From: Anshuman Khandual <anshuman.khandual@arm.com>
To: linux-mm@kvack.org, akpm@linux-foundation.org
Cc: Anshuman Khandual <anshuman.khandual@arm.com>,
David Hildenbrand <david@redhat.com>,
linux-kernel@vger.kernel.org
Subject: [PATCH V2] mm/page_alloc: Ensure that HUGETLB_PAGE_ORDER is less than MAX_ORDER
Date: Mon, 12 Apr 2021 09:18:22 +0530 [thread overview]
Message-ID: <1618199302-29335-1-git-send-email-anshuman.khandual@arm.com> (raw)
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@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-mm@kvack.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
---
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@arm.com/
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
next reply other threads:[~2021-04-12 3:47 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-12 3:48 Anshuman Khandual [this message]
2021-04-12 8:06 ` [PATCH V2] mm/page_alloc: Ensure that HUGETLB_PAGE_ORDER is less than MAX_ORDER Anshuman Khandual
2021-04-12 8:47 ` David Hildenbrand
2021-04-19 3:45 ` Anshuman Khandual
2021-04-19 10:48 ` Christoph Lameter
2021-04-20 9:03 ` David Hildenbrand
2021-04-12 8:10 ` kernel test robot
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