[PATCH 11/15] mm/rmap, gup: use folio_page() for PageAnonExclusive and gup_must_unshare

[Nilay Vaish]

As part of the memdescs effort, struct folio will be allocated
separately from struct page and will no longer overlay the head page.

Replace &folio->page with folio_page(folio, 0) when checking or setting
PageAnonExclusive() in folio_add_new_anon_rmap(),
hugetlb_add_anon_rmap(), hugetlb_add_new_anon_rmap(), and
sanity_check_pinned_pages(), and when calling gup_must_unshare() in
gup_fast_pmd_leaf() and gup_fast_pud_leaf().

No functional change intended.

Assisted-by: LLM
Signed-off-by: Nilay Vaish <nilayvaish@xxxxxxxxxx>
---
 mm/gup.c  | 11 +++++++----
 mm/rmap.c | 10 +++++-----
 2 files changed, 12 insertions(+), 9 deletions(-)

diff --git a/mm/gup.c b/mm/gup.c
index 8e9ef5ee7498..1ce7ea5e7abb 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -59,10 +59,11 @@ static inline void sanity_check_pinned_pages(struct page **pages,
 		    !folio_test_anon(folio))
 			continue;
 		if (!folio_test_large(folio) || folio_test_hugetlb(folio))
-			VM_WARN_ON_ONCE_FOLIO(!PageAnonExclusive(&folio->page), folio);
+			VM_WARN_ON_ONCE_FOLIO(!PageAnonExclusive(folio_page(folio, 0)),
+					      folio);
 		else
 			/* Either a PTE-mapped or a PMD-mapped THP. */
-			VM_WARN_ON_ONCE_PAGE(!PageAnonExclusive(&folio->page) &&
+			VM_WARN_ON_ONCE_PAGE(!PageAnonExclusive(folio_page(folio, 0)) &&
 					     !PageAnonExclusive(page), page);
 	}
 }
@@ -2957,7 +2958,8 @@ static unsigned long gup_fast_pmd_leaf(pmd_t orig, pmd_t *pmdp,
 		gup_put_folio(folio, nr_pages, flags);
 		return 0;
 	}
-	if (!pmd_write(orig) && gup_must_unshare(NULL, flags, &folio->page)) {
+	if (!pmd_write(orig) &&
+	    gup_must_unshare(NULL, flags, folio_page(folio, 0))) {
 		gup_put_folio(folio, nr_pages, flags);
 		return 0;
 	}
@@ -2999,7 +3001,8 @@ static unsigned long gup_fast_pud_leaf(pud_t orig, pud_t *pudp,
 		return 0;
 	}
 
-	if (!pud_write(orig) && gup_must_unshare(NULL, flags, &folio->page)) {
+	if (!pud_write(orig) &&
+	    gup_must_unshare(NULL, flags, folio_page(folio, 0))) {
 		gup_put_folio(folio, nr_pages, flags);
 		return 0;
 	}
diff --git a/mm/rmap.c b/mm/rmap.c
index fbd66a2823b7..cd1cf570c770 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -1668,7 +1668,7 @@ void folio_add_new_anon_rmap(struct folio *folio, struct vm_area_struct *vma,
 		/* increment count (starts at -1) */
 		atomic_set(&folio->_mapcount, 0);
 		if (exclusive)
-			SetPageAnonExclusive(&folio->page);
+			SetPageAnonExclusive(folio_page(folio, 0));
 	} else if (!folio_test_pmd_mappable(folio)) {
 		int i;
 
@@ -1694,7 +1694,7 @@ void folio_add_new_anon_rmap(struct folio *folio, struct vm_area_struct *vma,
 		if (IS_ENABLED(CONFIG_PAGE_MAPCOUNT))
 			atomic_set(&folio->_nr_pages_mapped, ENTIRELY_MAPPED);
 		if (exclusive)
-			SetPageAnonExclusive(&folio->page);
+			SetPageAnonExclusive(folio_page(folio, 0));
 		nr_pmdmapped = nr;
 	}
 
@@ -3187,9 +3187,9 @@ void hugetlb_add_anon_rmap(struct folio *folio, struct vm_area_struct *vma,
 	atomic_inc(&folio->_entire_mapcount);
 	atomic_inc(&folio->_large_mapcount);
 	if (flags & RMAP_EXCLUSIVE)
-		SetPageAnonExclusive(&folio->page);
+		SetPageAnonExclusive(folio_page(folio, 0));
 	VM_WARN_ON_FOLIO(folio_entire_mapcount(folio) > 1 &&
-			 PageAnonExclusive(&folio->page), folio);
+			 PageAnonExclusive(folio_page(folio, 0)), folio);
 }
 
 void hugetlb_add_new_anon_rmap(struct folio *folio,
@@ -3203,6 +3203,6 @@ void hugetlb_add_new_anon_rmap(struct folio *folio,
 	atomic_set(&folio->_large_mapcount, 0);
 	folio_clear_hugetlb_restore_reserve(folio);
 	__folio_set_anon(folio, vma, address, true);
-	SetPageAnonExclusive(&folio->page);
+	SetPageAnonExclusive(folio_page(folio, 0));
 }
 #endif /* CONFIG_HUGETLB_PAGE */
-- 
2.56.0.rc1.315.gc6ed9934b7-goog