From c97eeb8f260dba098ba775e37d216f81f28559a9 Mon Sep 17 00:00:00 2001
From: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Date: Wed, 11 Jan 2023 14:29:00 +0000
Subject: [PATCH] mm: convert page_mapcount() to use folio_entire_mapcount()
Remove a use of head_compound_mapcount().
Link: https://lkml.kernel.org/r/20230111142915.1001531-15-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
include/linux/mm.h | 22 +++++++++++++---------
1 file changed, 13 insertions(+), 9 deletions(-)
diff --git a/include/linux/mm.h b/include/linux/mm.h
index bdf83e75bcd6..a6afa6c51a4d 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -853,22 +853,26 @@ static inline void page_mapcount_reset(struct page *page)
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.
+ *
+ * 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.
*
- * Result is undefined for pages which cannot be mapped into userspace.
+ * 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);
--
2.49.0