[RFC PATCH 17/24] mm/hugetlb: Add a BUILD_BUG_ON to check if struct page size is a power of two

[Muchun Song <songmuchun@xxxxxxxxxxxxx>]

We only can free the unused vmemmap to the buddy system when the
size of struct page is a power of two. So add a BUILD_BUG_ON to
check the illegal case.

Signed-off-by: Muchun Song <songmuchun@xxxxxxxxxxxxx>
---
 mm/hugetlb.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 7072b849af3d..34706cec21ec 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -3817,6 +3817,10 @@ static int __init hugetlb_init(void)
 {
 	int i;
 
+#ifdef CONFIG_HUGETLB_PAGE_FREE_VMEMMAP
+	BUILD_BUG_ON_NOT_POWER_OF_2(sizeof(struct page));
+#endif
+
 	if (!hugepages_supported()) {
 		if (hugetlb_max_hstate || default_hstate_max_huge_pages)
 			pr_warn("HugeTLB: huge pages not supported, ignoring associated command-line parameters\n");
-- 
2.20.1