From: Miaohe Lin <linmiaohe@huawei.com>
Date: Tue, 16 Aug 2022 13:05:51 +0000 (+0800)
Subject: mm: hugetlb_vmemmap: add missing smp_wmb() before set_pte_at()
X-Git-Tag: howlett/maple/20220906~107
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=04ac2d757731e6a83e3ec50a347f9a75c5a827c2;p=users%2Fjedix%2Flinux-maple.git

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.

Link: https://lkml.kernel.org/r/20220816130553.31406-5-linmiaohe@huawei.com
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

diff --git a/mm/hugetlb_vmemmap.c b/mm/hugetlb_vmemmap.c
index 20f414c0379f9..76b2d03a0d8dd 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));
 }