Yin Fengwei <fengwei.yin@xxxxxxxxx> writes:
> page_add_file_rmap_range() allows to add specific range of
> large folio rmap.
>
> Signed-off-by: Yin Fengwei <fengwei.yin@xxxxxxxxx>
> ---
> include/linux/rmap.h | 2 ++
> mm/rmap.c | 70 ++++++++++++++++++++++++++++----------------
> 2 files changed, 46 insertions(+), 26 deletions(-)
>
> diff --git a/include/linux/rmap.h b/include/linux/rmap.h
> index a6bd1f0a183d..063e0addcbf8 100644
> --- a/include/linux/rmap.h
> +++ b/include/linux/rmap.h
> @@ -198,6 +198,8 @@ void folio_add_new_anon_rmap(struct folio *, struct vm_area_struct *,
> unsigned long address);
> void page_add_file_rmap(struct page *, struct vm_area_struct *,
> bool compound);
> +void page_add_file_rmap_range(struct folio *, struct page *, int len,
> + struct vm_area_struct *, bool compound);
> void page_remove_rmap(struct page *, struct vm_area_struct *,
> bool compound);
>
> diff --git a/mm/rmap.c b/mm/rmap.c
> index 948ca17a96ad..cc7fe3010330 100644
> --- a/mm/rmap.c
> +++ b/mm/rmap.c
> @@ -1301,40 +1301,19 @@ void folio_add_new_anon_rmap(struct folio *folio, struct vm_area_struct *vma,
> __page_set_anon_rmap(folio, &folio->page, vma, address, 1);
> }
>
> -/**
> - * page_add_file_rmap - add pte mapping to a file page
> - * @page: the page to add the mapping to
> - * @vma: the vm area in which the mapping is added
> - * @compound: charge the page as compound or small page
> - *
> - * The caller needs to hold the pte lock.
> - */
> -void page_add_file_rmap(struct page *page, struct vm_area_struct *vma,
> - bool compound)
> +void page_add_file_rmap_range(struct folio *folio, struct page *page, int len,
> + struct vm_area_struct *vma, bool compound)
> {
> - struct folio *folio = page_folio(page);
> atomic_t *mapped = &folio->_nr_pages_mapped;
> - int nr = 0, nr_pmdmapped = 0;
> + int nr = 0, nr_pmdmapped = 0, nr_pages = folio_nr_pages(folio);
> bool first;
>
> - VM_BUG_ON_PAGE(compound && !PageTransHuge(page), page);
> -
> - /* Is page being mapped by PTE? Is this its first map to be added? */
> - if (likely(!compound)) {
> - first = atomic_inc_and_test(&page->_mapcount);
> - nr = first;
> - if (first && folio_test_large(folio)) {
> - nr = atomic_inc_return_relaxed(mapped);
> - nr = (nr < COMPOUND_MAPPED);
> - }
> - } else if (folio_test_pmd_mappable(folio)) {
> - /* That test is redundant: it's for safety or to optimize out */
> -
> + if (compound) {
> first = atomic_inc_and_test(&folio->_entire_mapcount);
> if (first) {
> nr = atomic_add_return_relaxed(COMPOUND_MAPPED, mapped);
> if (likely(nr < COMPOUND_MAPPED + COMPOUND_MAPPED)) {
> - nr_pmdmapped = folio_nr_pages(folio);
> + nr_pmdmapped = nr_pages;
> nr = nr_pmdmapped - (nr & FOLIO_PAGES_MAPPED);
> /* Raced ahead of a remove and another add? */
> if (unlikely(nr < 0))
> @@ -1344,6 +1323,20 @@ void page_add_file_rmap(struct page *page, struct vm_area_struct *vma,
> nr = 0;
> }
> }
> + } else {
> + int i = 0, new_mapped = 0, count;
> +
> + count = min_t(int, len, nr_pages - folio_page_idx(folio, page));
It appears that count isn't used after assignment.
Best Regards,
Huang, Ying
> + do {
> + first = atomic_inc_and_test(&page->_mapcount);
> + new_mapped = first;
> + if (first && folio_test_large(folio)) {
> + new_mapped = atomic_inc_return_relaxed(mapped);
> + new_mapped = (new_mapped < COMPOUND_MAPPED);
> + }
> + if (new_mapped)
> + nr++;
> + } while (page++, ++i < len);
> }
>
> if (nr_pmdmapped)
> @@ -1355,6 +1348,31 @@ void page_add_file_rmap(struct page *page, struct vm_area_struct *vma,
> mlock_vma_folio(folio, vma, compound);
> }
>
> +/**
> + * page_add_file_rmap - add pte mapping to a file page
> + * @page: the page to add the mapping to
> + * @vma: the vm area in which the mapping is added
> + * @compound: charge the page as compound or small page
> + *
> + * The caller needs to hold the pte lock.
> + */
> +void page_add_file_rmap(struct page *page, struct vm_area_struct *vma,
> + bool compound)
> +{
> + struct folio *folio = page_folio(page);
> + int nr_pages;
> +
> + VM_BUG_ON_PAGE(compound && !PageTransHuge(page), page);
> +
> + if (likely(!compound))
> + nr_pages = 1;
> + else
> + nr_pages = folio_nr_pages(folio);
> +
> + page_add_file_rmap_range(folio, page, nr_pages, vma, compound);
> +}
> +
> /**
> * page_remove_rmap - take down pte mapping from a page
> * @page: page to remove mapping from
