Commit 73b3294b authored by David Hildenbrand's avatar David Hildenbrand Committed by Andrew Morton
Browse files

mm: simplify folio_page() and folio_page_idx() 

Now that a single folio/compound page can no longer span memory sections
in problematic kernel configurations, we can stop using nth_page() in
folio_page() and folio_page_idx().

While at it, turn both macros into static inline functions and add kernel
doc for folio_page_idx().

Link: https://lkml.kernel.org/r/20250901150359.867252-13-david@redhat.com


Signed-off-by: default avatarDavid Hildenbrand <david@redhat.com>
Reviewed-by: default avatarZi Yan <ziy@nvidia.com>
Reviewed-by: default avatarWei Yang <richard.weiyang@gmail.com>
Reviewed-by: default avatarLorenzo Stoakes <lorenzo.stoakes@oracle.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 4751c39e

include/linux/mm.h

+14 −2
Original line number Diff line number Diff line
@@ -210,10 +210,8 @@ extern unsigned long sysctl_admin_reserve_kbytes; 


#if defined(CONFIG_SPARSEMEM) && !defined(CONFIG_SPARSEMEM_VMEMMAP)

#define nth_page(page,n) pfn_to_page(page_to_pfn((page)) + (n))

#define folio_page_idx(folio, p)	(page_to_pfn(p) - folio_pfn(folio))

#else

#define nth_page(page,n) ((page) + (n))

#define folio_page_idx(folio, p)	((p) - &(folio)->page)

#endif



/* to align the pointer to the (next) page boundary */
@@ -225,6 +223,20 @@ extern unsigned long sysctl_admin_reserve_kbytes; 
/* test whether an address (unsigned long or pointer) is aligned to PAGE_SIZE */

#define PAGE_ALIGNED(addr)	IS_ALIGNED((unsigned long)(addr), PAGE_SIZE)



/**

 * folio_page_idx - Return the number of a page in a folio.

 * @folio: The folio.

 * @page: The folio page.

 *

 * This function expects that the page is actually part of the folio.

 * The returned number is relative to the start of the folio.

 */

static inline unsigned long folio_page_idx(const struct folio *folio,

		const struct page *page)

{

	return page - &folio->page;

}



static inline struct folio *lru_to_folio(struct list_head *head)

{

	return list_entry((head)->prev, struct folio, lru);

include/linux/page-flags.h

+4 −1
Original line number Diff line number Diff line
@@ -316,7 +316,10 @@ static __always_inline unsigned long _compound_head(const struct page *page) 
 * check that the page number lies within @folio; the caller is presumed

 * to have a reference to the page.

 */

#define folio_page(folio, n)	nth_page(&(folio)->page, n)

static inline struct page *folio_page(struct folio *folio, unsigned long n)

{

	return &folio->page + n;

}



static __always_inline int PageTail(const struct page *page)

{