[PATCH RFC 06/35] mm/page_alloc: reject unreasonable folio/compound page sizes in alloc_contig_range_noprof()
From: David Hildenbrand <hidden>
Date: 2025-08-21 20:07:28
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, memory management - core, memory management - page allocator, the rest · Maintainers:
Andrew Morton, David Hildenbrand, Vlastimil Babka, Linus Torvalds
Let's reject them early, which in turn makes folio_alloc_gigantic() reject them properly. To avoid converting from order to nr_pages, let's just add MAX_FOLIO_ORDER and calculate MAX_FOLIO_NR_PAGES based on that. Signed-off-by: David Hildenbrand <redacted> --- include/linux/mm.h | 6 ++++-- mm/page_alloc.c | 5 ++++- 2 files changed, 8 insertions(+), 3 deletions(-)
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 00c8a54127d37..77737cbf2216a 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h@@ -2055,11 +2055,13 @@ static inline long folio_nr_pages(const struct folio *folio) /* Only hugetlbfs can allocate folios larger than MAX_ORDER */ #ifdef CONFIG_ARCH_HAS_GIGANTIC_PAGE -#define MAX_FOLIO_NR_PAGES (1UL << PUD_ORDER) +#define MAX_FOLIO_ORDER PUD_ORDER #else -#define MAX_FOLIO_NR_PAGES MAX_ORDER_NR_PAGES +#define MAX_FOLIO_ORDER MAX_PAGE_ORDER #endif +#define MAX_FOLIO_NR_PAGES (1UL << MAX_FOLIO_ORDER) + /* * compound_nr() returns the number of pages in this potentially compound * page. compound_nr() can be called on a tail page, and is defined to
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index ca9e6b9633f79..1e6ae4c395b30 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c@@ -6833,6 +6833,7 @@ static int __alloc_contig_verify_gfp_mask(gfp_t gfp_mask, gfp_t *gfp_cc_mask) int alloc_contig_range_noprof(unsigned long start, unsigned long end, acr_flags_t alloc_flags, gfp_t gfp_mask) { + const unsigned int order = ilog2(end - start); unsigned long outer_start, outer_end; int ret = 0;
@@ -6850,6 +6851,9 @@ int alloc_contig_range_noprof(unsigned long start, unsigned long end, PB_ISOLATE_MODE_CMA_ALLOC : PB_ISOLATE_MODE_OTHER; + if (WARN_ON_ONCE((gfp_mask & __GFP_COMP) && order > MAX_FOLIO_ORDER)) + return -EINVAL; + gfp_mask = current_gfp_context(gfp_mask); if (__alloc_contig_verify_gfp_mask(gfp_mask, (gfp_t *)&cc.gfp_mask)) return -EINVAL;
@@ -6947,7 +6951,6 @@ int alloc_contig_range_noprof(unsigned long start, unsigned long end, free_contig_range(end, outer_end - end); } else if (start == outer_start && end == outer_end && is_power_of_2(end - start)) { struct page *head = pfn_to_page(start); - int order = ilog2(end - start); check_new_pages(head, order); prep_new_page(head, order, gfp_mask, 0);
--
2.50.1