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Date:   Mon, 3 Oct 2022 20:28:03 -0400
From:   Peter Xu <peterx@redhat.com>
To:     Mike Kravetz <mike.kravetz@oracle.com>
Cc:     linux-kernel@vger.kernel.org, linux-mm@kvack.org,
        Andrea Arcangeli <aarcange@redhat.com>,
        Mike Rapoport <rppt@linux.vnet.ibm.com>,
        David Hildenbrand <david@redhat.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Axel Rasmussen <axelrasmussen@google.com>,
        Nadav Amit <nadav.amit@gmail.com>
Subject: Re: [PATCH 1/3] mm/hugetlb: Fix race condition of uffd missing/minor
 handling
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On Mon, Oct 03, 2022 at 02:45:47PM -0700, Mike Kravetz wrote:
> This also explains why the new locking exposes the race.
> hugetlb_change_protection needs to take the i_mmap_sema in write mode because
> it could unshare pmds.  Previously, hugetlb page faults took i_mmap_sema in
> read mode so this race could not happen.

Makes sense, thanks for explaining.

-- 
Peter Xu