[PATCH v1 12/36] mm: simplify folio_page() and folio_page_idx()
From: David Hildenbrand <hidden>
Date: 2025-08-27 22:05:51
Also in:
dri-devel, intel-gfx, io-uring, kvm, linux-arm-kernel, linux-crypto, linux-ide, linux-iommu, linux-kselftest, linux-mips, linux-mm, linux-mmc, linux-riscv, linux-s390, linux-scsi, lkml, virtualization
Subsystem:
memory management - core, the rest · Maintainers:
Andrew Morton, David Hildenbrand, Linus Torvalds
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(). Reviewed-by: Zi Yan <ziy@nvidia.com> Signed-off-by: David Hildenbrand <redacted> --- 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 2dee79fa2efcf..f6880e3225c5c 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 5ee6ffbdbf831..faf17ca211b4f 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 n) +{ + return &folio->page + n; +} static __always_inline int PageTail(const struct page *page) {
--
2.50.1