Hi, Mike,
On Fri, May 27, 2022 at 03:58:47PM -0700, Mike Kravetz wrote:
> +unsigned long hugetlb_mask_last_hp(struct hstate *h)
> +{
> + unsigned long hp_size = huge_page_size(h);
> +
> + if (hp_size == P4D_SIZE)
> + return PGDIR_SIZE - P4D_SIZE;
> + else if (hp_size == PUD_SIZE)
> + return P4D_SIZE - PUD_SIZE;
> + else if (hp_size == PMD_SIZE)
> + return PUD_SIZE - PMD_SIZE;
> +
> + return ~(0);
> +}
How about:
unsigned long hugetlb_mask_last_hp(struct hstate *h)
{
unsigned long hp_size = huge_page_size(h);
return hp_size * (PTRS_PER_PTE - 1);
}
?
This is definitely a good idea, though I'm wondering the possibility to go
one step further to make hugetlb pgtable walk just like the normal pages.
Say, would it be non-trivial to bring some of huge_pte_offset() into the
walker functions, so that we can jump over even larger than PTRS_PER_PTE
entries (e.g. when p4d==NULL for 2m huge pages)? It's very possible I
overlooked something, though.
Thanks,
--
Peter Xu
