+ mm-hugetlb-use-hugetlb_pte_stable-in-migration-race-check.patch added to mm-unstable branch

[Andrew Morton <akpm@linux-foundation.org>]

The patch titled
     Subject: mm/hugetlb: use hugetlb_pte_stable in migration race check
has been added to the -mm mm-unstable branch.  Its filename is
     mm-hugetlb-use-hugetlb_pte_stable-in-migration-race-check.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-hugetlb-use-hugetlb_pte_stable-in-migration-race-check.patch

This patch will later appear in the mm-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: Peter Xu <peterx@redhat.com>
Subject: mm/hugetlb: use hugetlb_pte_stable in migration race check
Date: Tue, 4 Oct 2022 15:33:59 -0400

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

Link: https://lkml.kernel.org/r/20221004193400.110155-3-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Nadav Amit <nadav.amit@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/hugetlb.c |    7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

--- a/mm/hugetlb.c~mm-hugetlb-use-hugetlb_pte_stable-in-migration-race-check
+++ a/mm/hugetlb.c
@@ -5623,11 +5623,10 @@ static vm_fault_t hugetlb_no_page(struct
 			 * 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));
_

Patches currently in -mm which might be from peterx@redhat.com are

mm-uffd-fix-warning-without-pte_marker_uffd_wp-compiled-in.patch
mm-hugetlb-fix-race-condition-of-uffd-missing-minor-handling.patch
mm-hugetlb-use-hugetlb_pte_stable-in-migration-race-check.patch
mm-selftest-uffd-explain-the-write-missing-fault-check.patch