mm: memory-failure: fetch compound head after extra page refcnt is held

Page might become thp, huge page or being splited after compound head is
fetched but before page refcnt is bumped.  So hpage might be a tail page
leading to VM_BUG_ON_PAGE(PageTail(page)) in PageTransHuge().

Link: https://lkml.kernel.org/r/20230711055016.2286677-8-linmiaohe@huawei.com


Fixes: 415c64c1 ("mm/memory-failure: split thp earlier in memory error handling")
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Acked-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>