mm, thp: do not queue fully unmapped pages for deferred split

mainline inclusion
from mainline-v5.5-rc1
commit f1fe80d4
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I9NU9F

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=f1fe80d4ae3396cf3665bd6dc77f4004c1c2e9f8

--------------------------------

Adding fully unmapped pages into deferred split queue is not productive:
these pages are about to be freed or they are pinned and cannot be split
anyway.

Link: http://lkml.kernel.org/r/20190913091849.11151-1-kirill.shutemov@linux.intel.com


Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reviewed-by: Yang Shi <yang.shi@linux.alibaba.com>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Ma Wupeng <mawupeng1@huawei.com>