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Howlett" , Andrew Morton , Sasha Levin Subject: [PATCH 6.12 435/670] mm/page_alloc: reject unreasonable folio/compound page sizes in alloc_contig_range_noprof() Date: Fri, 13 Nov 2026 10:49:59 -0500 Message-ID: <20261113153826.557469438@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261113153811.177190860@linuxfoundation.org> References: <20261113153811.177190860@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore X-Mailing-List: patches@lists.linux.dev List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: David Hildenbrand [ Upstream commit 0bf2edf041dcb0b304a8dbda8c699771d5a245d2 ] 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. While at it, let's just make the order a "const unsigned order". Link: https://lkml.kernel.org/r/20250901150359.867252-7-david@redhat.com Signed-off-by: David Hildenbrand Reviewed-by: Zi Yan Acked-by: SeongJae Park Reviewed-by: Wei Yang Reviewed-by: Lorenzo Stoakes Reviewed-by: Liam R. Howlett Signed-off-by: Andrew Morton Stable-dep-of: 4c767c5dd9bc ("mm/page_isolation: guard compound_order() against racing") Signed-off-by: Sasha Levin --- include/linux/mm.h | 6 ++++-- mm/page_alloc.c | 10 +++++++++- 2 files changed, 13 insertions(+), 3 deletions(-) diff --git a/include/linux/mm.h b/include/linux/mm.h index 1728dc3356089..f05962963e28d 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -2058,11 +2058,13 @@ 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 063c2a359a1e1..869296e43349e 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -6685,6 +6685,7 @@ 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, unsigned migratetype, gfp_t gfp_mask) { + const unsigned int order = ilog2(end - start); unsigned long outer_start, outer_end; int ret = 0; @@ -6699,6 +6700,14 @@ int alloc_contig_range_noprof(unsigned long start, unsigned long end, }; INIT_LIST_HEAD(&cc.migratepages); + /* + * In contrast to the buddy, we allow for orders here that exceed + * MAX_PAGE_ORDER, so we must manually make sure that we are not + * exceeding the maximum folio order. + */ + 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; @@ -6796,7 +6805,6 @@ 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); -- 2.53.0