From 5a6d6a6ccb5f48ca8cf7c6d64ff83fd9c7999390 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 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 --- 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 c0216ef..fac5b2f 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -5159,6 +5159,8 @@ 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); @@ -5188,8 +5190,6 @@ 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; -- 2.7.4