Commit b14224fb authored by Matthew Wilcox (Oracle)'s avatar Matthew Wilcox (Oracle) Committed by Andrew Morton
Browse files

mm: convert total_compound_mapcount() to folio_total_mapcount() 

Instead of enforcing that the argument must be a head page by naming,
enforce it with the compiler by making it a folio.  Also rename the
counter in struct folio from _compound_mapcount to _entire_mapcount.

Link: https://lkml.kernel.org/r/20230111142915.1001531-5-willy@infradead.org


Signed-off-by: default avatarMatthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 6eee1a00

include/linux/mm.h

+3 −3
Original line number Diff line number Diff line
@@ -871,7 +871,7 @@ static inline int page_mapcount(struct page *page) 
	return head_compound_mapcount(page) + mapcount;

}



int total_compound_mapcount(struct page *head);

int folio_total_mapcount(struct folio *folio);



/**

 * folio_mapcount() - Calculate the number of mappings of this folio.
@@ -888,14 +888,14 @@ static inline int folio_mapcount(struct folio *folio) 
{

	if (likely(!folio_test_large(folio)))

		return atomic_read(&folio->_mapcount) + 1;

	return total_compound_mapcount(&folio->page);

	return folio_total_mapcount(folio);

}



static inline int total_mapcount(struct page *page)

{

	if (likely(!PageCompound(page)))

		return atomic_read(&page->_mapcount) + 1;

	return total_compound_mapcount(compound_head(page));

	return folio_total_mapcount(page_folio(page));

}



static inline bool folio_large_is_mapped(struct folio *folio)

include/linux/mm_types.h

+3 −3
Original line number Diff line number Diff line
@@ -306,7 +306,7 @@ static inline struct page *encoded_page_ptr(struct encoded_page *page) 
 * @_head_1: Points to the folio.  Do not use.

 * @_folio_dtor: Which destructor to use for this folio.

 * @_folio_order: Do not use directly, call folio_order().

 * @_compound_mapcount: Do not use directly, call folio_entire_mapcount().

 * @_entire_mapcount: Do not use directly, call folio_entire_mapcount().

 * @_nr_pages_mapped: Do not use directly, call folio_mapcount().

 * @_pincount: Do not use directly, call folio_maybe_dma_pinned().

 * @_folio_nr_pages: Do not use directly, call folio_nr_pages().
@@ -360,7 +360,7 @@ struct folio { 
			unsigned long _head_1;

			unsigned char _folio_dtor;

			unsigned char _folio_order;

			atomic_t _compound_mapcount;

			atomic_t _entire_mapcount;

			atomic_t _nr_pages_mapped;

			atomic_t _pincount;

#ifdef CONFIG_64BIT
@@ -403,7 +403,7 @@ FOLIO_MATCH(flags, _flags_1); 
FOLIO_MATCH(compound_head, _head_1);

FOLIO_MATCH(compound_dtor, _folio_dtor);

FOLIO_MATCH(compound_order, _folio_order);

FOLIO_MATCH(compound_mapcount, _compound_mapcount);

FOLIO_MATCH(compound_mapcount, _entire_mapcount);

FOLIO_MATCH(subpages_mapcount, _nr_pages_mapped);

FOLIO_MATCH(compound_pincount, _pincount);

#ifdef CONFIG_64BIT

mm/rmap.c

+10 −11
Original line number Diff line number Diff line
@@ -1078,27 +1078,26 @@ int pfn_mkclean_range(unsigned long pfn, unsigned long nr_pages, pgoff_t pgoff, 
	return page_vma_mkclean_one(&pvmw);

}



int total_compound_mapcount(struct page *head)

int folio_total_mapcount(struct folio *folio)

{

	struct folio *folio = (struct folio *)head;

	int mapcount = head_compound_mapcount(head);

	int nr_subpages;

	int mapcount = folio_entire_mapcount(folio);

	int nr_pages;

	int i;



	/* In the common case, avoid the loop when no subpages mapped by PTE */

	/* In the common case, avoid the loop when no pages mapped by PTE */

	if (folio_nr_pages_mapped(folio) == 0)

		return mapcount;

	/*

	 * Add all the PTE mappings of those subpages mapped by PTE.

	 * Limit the loop, knowing that only subpages_mapcount are mapped?

	 * Add all the PTE mappings of those pages mapped by PTE.

	 * Limit the loop to folio_nr_pages_mapped()?

	 * Perhaps: given all the raciness, that may be a good or a bad idea.

	 */

	nr_subpages = thp_nr_pages(head);

	for (i = 0; i < nr_subpages; i++)

		mapcount += atomic_read(&head[i]._mapcount);

	nr_pages = folio_nr_pages(folio);

	for (i = 0; i < nr_pages; i++)

		mapcount += atomic_read(&folio_page(folio, i)->_mapcount);



	/* But each of those _mapcounts was based on -1 */

	mapcount += nr_subpages;

	mapcount += nr_pages;

	return mapcount;

}