mm: memory-hotplug: check folio ref count first in do_migrate_range

If a folio has an increased reference count, folio_try_get() will acquire
it, perform necessary operations, and then release it.  In the case of a
poisoned folio without an elevated reference count (which is unlikely for
memory-failure), folio_try_get() will simply bypass it.

Therefore, relocate the folio_try_get() function, responsible for checking
and acquiring this reference count at first.

Link: https://lkml.kernel.org/r/20250217014329.3610326-3-mawupeng1@huawei.com


Signed-off-by: Ma Wupeng <mawupeng1@huawei.com>
Acked-by: David Hildenbrand <david@redhat.com>
Acked-by: Miaohe Lin <linmiaohe@huawei.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Naoya Horiguchi <nao.horiguchi@gmail.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>