pageblock_order must always be less than MAX_ORDER, otherwise it might lead
to an warning during boot. A similar problem got fixed on arm64 platform
with the commit 79cc2ed5a716 ("arm64/mm: Drop THP conditionality from
FORCE_MAX_ZONEORDER"). Assert the above condition before HUGETLB_PAGE_ORDER
gets assigned as pageblock_order. This will help detect the problem earlier
on platforms where HUGETLB_PAGE_SIZE_VARIABLE is enabled.Cc: David Hildenbrand <[email protected]> Cc: Andrew Morton <[email protected]> Cc: [email protected] Cc: [email protected] Signed-off-by: Anshuman Khandual <[email protected]> --- Changes in V2: - Changed WARN_ON() to BUILD_BUG_ON() per David Changes in V1: https://patchwork.kernel.org/project/linux-mm/patch/[email protected]/ mm/page_alloc.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff --git a/mm/page_alloc.c b/mm/page_alloc.c index cfc72873961d..19283bff4bec 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -6875,10 +6875,17 @@ void __init set_pageblock_order(void) if (pageblock_order) return; - if (HPAGE_SHIFT > PAGE_SHIFT) + if (HPAGE_SHIFT > PAGE_SHIFT) { + /* + * pageblock_order must always be less than + * MAX_ORDER. So does HUGETLB_PAGE_ORDER if + * that is being assigned here. + */ + BUILD_BUG_ON(HUGETLB_PAGE_ORDER >= MAX_ORDER); order = HUGETLB_PAGE_ORDER; - else + } else { order = MAX_ORDER - 1; + } /* * Assume the largest contiguous order of interest is a huge page. -- 2.20.1
