linux-kernel - [PATCH v3 2/5] mm/hugetlb: use nth_page() in place of direct struct page manipulation.

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Message-Id: <20230913201248.452081-3-zi.yan@sent.com>
Date:   Wed, 13 Sep 2023 16:12:45 -0400
From:   Zi Yan <zi.yan@...t.com>
To:     linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        linux-mips@...r.kernel.org
Cc:     Zi Yan <ziy@...dia.com>, Andrew Morton <akpm@...ux-foundation.org>,
        Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
        "Matthew Wilcox (Oracle)" <willy@...radead.org>,
        David Hildenbrand <david@...hat.com>,
        Mike Kravetz <mike.kravetz@...cle.com>,
        Muchun Song <muchun.song@...ux.dev>,
        "Mike Rapoport (IBM)" <rppt@...nel.org>, stable@...r.kernel.org,
        Muchun Song <songmuchun@...edance.com>
Subject: [PATCH v3 2/5] mm/hugetlb: use nth_page() in place of direct struct page manipulation.

From: Zi Yan <ziy@...dia.com>

When dealing with hugetlb pages, manipulating struct page pointers
directly can get to wrong struct page, since struct page is not guaranteed
to be contiguous on SPARSEMEM without VMEMMAP. Use nth_page() to handle
it properly.

Fixes: 57a196a58421 ("hugetlb: simplify hugetlb handling in follow_page_mask")
Cc: <stable@...r.kernel.org>
Signed-off-by: Zi Yan <ziy@...dia.com>
Reviewed-by: Muchun Song <songmuchun@...edance.com>
---
 mm/hugetlb.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index af74e83d92aa..8e68e6c53e66 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -6469,7 +6469,7 @@ struct page *hugetlb_follow_page_mask(struct vm_area_struct *vma,
 			}
 		}
 
-		page += ((address & ~huge_page_mask(h)) >> PAGE_SHIFT);
+		page = nth_page(page, ((address & ~huge_page_mask(h)) >> PAGE_SHIFT));
 
 		/*
 		 * Note that page may be a sub-page, and with vmemmap
-- 
2.40.1