[PATCH RFC 6/6] mm/mm_init: initialize page->_mapcount directly in__init_single_page()

From: David Hildenbrand
Date: Wed May 22 2024 - 17:04:59 EST


Let's simply reinitialize the page->_mapcount directly. We can now
get rid of page_mapcount_reset().

Signed-off-by: David Hildenbrand <david@xxxxxxxxxx>
---
include/linux/mm.h | 5 -----
include/linux/mm_types.h | 2 +-
mm/mm_init.c | 2 +-
3 files changed, 2 insertions(+), 7 deletions(-)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 018e7c0265ca..3e1d3b0d545e 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1206,11 +1206,6 @@ static inline int folio_entire_mapcount(const struct folio *folio)
return atomic_read(&folio->_entire_mapcount) + 1;
}

-static inline void page_mapcount_reset(struct page *page)
-{
- atomic_set(&(page)->_mapcount, -1);
-}
-
/**
* page_mapcount() - Number of times this precise page is mapped.
* @page: The page.
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index 6dae8e15037b..c377c040f87d 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -169,7 +169,7 @@ struct page {
* See page-flags.h for a list of page types which are currently
* stored here.
*
- * Owners of typed folios may reuse the lower 16bit of the
+ * Owners of typed folios may reuse the lower 16 bit of the
* head page page_type field after setting the page type,
* but must reset these 16 bit to -1 before clearing the
* page type.
diff --git a/mm/mm_init.c b/mm/mm_init.c
index f72b852bd5b8..b4916751edce 100644
--- a/mm/mm_init.c
+++ b/mm/mm_init.c
@@ -568,7 +568,7 @@ void __meminit __init_single_page(struct page *page, unsigned long pfn,
mm_zero_struct_page(page);
set_page_links(page, zone, nid, pfn);
init_page_count(page);
- page_mapcount_reset(page);
+ atomic_set(&page->_mapcount, -1);
page_cpupid_reset_last(page);
page_kasan_tag_reset(page);

--
2.45.0