On 21.08.25 22:55, Zi Yan wrote:
On 21 Aug 2025, at 16:06, David Hildenbrand wrote:Now that a single folio/compound page can no longer span memory sections in problematic kernel configurations, we can stop using nth_page(). While at it, turn both macros into static inline functions and add kernel doc for folio_page_idx(). Signed-off-by: David Hildenbrand <da...@redhat.com> --- include/linux/mm.h | 16 ++++++++++++++-- include/linux/page-flags.h | 5 ++++- 2 files changed, 18 insertions(+), 3 deletions(-) diff --git a/include/linux/mm.h b/include/linux/mm.h index 48a985e17ef4e..ef360b72cb05c 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -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); diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h index d53a86e68c89b..080ad10c0defc 100644 --- a/include/linux/page-flags.h +++ b/include/linux/page-flags.h @@ -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 nr) +{ + return &folio->page + nr; +}Maybe s/nr/n/ or s/nr/nth/, since it returns the nth page within a folio.
Yeah, it's even called "n" in the kernel docs ...
Since you have added kernel doc for folio_page_idx(), it does not hurt to have something similar for folio_page(). :)
... which we already have! (see above the macro) :) Thanks! -- Cheers David / dhildenb
