mm/smaps: fix race between smaps_hugetlb_range and migration

smaps_hugetlb_range() handles the pte without holdling ptl, and may be
concurrenct with migration, leaing to BUG_ON in pfn_swap_entry_to_page(). 
The race is as follows.

smaps_hugetlb_range              migrate_pages
  huge_ptep_get
                                   remove_migration_ptes
				   folio_unlock
  pfn_swap_entry_folio
    BUG_ON

To fix it, hold ptl lock in smaps_hugetlb_range().

Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Fixes: 25ee01a2fca0 ("mm: hugetlb: proc: add hugetlb-related fields to /proc/PID/smaps")
Signed-off-by: Jinjiang Tu <[email protected]>
Acked-by: David Hildenbrand <[email protected]>
Cc: Andrei Vagin <[email protected]>
Cc: Andrii Nakryiko <[email protected]>
Cc: Baolin Wang <[email protected]>
Cc: Brahmajit Das <[email protected]>
Cc: Catalin Marinas <[email protected]>
Cc: Christophe Leroy <[email protected]>
Cc: David Rientjes <[email protected]>
Cc: Dev Jain <[email protected]>
Cc: Hugh Dickins <[email protected]>
Cc: Joern Engel <[email protected]>
Cc: Kefeng Wang <[email protected]>
Cc: Lorenzo Stoakes <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Ryan Roberts <[email protected]>
Cc: Thiago Jung Bauermann <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

0 files changed, 0 insertions, 0 deletions