[PATCH v2 16/18] memblock: make HugeTLB bootmem allocation work with KHO

[Mike Rapoport]

On Fri, 05 Jun 2026 20:34:49 +0200, Pratyush Yadav <pratyush at kernel.org> wrote:
> Gigantic huge page allocation is somewhat broken currently when KHO is
> used.
> 
> Firstly, they break KHO scratch size accounting. RSRV_KERN is used to
> track how much memory is reserved for use by the kernel. Since
> alloc_bootmem() calls the memblock_alloc*() APIs, the hugepages

hugetlb::alloc_bootmem()

> [...]
> First, it does not use mirrored memory for hugetlb. Mirrored memory is a
> limited resource that is best saved for kernel data structures, not user
> memory.
> 
> Second, if the memory found overlaps with KHO scratch areas, it discards
> the memory and retries.

This sentence is somewhat hard to parse.

>
>
> diff --git a/mm/memblock.c b/mm/memblock.c
> index 6349c48154f4..131e54dd5d8d 100644
> --- a/mm/memblock.c
> +++ b/mm/memblock.c
> @@ -1756,6 +1761,69 @@ void * __init memblock_alloc_try_nid_raw(
> [ ... skip 51 lines ... ]
> +		if (memblock_bottom_up())
> +			start = addr + size;
> +		else
> +			start = addr - size;
> +
> +		goto retry;

Hmm, two goto retry don't seem nice :/
Although I can't see how to imporove it really.

Maybe add a helper for going the node fallback?

-- 
Sincerely yours,
Mike.