mm: convert page_add_anon_rmap() to use a folio internally

The API for page_add_anon_rmap() needs to be page-based, because we can
add mappings of individual pages.  But inside the function, we want to
only call compound_head() once and then use the folio APIs instead of the
page APIs that each call compound_head().

Link: https://lkml.kernel.org/r/20230111142915.1001531-7-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/rmap.c b/mm/rmap.c
index 7762ab8..7d5e0bf 100644 (file)
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -1207,10 +1207,11 @@ static void __page_check_anon_rmap(struct page *page,
  * and to ensure that PageAnon is not being upgraded racily to PageKsm
  * (but PageKsm is never downgraded to PageAnon).
  */
-void page_add_anon_rmap(struct page *page,
-       struct vm_area_struct *vma, unsigned long address, rmap_t flags)
+void page_add_anon_rmap(struct page *page, struct vm_area_struct *vma,
+               unsigned long address, rmap_t flags)
 {
-       atomic_t *mapped;
+       struct folio *folio = page_folio(page);
+       atomic_t *mapped = &folio->_nr_pages_mapped;
        int nr = 0, nr_pmdmapped = 0;
        bool compound = flags & RMAP_COMPOUND;
        bool first = true;
@@ -1219,20 +1220,18 @@ void page_add_anon_rmap(struct page *page,
        if (likely(!compound)) {
                first = atomic_inc_and_test(&page->_mapcount);
                nr = first;
-               if (first && PageCompound(page)) {
-                       mapped = subpages_mapcount_ptr(compound_head(page));
+               if (first && folio_test_large(folio)) {
                        nr = atomic_inc_return_relaxed(mapped);
                        nr = (nr < COMPOUND_MAPPED);
                }
-       } else if (PageTransHuge(page)) {
+       } else if (folio_test_pmd_mappable(folio)) {
                /* That test is redundant: it's for safety or to optimize out */
 
-               first = atomic_inc_and_test(compound_mapcount_ptr(page));
+               first = atomic_inc_and_test(&folio->_entire_mapcount);
                if (first) {
-                       mapped = subpages_mapcount_ptr(page);
                        nr = atomic_add_return_relaxed(COMPOUND_MAPPED, mapped);
                        if (likely(nr < COMPOUND_MAPPED + COMPOUND_MAPPED)) {
-                               nr_pmdmapped = thp_nr_pages(page);
+                               nr_pmdmapped = folio_nr_pages(folio);
                                nr = nr_pmdmapped - (nr & FOLIO_PAGES_MAPPED);
                                /* Raced ahead of a remove and another add? */
                                if (unlikely(nr < 0))
@@ -1248,11 +1247,11 @@ void page_add_anon_rmap(struct page *page,
        VM_BUG_ON_PAGE(!first && PageAnonExclusive(page), page);
 
        if (nr_pmdmapped)
-               __mod_lruvec_page_state(page, NR_ANON_THPS, nr_pmdmapped);
+               __lruvec_stat_mod_folio(folio, NR_ANON_THPS, nr_pmdmapped);
        if (nr)
-               __mod_lruvec_page_state(page, NR_ANON_MAPPED, nr);
+               __lruvec_stat_mod_folio(folio, NR_ANON_MAPPED, nr);
 
-       if (likely(!PageKsm(page))) {
+       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,