mm: add a helper function to check may oom condition

Use helper function to check if we need to deal with oom condition.

Signed-off-by: Qiang Huang <h.huangqiang@huawei.com>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --cc include/linux/oom.h
Simple merge

diff --cc mm/memcontrol.c
Simple merge

diff --cc mm/page_alloc.c
Simple merge