mm/migration: fix potential pte_unmap on an not mapped pte

__migration_entry_wait and migration_entry_wait_on_locked assume pte is
always mapped from caller.  But this is not the case when it's called from
migration_entry_wait_huge and follow_huge_pmd.  Add a hugetlbfs variant
that calls hugetlb_migration_entry_wait(ptep == NULL) to fix this issue.

Link: https://lkml.kernel.org/r/[email protected]
Fixes: 30dad30922cc ("mm: migration: add migrate_entry_wait_huge()")
Signed-off-by: Miaohe Lin <[email protected]>
Suggested-by: David Hildenbrand <[email protected]>
Reviewed-by: David Hildenbrand <[email protected]>
Cc: Alistair Popple <[email protected]>
Cc: Christoph Hellwig <[email protected]>
Cc: Christoph Lameter <[email protected]>
Cc: David Howells <[email protected]>
Cc: Huang Ying <[email protected]>
Cc: kernel test robot <[email protected]>
Cc: Mike Kravetz <[email protected]>
Cc: Muchun Song <[email protected]>
Cc: Oscar Salvador <[email protected]>
Cc: Peter Xu <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

0 files changed, 0 insertions, 0 deletions