Re: [RFC PATCH v2 35/51] mm: guestmem_hugetlb: Add support for splitting and merging pages

[Sean Christopherson]

On Wed, May 14, 2025, Ackerley Tng wrote:
>  const struct guestmem_allocator_operations guestmem_hugetlb_ops = {
>  	.inode_setup = guestmem_hugetlb_setup,
>  	.inode_teardown = guestmem_hugetlb_teardown,
>  	.alloc_folio = guestmem_hugetlb_alloc_folio,
> +	.split_folio = guestmem_hugetlb_split_folio,
> +	.merge_folio = guestmem_hugetlb_merge_folio,
> +	.free_folio = guestmem_hugetlb_free_folio,
>  	.nr_pages_in_folio = guestmem_hugetlb_nr_pages_in_folio,
>  };
>  EXPORT_SYMBOL_GPL(guestmem_hugetlb_ops);

Don't bury exports in an "ops" like this.  Be very explicit in what is exported.
_If_ KVM needs a layer of indirection to support multiple, custom guest_memfd
allocators, then KVM can wire up ops as above.  Indirectly exporting core mm/
functionality via an ops structure like this is unnecessarily sneaky.