mm/memory-failure.c: fix race with changing page more robustly

We're only intended to deal with the non-Compound page after we split
thp in memory_failure.  However, the page could have changed compound
pages due to race window.  If this happens, we could retry once to
hopefully handle the page next round.  Also remove unneeded orig_head.
It's always equal to the hpage.  So we can use hpage directly and remove
this redundant one.

Link: https://lkml.kernel.org/r/20220218090118.1105-5-linmiaohe@huawei.com


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>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>