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From:   Zi Yan <zi.yan@sent.com>
To:     linux-mm@kvack.org
Cc:     David Hildenbrand <david@redhat.com>,
        Matthew Wilcox <willy@infradead.org>,
        Vlastimil Babka <vbabka@suse.cz>,
        "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>,
        Mike Kravetz <mike.kravetz@oracle.com>,
        John Hubbard <jhubbard@nvidia.com>,
        Yang Shi <shy828301@gmail.com>,
        David Rientjes <rientjes@google.com>,
        James Houghton <jthoughton@google.com>,
        Mike Rapoport <rppt@kernel.org>, linux-kernel@vger.kernel.org
Subject: [RFC PATCH v2 05/12] mm: prevent pageblock size being larger than section size.
Date:   Thu, 11 Aug 2022 19:16:36 -0400
Message-Id: <20220811231643.1012912-6-zi.yan@sent.com>
In-Reply-To: <20220811231643.1012912-1-zi.yan@sent.com>
References: <20220811231643.1012912-1-zi.yan@sent.com>
Reply-To: Zi Yan <ziy@nvidia.com>
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From: Zi Yan <ziy@nvidia.com>

Only physical pages from a section can be guaranteed to be contiguous
and so far a pageblock can only group contiguous physical pages by
design. Set pageblock_order properly to prevent pageblock going beyond
section size.

Signed-off-by: Zi Yan <ziy@nvidia.com>
Cc: Wei Yang <richard.weiyang@linux.alibaba.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Cc: linux-mm@kvack.org
Cc: linux-kernel@vger.kernel.org
---
 include/linux/pageblock-flags.h | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/include/linux/pageblock-flags.h b/include/linux/pageblock-flag=
s.h
index 358b871b07ca..2679b2b4c079 100644
--- a/include/linux/pageblock-flags.h
+++ b/include/linux/pageblock-flags.h
@@ -47,8 +47,11 @@ extern unsigned int pageblock_order;
=20
 #else /* CONFIG_HUGETLB_PAGE */
=20
-/* If huge pages are not used, group by MAX_ORDER_NR_PAGES */
-#define pageblock_order		MAX_ORDER
+/*
+ * If huge pages are not used, group by MAX_ORDER_NR_PAGES or
+ * PAGES_PER_SECTION when MAX_ORDER_NR_PAGES is larger.
+ */
+#define pageblock_order		(min(PFN_SECTION_SHIFT, MAX_ORDER))
=20
 #endif /* CONFIG_HUGETLB_PAGE */
=20
--=20
2.35.1