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 <david@xxxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: linux-mm@xxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
Signed-off-by: Anshuman Khandual <anshuman.khandual@xxxxxxx>
---
Changes in V2:
- Changed WARN_ON() to BUILD_BUG_ON() per David
Changes in V1:
https://patchwork.kernel.org/project/linux-mm/patch/1617947717-2424-1-git-send-email-anshuman.khandual@xxxxxxx/
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
