Let's check that no hstate that corresponds to an unreasonable folio size is registered by an architecture. If we were to succeed registering, we could later try allocating an unsupported gigantic folio size.
Further, let's add a BUILD_BUG_ON() for checking that HUGETLB_PAGE_ORDER is sane at build time. As HUGETLB_PAGE_ORDER is dynamic on powerpc, we have to use a BUILD_BUG_ON_INVALID() to make it compile.
No existing kernel configuration should be able to trigger this check: either SPARSEMEM without SPARSEMEM_VMEMMAP cannot be configured or gigantic folios will not exceed a memory section (the case on sparse).
Reviewed-by: Zi Yan ziy@nvidia.com Reviewed-by: Lorenzo Stoakes lorenzo.stoakes@oracle.com Reviewed-by: Liam R. Howlett Liam.Howlett@oracle.com Signed-off-by: David Hildenbrand david@redhat.com --- mm/hugetlb.c | 2 ++ 1 file changed, 2 insertions(+)
diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 1e777cc51ad04..d3542e92a712e 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -4657,6 +4657,7 @@ static int __init hugetlb_init(void)
BUILD_BUG_ON(sizeof_field(struct page, private) * BITS_PER_BYTE < __NR_HPAGEFLAGS); + BUILD_BUG_ON_INVALID(HUGETLB_PAGE_ORDER > MAX_FOLIO_ORDER);
if (!hugepages_supported()) { if (hugetlb_max_hstate || default_hstate_max_huge_pages) @@ -4740,6 +4741,7 @@ void __init hugetlb_add_hstate(unsigned int order) } BUG_ON(hugetlb_max_hstate >= HUGE_MAX_HSTATE); BUG_ON(order < order_base_2(__NR_USED_SUBPAGE)); + WARN_ON(order > MAX_FOLIO_ORDER); h = &hstates[hugetlb_max_hstate++]; __mutex_init(&h->resize_lock, "resize mutex", &h->resize_key); h->order = order;