rmap: add folio_add_file_rmap_range()

folio_add_file_rmap_range() allows to add pte mapping to a specific range
of file folio.  Comparing to page_add_file_rmap(), it batched updates
__lruvec_stat for large folio.

Link: https://lkml.kernel.org/r/20230802151406.3735276-36-willy@infradead.org
Signed-off-by: Yin Fengwei <fengwei.yin@intel.com>
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/include/linux/rmap.h b/include/linux/rmap.h
index b87d0166041273d0e3dbc466b1b296f2cb49073f..a3825ce81102cfd0e2d2097d8841c1ea73011737 100644 (file)
--- 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 folio_add_file_rmap_range(struct folio *, struct page *, unsigned int nr,
+               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 51ec8aa5e61f2d8ab0b2816b8520367ce32d2833..1f04debdc87a035ed46c0020bb6ce27544e7e4f7 100644 (file)
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -1294,31 +1294,39 @@ void folio_add_new_anon_rmap(struct folio *folio, struct vm_area_struct *vma,
 }
 
 /**
- * page_add_file_rmap - add pte mapping to a file page
- * @page:      the page to add the mapping to
+ * folio_add_file_rmap_range - add pte mapping to page range of a folio
+ * @folio:     The folio to add the mapping to
+ * @page:      The first page to add
+ * @nr_pages:  The number of pages which will be mapped
  * @vma:       the vm area in which the mapping is added
  * @compound:  charge the page as compound or small page
  *
+ * The page range of folio is defined by [first_page, first_page + nr_pages)
+ *
  * The caller needs to hold the pte lock.
  */
-void page_add_file_rmap(struct page *page, struct vm_area_struct *vma,
-               bool compound)
+void folio_add_file_rmap_range(struct folio *folio, struct page *page,
+                       unsigned int nr_pages, 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;
-       bool first;
+       unsigned int nr_pmdmapped = 0, first;
+       int nr = 0;
 
-       VM_BUG_ON_PAGE(compound && !PageTransHuge(page), page);
+       VM_WARN_ON_FOLIO(compound && !folio_test_pmd_mappable(folio), folio);
 
        /* 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);
-               }
+               do {
+                       first = atomic_inc_and_test(&page->_mapcount);
+                       if (first && folio_test_large(folio)) {
+                               first = atomic_inc_return_relaxed(mapped);
+                               first = (first < COMPOUND_MAPPED);
+                       }
+
+                       if (first)
+                               nr++;
+               } while (page++, --nr_pages > 0);
        } else if (folio_test_pmd_mappable(folio)) {
                /* That test is redundant: it's for safety or to optimize out */
 
@@ -1347,6 +1355,30 @@ 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);
+       unsigned int nr_pages;
+
+       VM_WARN_ON_ONCE_PAGE(compound && !PageTransHuge(page), page);
+
+       if (likely(!compound))
+               nr_pages = 1;
+       else
+               nr_pages = folio_nr_pages(folio);
+
+       folio_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