hwpoison: fix the handling path of the victimized page frame that belong to non-LRU

hwpoison: fix the handling path of the victimized page frame that belong to non-LRU

Until now, the kernel has the same policy to handle victimized page frames
that belong to kernel-space(reserved/slab-subsystem) or non-LRU(unknown
page state).  In other word, the result of handling either of these
victimized page frames is (IGNORED | FAILED), and the return value of
memory_failure() is -EBUSY.

This patch is to avoid that memory_failure() returns very soon due to the
"true" value of (!PageLRU(p)), and it also ensures that action_result()
can report more precise information("reserved kernel", "kernel slab", and
"unknown page state") instead of "non LRU", especially for memory errors
which are detected by memory-scrubbing.

Signed-off-by: Chen Yucong <slaoub@gmail.com>
Acked-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>