mm/huge_memory: fix zapping migration entries for device-private THPs

A PMD migration entry can refer to a device-private folio.
zap_huge_pmd_folio() checks the folio type instead of the entry type,
so it treats such a migration entry as a device-private entry.

Installing the migration entry already removed the reverse mapping and
dropped the mapping reference. Zapping it must not repeat those
operations. Concurrent MADV_DONTNEED during migration back to system
memory can trigger this.

Check the PMD entry type using pmd_is_device_private_entry().

Fix generated by an LLM and sent by Chris Mason in private.

Fixes: 368076f52ebe ("mm/huge_memory: add device-private THP support to PMD operations")
Cc: stable@vger.kernel.org
Signed-off-by: Chris Mason <mason@kernel.org>
[ david: simplify description ]
Reviewed-by: Gregory Price (Meta) <gourry@gourry.net>
Link: https://patch.msgid.link/20261031-fixes_core-v3-14-d6437171ecc3@kernel.org
Reviewed-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: Lance Yang <lance.yang@linux.dev>
Signed-off-by: David Hildenbrand (Arm) <david@kernel.org>

0 files changed, 0 insertions, 0 deletions