linux-kernel - [PATCH v3 2/3] mm/hugetlb: Use hugetlb_pte

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Message-Id: <20221004193400.110155-3-peterx@redhat.com>
Date:   Tue,  4 Oct 2022 15:33:59 -0400
From:   Peter Xu <peterx@...hat.com>
To:     linux-mm@...ck.org, linux-kernel@...r.kernel.org
Cc:     Mike Rapoport <rppt@...ux.vnet.ibm.com>, peterx@...hat.com,
        David Hildenbrand <david@...hat.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Andrea Arcangeli <aarcange@...hat.com>,
        Nadav Amit <nadav.amit@...il.com>,
        Axel Rasmussen <axelrasmussen@...gle.com>,
        Mike Kravetz <mike.kravetz@...cle.com>
Subject: [PATCH v3 2/3] mm/hugetlb: Use hugetlb_pte_stable in migration race check

After hugetlb_pte_stable() introduced, we can also rewrite the migration
race condition against page allocation to use the new helper too.

Reviewed-by: Mike Kravetz <mike.kravetz@...cle.com>
Reviewed-by: David Hildenbrand <david@...hat.com>
Signed-off-by: Peter Xu <peterx@...hat.com>
---
 mm/hugetlb.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 1f059acc38f3..63fe47a0240a 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -5623,11 +5623,10 @@ static vm_fault_t hugetlb_no_page(struct mm_struct *mm,
 			 * here.  Before returning error, get ptl and make
 			 * sure there really is no pte entry.
 			 */
-			ptl = huge_pte_lock(h, mm, ptep);
-			ret = 0;
-			if (huge_pte_none(huge_ptep_get(ptep)))
+			if (hugetlb_pte_stable(h, mm, ptep, old_pte))
 				ret = vmf_error(PTR_ERR(page));
-			spin_unlock(ptl);
+			else
+				ret = 0;
 			goto out;
 		}
 		clear_huge_page(page, address, pages_per_huge_page(h));
-- 
2.37.3