On 05/30/22 18:10, Baolin Wang wrote:
>
>
> On 5/28/2022 6:58 AM, Mike Kravetz wrote:
> > HugeTLB address ranges are linearly scanned during fork, unmap and
> > remap operations. If a non-present entry is encountered, the code
> > currently continues to the next huge page aligned address. However,
> > a non-present entry implies that the page table page for that entry
> > is not present. Therefore, the linear scan can skip to the end of
> > range mapped by the page table page. This can speed operations on
> > large sparsely populated hugetlb mappings.
> >
> > Create a new routine hugetlb_mask_last_hp() that will return an
> > address mask. When the mask is ORed with an address, the result
> > will be the address of the last huge page mapped by the associated
> > page table page. Use this mask to update addresses in routines which
> > linearly scan hugetlb address ranges when a non-present pte is
> > encountered.
> >
> > hugetlb_mask_last_hp is related to the implementation of huge_pte_offset
> > as hugetlb_mask_last_hp is called when huge_pte_offset returns NULL.
> > This patch only provides a complete hugetlb_mask_last_hp implementation
> > when CONFIG_ARCH_WANT_GENERAL_HUGETLB is defined. Architectures which
> > provide their own versions of huge_pte_offset can also provide their own
> > version of hugetlb_mask_last_hp.
>
> I tested on my ARM64 machine with implementing arm64 specific
> hugetlb_mask_last_hp() as below, and it works well.
>
> Just a few nits inline, otherwise looks good to me.
> Tested-by: Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx>
> Reviewed-by: Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx>
>
> diff --git a/arch/arm64/mm/hugetlbpage.c b/arch/arm64/mm/hugetlbpage.c
> index d93ba128a2b0..e04a097ffcc4 100644
> --- a/arch/arm64/mm/hugetlbpage.c
> +++ b/arch/arm64/mm/hugetlbpage.c
> @@ -376,6 +376,28 @@ pte_t *huge_pte_offset(struct mm_struct *mm,
> return NULL;
> }
>
> +unsigned long hugetlb_mask_last_hp(struct hstate *h)
> +{
> + unsigned long hp_size = huge_page_size(h);
> +
> + switch (hp_size) {
> + case P4D_SIZE:
> + return PGDIR_SIZE - P4D_SIZE;
> + case PUD_SIZE:
> + return P4D_SIZE - PUD_SIZE;
> + case CONT_PMD_SIZE:
> + return PUD_SIZE - CONT_PMD_SIZE;
> + case PMD_SIZE:
> + return PUD_SIZE - PMD_SIZE;
> + case CONT_PTE_SIZE:
> + return PMD_SIZE - CONT_PTE_SIZE;
> + default:
> + break;
> + }
> +
> + return ~(0UL);
> +}
Hello Baolin,
Would you mind sending this as a proper patch with commit message and
'Signed-off-by:'? I would like to include it in the upcoming patch series.
--
Mike Kravetz
