From 9f664eda61a04701c14d3c0f6b30ee837de955f4 Mon Sep 17 00:00:00 2001 From: Huaixin Chang Date: Mon, 20 Apr 2020 10:44:21 +0800 Subject: [PATCH] sched/fair: Refill bandwidth before scaling [ Upstream commit 5a6d6a6ccb5f48ca8cf7c6d64ff83fd9c7999390 ] In order to prevent possible hardlockup of sched_cfs_period_timer() loop, loop count is introduced to denote whether to scale quota and period or not. However, scale is done between forwarding period timer and refilling cfs bandwidth runtime, which means that period timer is forwarded with old "period" while runtime is refilled with scaled "quota". Move do_sched_cfs_period_timer() before scaling to solve this. Fixes: 2e8e19226398 ("sched/fair: Limit sched_cfs_period_timer() loop to avoid hard lockup") Signed-off-by: Huaixin Chang Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Ben Segall Reviewed-by: Phil Auld Link: https://lkml.kernel.org/r/20200420024421.22442-3-changhuaixin@linux.alibaba.com Signed-off-by: Sasha Levin --- kernel/sched/fair.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 8a0e6bdba50d..2f81e4ae844e 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -4942,6 +4942,8 @@ static enum hrtimer_restart sched_cfs_period_timer(struct hrtimer *timer) if (!overrun) break; + idle = do_sched_cfs_period_timer(cfs_b, overrun, flags); + if (++count > 3) { u64 new, old = ktime_to_ns(cfs_b->period); @@ -4971,8 +4973,6 @@ static enum hrtimer_restart sched_cfs_period_timer(struct hrtimer *timer) /* reset count so we don't come right back in here */ count = 0; } - - idle = do_sched_cfs_period_timer(cfs_b, overrun, flags); } if (idle) cfs_b->period_active = 0;