From: Anshuman Khandual <anshuman.khandual@xxxxxxx> [ Upstream commit 1e5823c8e86de83a43d59a522b4de29066d3b306 ] This asserts that HUGE_MAX_HSTATE is sufficient enough preventing potential hugetlb_max_hstate runtime overflow in hugetlb_add_hstate() thus triggering a BUG_ON() there after. Cc: Catalin Marinas <catalin.marinas@xxxxxxx> Cc: Will Deacon <will@xxxxxxxxxx> Cc: Ard Biesheuvel <ardb@xxxxxxxxxx> Cc: Ryan Roberts <ryan.roberts@xxxxxxx> Cc: Mark Rutland <mark.rutland@xxxxxxx> Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx Cc: linux-kernel@xxxxxxxxxxxxxxx Signed-off-by: Anshuman Khandual <anshuman.khandual@xxxxxxx> Reviewed-by: Ryan Roberts <ryan.roberts@xxxxxxx> Reviewed-by: Gavin Shan <gshan@xxxxxxxxxx> Link: https://lore.kernel.org/r/20241202064407.53807-1-anshuman.khandual@xxxxxxx Signed-off-by: Will Deacon <will@xxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- arch/arm64/mm/hugetlbpage.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/arch/arm64/mm/hugetlbpage.c b/arch/arm64/mm/hugetlbpage.c index 3215adf48a1b6..98a2a0e64e255 100644 --- a/arch/arm64/mm/hugetlbpage.c +++ b/arch/arm64/mm/hugetlbpage.c @@ -519,6 +519,18 @@ pte_t huge_ptep_clear_flush(struct vm_area_struct *vma, static int __init hugetlbpage_init(void) { + /* + * HugeTLB pages are supported on maximum four page table + * levels (PUD, CONT PMD, PMD, CONT PTE) for a given base + * page size, corresponding to hugetlb_add_hstate() calls + * here. + * + * HUGE_MAX_HSTATE should at least match maximum supported + * HugeTLB page sizes on the platform. Any new addition to + * supported HugeTLB page sizes will also require changing + * HUGE_MAX_HSTATE as well. + */ + BUILD_BUG_ON(HUGE_MAX_HSTATE < 4); if (pud_sect_supported()) hugetlb_add_hstate(PUD_SHIFT - PAGE_SHIFT); -- 2.39.5
