From d79db3f39684b008bd8ff6dbf509ef27802e4ef1 Mon Sep 17 00:00:00 2001 From: "David Hildenbrand (Arm)" Date: Thu, 16 Jul 2026 16:51:01 +0200 Subject: mm: provide free_reserved_pages(), removing x86 variant Let's extend free_reserved_page() in page_alloc.c to free_reserved_pages(), dropping the custom x86 variant. The common-code variant will consume an order, so adjust the x86 callers accordingly. Make free_reserved_pages() assume that we are freeing ordinary high-order pages, just with the special "reserved" flavor. The target use case for now is freeing vmemmap PMD pages. Set the refcount directly to 0 (instead of 1) and call __free_frozen_pages(). Set the page count to 0 before clearing PG_reserved, so someone checking PG_reserved (and not finding it set) to then try grabbing a ref would not suddenly have that ref be dropped. That is arguably cleaner and safer than the old way of doing it. Add some kerneldoc. Use a single adjust_managed_page_count() call. Link: https://lore.kernel.org/20260716-bootmem_info_part2-v2-2-4afc76c73d61@kernel.org Signed-off-by: David Hildenbrand (Arm) Reviewed-by: Mike Rapoport (Microsoft) Reviewed-by: Muchun Song Reviewed-by: Zi Yan Reviewed-by: Dave Hansen Cc: Alexander Gordeev Cc: Andy Lutomirski Cc: "Borislav Petkov (AMD)" Cc: Brendan Jackman Cc: Brendan Jackman Cc: Christian Borntraeger Cc: Gerald Schaefer Cc: Heiko Carstens Cc: "H. Peter Anvin" Cc: Ingo Molnar Cc: Johannes Weiner Cc: Liam R. Howlett Cc: Lorenzo Stoakes Cc: Michal Hocko Cc: Oscar Salvador Cc: Peter Zijlstra Cc: Suren Baghdasaryan Cc: Sven Schnelle Cc: Vasily Gorbik Cc: Vlastimil Babka Signed-off-by: Andrew Morton --- include/linux/mm.h | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) (limited to 'include') diff --git a/include/linux/mm.h b/include/linux/mm.h index 25e669632d2c..e1e1154dafd7 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -3996,8 +3996,12 @@ extern unsigned long free_reserved_area(void *start, void *end, extern void adjust_managed_page_count(struct page *page, long count); -/* Free the reserved page into the buddy system, so it gets managed. */ -void free_reserved_page(struct page *page); +void free_reserved_pages(struct page *page, unsigned int order); + +static inline void free_reserved_page(struct page *page) +{ + free_reserved_pages(page, 0); +} static inline void mark_page_reserved(struct page *page) { -- cgit v1.2.3