[PATCHv7 08/18] mm/sparse: Check memmap alignment for compound_info_has_mask()
From: "Kiryl Shutsemau (Meta)" <kas@kernel.org>
Date: 2026-02-27 19:30:46
Also in:
linux-mm, linux-riscv, lkml, loongarch
Subsystem:
memory management, memory management - core, the rest · Maintainers:
Andrew Morton, David Hildenbrand, Linus Torvalds
From: Kiryl Shutsemau <kas@kernel.org> If page->compound_info encodes a mask, it is expected that vmemmap to be naturally aligned to the maximum folio size. Add a VM_WARN_ON_ONCE() to check the alignment. Signed-off-by: Kiryl Shutsemau <kas@kernel.org> Acked-by: Zi Yan <ziy@nvidia.com> --- mm/sparse.c | 5 +++++ 1 file changed, 5 insertions(+)
diff --git a/mm/sparse.c b/mm/sparse.c
index b5b2b6f7041b..dfabe554adf8 100644
--- a/mm/sparse.c
+++ b/mm/sparse.c@@ -600,6 +600,11 @@ void __init sparse_init(void) BUILD_BUG_ON(!is_power_of_2(sizeof(struct mem_section))); memblocks_present(); + if (compound_info_has_mask()) { + VM_WARN_ON_ONCE(!IS_ALIGNED((unsigned long) pfn_to_page(0), + MAX_FOLIO_VMEMMAP_ALIGN)); + } + pnum_begin = first_present_section_nr(); nid_begin = sparse_early_nid(__nr_to_section(pnum_begin));
--
2.51.2