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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: David Hildenbrand <david@redhat.com>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: Wei Yang <richard.weiyang@gmail.com>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
David Hildenbrand 2025-09-01 17:03:33 +02:00 committed by Andrew Morton
parent 4751c39eee
commit 73b3294b11
2 changed files with 18 additions and 3 deletions
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16
include/linux/mm.h
View File

@ -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);

5
include/linux/page-flags.h
View File

@ -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)
{