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From: Muchun Song <songmuchun@bytedance.com>
To: mike.kravetz@oracle.com, muchun.song@linux.dev,
	akpm@linux-foundation.org
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
	Muchun Song <songmuchun@bytedance.com>
Subject: [PATCH] mm: hugetlb_vmemmap: use PageCompound() instead of PageReserved()
Date: Wed, 19 Jul 2023 14:31:31 +0800	[thread overview]
Message-ID: <20230719063132.37676-1-songmuchun@bytedance.com> (raw)

The ckeck of PageReserved() is easy to be broken in the future, PageCompound()
is more stable to check if the page should be split.

Signed-off-by: Muchun Song <songmuchun@bytedance.com>
---
 mm/hugetlb_vmemmap.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/mm/hugetlb_vmemmap.c b/mm/hugetlb_vmemmap.c
index 4b9734777f69..8068fe890f52 100644
--- a/mm/hugetlb_vmemmap.c
+++ b/mm/hugetlb_vmemmap.c
@@ -73,8 +73,10 @@ static int split_vmemmap_huge_pmd(pmd_t *pmd, unsigned long start)
 		 * be treated as indepdenent small pages (as they can be freed
 		 * individually).
 		 */
-		if (!PageReserved(head))
+		if (PageCompound(head)) {
+			VM_BUG_ON(compound_order(head) != get_order(PMD_SIZE));
 			split_page(head, get_order(PMD_SIZE));
+		}
 
 		/* Make pte visible before pmd. See comment in pmd_install(). */
 		smp_wmb();
-- 
2.11.0



             reply	other threads:[~2023-07-19  6:32 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-07-19  6:31 Muchun Song [this message]
2023-07-19  6:51 ` [PATCH] mm: hugetlb_vmemmap: use PageCompound() instead of PageReserved() Mika Penttilä
2023-07-19  7:00   ` Muchun Song

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