cpumask: Introduce DYING mask

mainline inclusion
from mainline-v5.13-rc1
commit e40f74c5
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I6VS35

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=e40f74c535b8a0ecf3ef0388b51a34cdadb34fb5



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Introduce a cpumask that indicates (for each CPU) what direction the
CPU hotplug is currently going. Notably, it tracks rollbacks. Eg. when
an up fails and we do a roll-back down, it will accurately reflect the
direction.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Valentin Schneider <valentin.schneider@arm.com>
Link: https://lkml.kernel.org/r/20210310150109.151441252@infradead.org


Signed-off-by: Zeng Heng <zengheng4@huawei.com>