Commit 04a42e72 authored by Sidhartha Kumar's avatar Sidhartha Kumar Committed by Andrew Morton
Browse files

mm: move folio_set_compound_order() to mm/internal.h 

folio_set_compound_order() is moved to an mm-internal location so external
folio users cannot misuse this function.  Change the name of the function
to folio_set_order() and use WARN_ON_ONCE() rather than BUG_ON.  Also,
handle the case if a non-large folio is passed and add clarifying comments
to the function.

Link: https://lore.kernel.org/lkml/20221207223731.32784-1-sidhartha.kumar@oracle.com/T/
Link: https://lkml.kernel.org/r/20221215061757.223440-1-sidhartha.kumar@oracle.com


Fixes: 9fd33058 ("mm: add folio dtor and order setter functions")
Signed-off-by: default avatarSidhartha Kumar <sidhartha.kumar@oracle.com>
Suggested-by: default avatarMike Kravetz <mike.kravetz@oracle.com>
Suggested-by: default avatarMuchun Song <songmuchun@bytedance.com>
Suggested-by: default avatarMatthew Wilcox <willy@infradead.org>
Suggested-by: default avatarJohn Hubbard <jhubbard@nvidia.com>
Reviewed-by: default avatarJohn Hubbard <jhubbard@nvidia.com>
Reviewed-by: default avatarMuchun Song <songmuchun@bytedance.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 1301f931

include/linux/mm.h

+0 −16
Original line number Diff line number Diff line
@@ -1019,22 +1019,6 @@ static inline void set_compound_order(struct page *page, unsigned int order) 
#endif

}



/*

 * folio_set_compound_order is generally passed a non-zero order to

 * initialize a large folio.  However, hugetlb code abuses this by

 * passing in zero when 'dissolving' a large folio.

 */

static inline void folio_set_compound_order(struct folio *folio,

		unsigned int order)

{

	VM_BUG_ON_FOLIO(!folio_test_large(folio), folio);



	folio->_folio_order = order;

#ifdef CONFIG_64BIT

	folio->_folio_nr_pages = order ? 1U << order : 0;

#endif

}



/* Returns the number of pages in this potentially compound page. */

static inline unsigned long compound_nr(struct page *page)

{

mm/hugetlb.c

+3 −3
Original line number Diff line number Diff line
@@ -1492,7 +1492,7 @@ static void __destroy_compound_gigantic_folio(struct folio *folio, 
			set_page_refcounted(p);

	}



	folio_set_compound_order(folio, 0);

	folio_set_order(folio, 0);

	__folio_clear_head(folio);

}
@@ -1956,7 +1956,7 @@ static bool __prep_compound_gigantic_folio(struct folio *folio, 
	__folio_clear_reserved(folio);

	__folio_set_head(folio);

	/* we rely on prep_new_hugetlb_folio to set the destructor */

	folio_set_compound_order(folio, order);

	folio_set_order(folio, order);

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

		p = folio_page(folio, i);
@@ -2020,7 +2020,7 @@ static bool __prep_compound_gigantic_folio(struct folio *folio, 
		p = folio_page(folio, j);

		__ClearPageReserved(p);

	}

	folio_set_compound_order(folio, 0);

	folio_set_order(folio, 0);

	__folio_clear_head(folio);

	return false;

}

mm/internal.h

+19 −0
Original line number Diff line number Diff line
@@ -378,6 +378,25 @@ extern void *memmap_alloc(phys_addr_t size, phys_addr_t align, 
int split_free_page(struct page *free_page,

			unsigned int order, unsigned long split_pfn_offset);



/*

 * This will have no effect, other than possibly generating a warning, if the

 * caller passes in a non-large folio.

 */

static inline void folio_set_order(struct folio *folio, unsigned int order)

{

	if (WARN_ON_ONCE(!folio_test_large(folio)))

		return;



	folio->_folio_order = order;

#ifdef CONFIG_64BIT

	/*

	 * When hugetlb dissolves a folio, we need to clear the tail

	 * page, rather than setting nr_pages to 1.

	 */

	folio->_folio_nr_pages = order ? 1U << order : 0;

#endif

}



#if defined CONFIG_COMPACTION || defined CONFIG_CMA



/*