linux-kernel - [PATCH 3/3] mm/hugetlb: add FOLL_MIGRATION validation before waiting for a migration entry

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Message-Id: <0ec5d75781452af85e6226e1b5940ff557c6f5e7.1660902741.git.baolin.wang@linux.alibaba.com>
Date:   Fri, 19 Aug 2022 18:12:58 +0800
From:   Baolin Wang <baolin.wang@...ux.alibaba.com>
To:     akpm@...ux-foundation.org, songmuchun@...edance.com,
        mike.kravetz@...cle.com
Cc:     baolin.wang@...ux.alibaba.com, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH 3/3] mm/hugetlb: add FOLL_MIGRATION validation before waiting for a migration entry

The hugetlb should keep the same logics with normal page when waiting
for a migration pte entry, that means we should also validate if
the FOLL_MIGRATION flag is set before waiting for a migration pte entry
of a hugetlb page.

Signed-off-by: Baolin Wang <baolin.wang@...ux.alibaba.com>
---
 mm/hugetlb.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index efb53ba..fac1b33 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -7000,6 +7000,11 @@ struct page * __weak
 			goto out;
 		}
 	} else {
+		if (!(flags & FOLL_MIGRATION)) {
+			page = NULL;
+			goto out;
+		}
+
 		if (is_hugetlb_entry_migration(pte)) {
 			spin_unlock(ptl);
 			__migration_entry_wait_huge((pte_t *)pmd, ptl);
@@ -7038,6 +7043,11 @@ struct page * __weak
 			goto out;
 		}
 	} else {
+		if (!(flags & FOLL_MIGRATION)) {
+			page = NULL;
+			goto out;
+		}
+
 		if (is_hugetlb_entry_migration(pte)) {
 			spin_unlock(ptl);
 			__migration_entry_wait(mm, (pte_t *)pud, ptl);
-- 
1.8.3.1