render these blocks in a new
subsection within Documentation/bpf/kfuncs.rst.

[ ... ]

> diff --git a/kernel/bpf/arena.c b/kernel/bpf/arena.c
> index 49a8f7b1beef5..b8ec2953dee68 100644
> --- a/kernel/bpf/arena.c
> +++ b/kernel/bpf/arena.c
> @@ -870,6 +870,33 @@ static void arena_free_irq(struct irq_work *iw)
>  
>  __bpf_kfunc_start_defs();
>  
> +/**
> + * bpf_arena_alloc_pages() - Allocate pages within a BPF arena.

[ ... ]

> + * The underlying allocator may sleep, so this kfunc is only callable from
> + * sleepable BPF programs.
> + *
> + * Return:
> + * * Kernel pointer to the start of the allocated region on success.

[Severity: Low]
Does this kfunc actually return a kernel pointer? 

Looking at arena_alloc_pages(), it appears to return a user-space virtual
address derived directly from the arena's user_vm_start:

kernel/bpf/arena.c:arena_alloc_pages() {
        ...
        return clear_lo32(arena->user_vm_start) + uaddr32;
}

Additionally, the kernel-doc for bpf_arena_free_pages() added in this same
patch notes that the pointer is returned "in user-space form" by
bpf_arena_alloc_pages(). Should this documentation be updated to state that
it returns a user-space pointer rather than a kernel pointer?

> + * * %NULL if @p__map is not an arena, @flags is non-zero, @page_cnt is zero
> + *   or exceeds the arena size, @addr__ign is misaligned or outside the
> + *   arena, @node_id is invalid, or the kernel is out of memory.
> + */
>  __bpf_kfunc void *bpf_arena_alloc_pages(void *p__map, void *addr__ign, u32 page_cnt,

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Sashiko AI review · https://sashiko.dev/#/patchset/20260521043553.199781-1-find.dhiraj@gmail.com?part=1