The patch titled
Subject: mm: convert page_mapcount() to use folio_entire_mapcount()
has been added to the -mm mm-unstable branch. Its filename is
mm-convert-page_mapcount-to-use-folio_entire_mapcount.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-convert-page_mapcount-to-use-folio_entire_mapcount.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: "Matthew Wilcox (Oracle)" <willy@xxxxxxxxxxxxx>
Subject: mm: convert page_mapcount() to use folio_entire_mapcount()
Date: Wed, 11 Jan 2023 14:29:00 +0000
Remove a use of head_compound_mapcount().
Link: https://lkml.kernel.org/r/20230111142915.1001531-15-willy@xxxxxxxxxxxxx
Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/mm.h | 22 +++++++++++++---------
1 file changed, 13 insertions(+), 9 deletions(-)
--- a/include/linux/mm.h~mm-convert-page_mapcount-to-use-folio_entire_mapcount
+++ a/include/linux/mm.h
@@ -853,22 +853,26 @@ static inline void page_mapcount_reset(s
atomic_set(&(page)->_mapcount, -1);
}
-/*
- * Mapcount of 0-order page; when compound sub-page, includes
- * compound_mapcount of compound_head of page.
+/**
+ * page_mapcount() - Number of times this precise page is mapped.
+ * @page: The page.
*
- * Result is undefined for pages which cannot be mapped into userspace.
+ * The number of times this page is mapped. If this page is part of
+ * a large folio, it includes the number of times this page is mapped
+ * as part of that folio.
+ *
+ * The result is undefined for pages which cannot be mapped into userspace.
* For example SLAB or special types of pages. See function page_has_type().
- * They use this place in struct page differently.
+ * They use this field in struct page differently.
*/
static inline int page_mapcount(struct page *page)
{
int mapcount = atomic_read(&page->_mapcount) + 1;
- if (likely(!PageCompound(page)))
- return mapcount;
- page = compound_head(page);
- return head_compound_mapcount(page) + mapcount;
+ if (unlikely(PageCompound(page)))
+ mapcount += folio_entire_mapcount(page_folio(page));
+
+ return mapcount;
}
int folio_total_mapcount(struct folio *folio);
_
Patches currently in -mm which might be from willy@xxxxxxxxxxxxx are
buffer-add-b_folio-as-an-alias-of-b_page.patch
buffer-replace-obvious-uses-of-b_page-with-b_folio.patch
buffer-use-b_folio-in-touch_buffer.patch
buffer-use-b_folio-in-end_buffer_async_read.patch
buffer-use-b_folio-in-end_buffer_async_write.patch
page_io-remove-buffer_head-include.patch
buffer-use-b_folio-in-mark_buffer_dirty.patch
gfs2-replace-obvious-uses-of-b_page-with-b_folio.patch
jbd2-replace-obvious-uses-of-b_page-with-b_folio.patch
nilfs2-replace-obvious-uses-of-b_page-with-b_folio.patch
reiserfs-replace-obvious-uses-of-b_page-with-b_folio.patch
mpage-use-b_folio-in-do_mpage_readpage.patch
mm-memcg-add-folio_memcg_check.patch
mm-remove-folio_pincount_ptr-and-head_compound_pincount.patch
mm-convert-head_subpages_mapcount-into-folio_nr_pages_mapped.patch
doc-clarify-refcount-section-by-referring-to-folios-pages.patch
mm-convert-total_compound_mapcount-to-folio_total_mapcount.patch
mm-convert-page_remove_rmap-to-use-a-folio-internally.patch
mm-convert-page_add_anon_rmap-to-use-a-folio-internally.patch
mm-convert-page_add_file_rmap-to-use-a-folio-internally.patch
mm-add-folio_add_new_anon_rmap.patch
page_alloc-use-folio-fields-directly.patch
mm-use-a-folio-in-hugepage_add_anon_rmap-and-hugepage_add_new_anon_rmap.patch
mm-use-entire_mapcount-in-__page_dup_rmap.patch
mm-debug-remove-call-to-head_compound_mapcount.patch
hugetlb-remove-uses-of-folio_mapcount_ptr.patch
mm-convert-page_mapcount-to-use-folio_entire_mapcount.patch
mm-remove-head_compound_mapcount-and-_ptr-functions.patch
mm-reimplement-compound_order.patch
mm-reimplement-compound_nr.patch
mm-convert-set_compound_page_dtor-and-set_compound_order-to-folios.patch
mm-convert-is_transparent_hugepage-to-use-a-folio.patch
mm-convert-destroy_large_folio-to-use-folio_dtor.patch
hugetlb-remove-uses-of-compound_dtor-and-compound_nr.patch
mm-remove-first-tail-page-members-from-struct-page.patch
doc-correct-struct-folio-kernel-doc.patch
mm-move-page-deferred_list-to-folio-_deferred_list.patch
mm-huge_memory-remove-page_deferred_list.patch
mm-huge_memory-convert-get_deferred_split_queue-to-take-a-folio.patch
mm-convert-deferred_split_huge_page-to-deferred_split_folio.patch
