sched/fair: Fix CFS bandwidth hrtimer expiry type

stable inclusion
from linux-4.19.199
commit aa36bd8fc187f513af2d250b82a3c913053ceaf1

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

[ Upstream commit 72d0ad7c ]

The time remaining until expiry of the refresh_timer can be negative.
Casting the type to an unsigned 64-bit value will cause integer
underflow, making the runtime_refresh_within return false instead of
true. These situations are rare, but they do happen.

This does not cause user-facing issues or errors; other than
possibly unthrottling cfs_rq's using runtime from the previous period(s),
making the CFS bandwidth enforcement less strict in those (special)
situations.

Signed-off-by: Odin Ugedal <odin@uged.al>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Ben Segall <bsegall@google.com>
Link: https://lore.kernel.org/r/20210629121452.18429-1-odin@uged.al


Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>