hugetlb file truncation/hole punch code may need to back out and take
locks in order in the routine hugetlb_unmap_file_folio().  This code could
race with vma freeing as pointed out in [1] and result in accessing a
stale vma pointer.  To address this, take the vma_lock when clearing the
vma_lock->vma pointer.

[1] https://lore.kernel.org/linux-mm/01f10195-7088-4462-6def-909549c75ef4@huawei.com/

[mike.kravetz@oracle.com: address build issues]
  Link: https://lkml.kernel.org/r/Yz5L1uxQYR1VqFtJ@monkey
Link: https://lkml.kernel.org/r/20221005011707.514612-3-mike.kravetz@oracle.com
Fixes: "hugetlb: use new vma_lock for pmd sharing synchronization"
Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: James Houghton <jthoughton@google.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mina Almasry <almasrymina@google.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Naoya Horiguchi <naoya.horiguchi@linux.dev>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Prakash Sangappa <prakash.sangappa@oracle.com>
Cc: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>