On 02/18/23 00:27, James Houghton wrote:
> hugetlb_hgm_eligible indicates that a VMA is eligible to have HGM
> explicitly enabled via MADV_SPLIT, and hugetlb_hgm_enabled indicates
> that HGM has been enabled.
>
> Signed-off-by: James Houghton <jthoughton@xxxxxxxxxx>
>
> diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
> index 7c977d234aba..efd2635a87f5 100644
> --- a/include/linux/hugetlb.h
> +++ b/include/linux/hugetlb.h
> @@ -1211,6 +1211,20 @@ static inline void hugetlb_unregister_node(struct node *node)
> }
> #endif /* CONFIG_HUGETLB_PAGE */
>
> +#ifdef CONFIG_HUGETLB_HIGH_GRANULARITY_MAPPING
> +bool hugetlb_hgm_enabled(struct vm_area_struct *vma);
> +bool hugetlb_hgm_eligible(struct vm_area_struct *vma);
> +#else
> +static inline bool hugetlb_hgm_enabled(struct vm_area_struct *vma)
> +{
> + return false;
> +}
> +static inline bool hugetlb_hgm_eligible(struct vm_area_struct *vma)
> +{
> + return false;
> +}
> +#endif
> +
> static inline spinlock_t *huge_pte_lock(struct hstate *h,
> struct mm_struct *mm, pte_t *pte)
> {
> diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> index 6c008c9de80e..0576dcc98044 100644
> --- a/mm/hugetlb.c
> +++ b/mm/hugetlb.c
> @@ -7004,6 +7004,10 @@ static bool pmd_sharing_possible(struct vm_area_struct *vma)
> #ifdef CONFIG_USERFAULTFD
> if (uffd_disable_huge_pmd_share(vma))
> return false;
> +#endif
> +#ifdef CONFIG_HUGETLB_HIGH_GRANULARITY_MAPPING
> + if (hugetlb_hgm_enabled(vma))
> + return false;
> #endif
> /*
> * Only shared VMAs can share PMDs.
> @@ -7267,6 +7271,18 @@ __weak unsigned long hugetlb_mask_last_page(struct hstate *h)
>
> #endif /* CONFIG_ARCH_WANT_GENERAL_HUGETLB */
>
> +#ifdef CONFIG_HUGETLB_HIGH_GRANULARITY_MAPPING
> +bool hugetlb_hgm_eligible(struct vm_area_struct *vma)
> +{
> + /* All shared VMAs may have HGM. */
> + return vma && (vma->vm_flags & VM_MAYSHARE);
I think the only user is madvise_split(). We should probably check here
or more likely at the beginning of madvise_split for VM_HUGETLB_HGM already
set. No sense in invoking the overhead of hugetlb_unshare_all_pmds if
not needed.
--
Mike Kravetz
> +}
> +bool hugetlb_hgm_enabled(struct vm_area_struct *vma)
> +{
> + return vma && (vma->vm_flags & VM_HUGETLB_HGM);
> +}
> +#endif /* CONFIG_HUGETLB_HIGH_GRANULARITY_MAPPING */
> +
> /*
> * These functions are overwritable if your architecture needs its own
> * behavior.
> --
> 2.39.2.637.g21b0678d19-goog
>
