+ rmap-add-folio_add_file_rmap_range.patch added to mm-unstable branch

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The patch titled
     Subject: rmap: add folio_add_file_rmap_range()
has been added to the -mm mm-unstable branch.  Its filename is
     rmap-add-folio_add_file_rmap_range.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/rmap-add-folio_add_file_rmap_range.patch

This patch will later appear in the mm-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: Yin Fengwei <fengwei.yin@xxxxxxxxx>
Subject: rmap: add folio_add_file_rmap_range()
Date: Wed, 2 Aug 2023 16:14:03 +0100

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@xxxxxxxxxxxxx
Signed-off-by: Yin Fengwei <fengwei.yin@xxxxxxxxx>
Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---

 include/linux/rmap.h |    2 +
 mm/rmap.c            |   60 +++++++++++++++++++++++++++++++----------
 2 files changed, 48 insertions(+), 14 deletions(-)

--- a/include/linux/rmap.h~rmap-add-folio_add_file_rmap_range
+++ a/include/linux/rmap.h
@@ -198,6 +198,8 @@ void folio_add_new_anon_rmap(struct foli
 		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);
 void folio_remove_rmap_range(struct folio *folio, struct page *page,
--- a/mm/rmap.c~rmap-add-folio_add_file_rmap_range
+++ a/mm/rmap.c
@@ -1294,31 +1294,39 @@ void folio_add_new_anon_rmap(struct foli
 }
 
 /**
- * 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 */
 
@@ -1348,6 +1356,30 @@ void page_add_file_rmap(struct page *pag
 }
 
 /**
+ * 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);
+}
+
+/**
  * __remove_rmap_finish - common operations when taking down a mapping.
  * @folio:	Folio containing all pages taken down.
  * @vma:	The VM area containing the range.
_

Patches currently in -mm which might be from fengwei.yin@xxxxxxxxx are

madvise-madvise_cold_or_pageout_pte_range-dont-use-mapcount-against-large-folio-for-sharing-check.patch
madvise-madvise_free_huge_pmd-dont-use-mapcount-against-large-folio-for-sharing-check.patch
madvise-madvise_free_pte_range-dont-use-mapcount-against-large-folio-for-sharing-check.patch
filemap-add-filemap_map_folio_range.patch
rmap-add-folio_add_file_rmap_range.patch
mm-convert-do_set_pte-to-set_pte_range.patch
filemap-batch-pte-mappings.patch




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