Looks good.
Reviewed-by: William Kucharski <william.kucharski@xxxxxxxxxx>
> On Jan 16, 2023, at 12:29 PM, Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx> wrote:
>
> Avoid the compound_head() call in PageAnon() by passing in the folio that
> all callers have. Also save me from wondering whether page->mapping
> can ever be overwritten on a tail page (I don't think it can, but I'm
> not 100% sure).
>
> Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
> ---
> mm/rmap.c | 21 +++++++++++----------
> 1 file changed, 11 insertions(+), 10 deletions(-)
>
> diff --git a/mm/rmap.c b/mm/rmap.c
> index b26fbbcc9257..ab2246e6f20a 100644
> --- a/mm/rmap.c
> +++ b/mm/rmap.c
> @@ -1131,19 +1131,20 @@ void page_move_anon_rmap(struct page *page, struct vm_area_struct *vma)
>
> /**
> * __page_set_anon_rmap - set up new anonymous rmap
> - * @page: Page or Hugepage to add to rmap
> + * @folio: Folio which contains page.
> + * @page: Page to add to rmap.
> * @vma: VM area to add page to.
> * @address: User virtual address of the mapping
> * @exclusive: the page is exclusively owned by the current process
> */
> -static void __page_set_anon_rmap(struct page *page,
> +static void __page_set_anon_rmap(struct folio *folio, struct page *page,
> struct vm_area_struct *vma, unsigned long address, int exclusive)
> {
> struct anon_vma *anon_vma = vma->anon_vma;
>
> BUG_ON(!anon_vma);
>
> - if (PageAnon(page))
> + if (folio_test_anon(folio))
> goto out;
>
> /*
> @@ -1155,14 +1156,14 @@ static void __page_set_anon_rmap(struct page *page,
> anon_vma = anon_vma->root;
>
> /*
> - * page_idle does a lockless/optimistic rmap scan on page->mapping.
> + * page_idle does a lockless/optimistic rmap scan on folio->mapping.
> * Make sure the compiler doesn't split the stores of anon_vma and
> * the PAGE_MAPPING_ANON type identifier, otherwise the rmap code
> * could mistake the mapping for a struct address_space and crash.
> */
> anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON;
> - WRITE_ONCE(page->mapping, (struct address_space *) anon_vma);
> - page->index = linear_page_index(vma, address);
> + WRITE_ONCE(folio->mapping, (struct address_space *) anon_vma);
> + folio->index = linear_page_index(vma, address);
> out:
> if (exclusive)
> SetPageAnonExclusive(page);
> @@ -1254,7 +1255,7 @@ void page_add_anon_rmap(struct page *page, struct vm_area_struct *vma,
> if (likely(!folio_test_ksm(folio))) {
> /* address might be in next vma when migration races vma_adjust */
> if (first)
> - __page_set_anon_rmap(page, vma, address,
> + __page_set_anon_rmap(folio, page, vma, address,
> !!(flags & RMAP_EXCLUSIVE));
> else
> __page_check_anon_rmap(page, vma, address);
> @@ -1297,7 +1298,7 @@ void folio_add_new_anon_rmap(struct folio *folio, struct vm_area_struct *vma,
> }
>
> __lruvec_stat_mod_folio(folio, NR_ANON_MAPPED, nr);
> - __page_set_anon_rmap(&folio->page, vma, address, 1);
> + __page_set_anon_rmap(folio, &folio->page, vma, address, 1);
> }
>
> /**
> @@ -2542,7 +2543,7 @@ void hugepage_add_anon_rmap(struct page *page, struct vm_area_struct *vma,
> VM_BUG_ON_PAGE(!first && (flags & RMAP_EXCLUSIVE), page);
> VM_BUG_ON_PAGE(!first && PageAnonExclusive(page), page);
> if (first)
> - __page_set_anon_rmap(page, vma, address,
> + __page_set_anon_rmap(folio, page, vma, address,
> !!(flags & RMAP_EXCLUSIVE));
> }
>
> @@ -2555,6 +2556,6 @@ void hugepage_add_new_anon_rmap(struct page *page,
> /* increment count (starts at -1) */
> atomic_set(&folio->_entire_mapcount, 0);
> folio_clear_hugetlb_restore_reserve(folio);
> - __page_set_anon_rmap(page, vma, address, 1);
> + __page_set_anon_rmap(folio, page, vma, address, 1);
> }
> #endif /* CONFIG_HUGETLB_PAGE */
> --
> 2.35.1
>
>
