mm/migrate: use folio_likely_mapped_shared() in add_page_for_migration()

mm/migrate: use folio_likely_mapped_shared() in add_page_for_migration()

We want to limit the use of page_mapcount() to the places where it is
absolutely necessary.  In add_page_for_migration(), we actually want to
check if the folio is mapped shared, to reject such folios.  So let's use
folio_likely_mapped_shared() instead.

For small folios, fully mapped THP, and hugetlb folios, there is no change.
For partially mapped, shared THP, we should now do a better job at
rejecting such folios.

Link: https://lkml.kernel.org/r/20240409192301.907377-12-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Cc: Chris Zankel <chris@zankel.net>
Cc: Hugh Dickins <hughd@google.com>
Cc: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Naoya Horiguchi <nao.horiguchi@gmail.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Richard Chang <richardycc@google.com>
Cc: Rich Felker <dalias@libc.org>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Yin Fengwei <fengwei.yin@intel.com>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>