linux-kernel - [PATCH v2 4/6] mm: hugetlb_vmemmap: add missing smp_wmb() before set_pte

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Date:   Tue, 23 Aug 2022 11:02:07 +0800
From:   Miaohe Lin <linmiaohe@...wei.com>
To:     <akpm@...ux-foundation.org>, <mike.kravetz@...cle.com>,
        <songmuchun@...edance.com>
CC:     <lukas.bulwahn@...il.com>, <linux-mm@...ck.org>,
        <linux-kernel@...r.kernel.org>, <linmiaohe@...wei.com>
Subject: [PATCH v2 4/6] mm: hugetlb_vmemmap: add missing smp_wmb() before set_pte_at()

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@...wei.com>
Reviewed-by: Yin Fengwei <fengwei.yin@...el.com>
Reviewed-by: Muchun Song <songmuchun@...edance.com>
---
 mm/hugetlb_vmemmap.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/mm/hugetlb_vmemmap.c b/mm/hugetlb_vmemmap.c
index 196159000897..ba2a2596fb4e 100644
--- a/mm/hugetlb_vmemmap.c
+++ b/mm/hugetlb_vmemmap.c
@@ -286,6 +286,11 @@ 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