[PATCH 4/6] mm: hugetlb_vmemmap: add missing smp_wmb() before set_pte_at()

From: Miaohe Lin <linmiaohe@huawei.com>
To: <akpm@linux-foundation.org>, <mike.kravetz@oracle.com>,
	<songmuchun@bytedance.com>
Cc: <linux-mm@kvack.org>, <linux-kernel@vger.kernel.org>,
	<linmiaohe@huawei.com>
Subject: [PATCH 4/6] mm: hugetlb_vmemmap: add missing smp_wmb() before set_pte_at()
Date: Tue, 16 Aug 2022 21:05:51 +0800	[thread overview]
Message-ID: <20220816130553.31406-5-linmiaohe@huawei.com> (raw)
In-Reply-To: <20220816130553.31406-1-linmiaohe@huawei.com>

The memory barrier smp_wmb() is needed to make sure that preceding stores
to the page contents become visible before the below set_pte_at() write.

Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
---
 mm/hugetlb_vmemmap.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/mm/hugetlb_vmemmap.c b/mm/hugetlb_vmemmap.c
index 20f414c0379f..76b2d03a0d8d 100644
--- a/mm/hugetlb_vmemmap.c
+++ b/mm/hugetlb_vmemmap.c
@@ -287,6 +287,11 @@ static void vmemmap_restore_pte(pte_t *pte, unsigned long addr,
 	copy_page(to, (void *)walk->reuse_addr);
 	reset_struct_pages(to);
 
+	/*
+	 * Makes sure that preceding stores to the page contents become visible
+	 * before the set_pte_at() write.
+	 */
+	smp_wmb();
 	set_pte_at(&init_mm, addr, pte, mk_pte(page, pgprot));
 }
 
-- 
2.23.0

