From: Huaixin Chang changhuaixin@linux.alibaba.com
mainline inclusion from mainline-v6.5-rc7 commit 5a6d6a6ccb5f48ca8cf7c6d64ff83fd9c7999390 category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I8EUCE CVE: NA
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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 changhuaixin@linux.alibaba.com Signed-off-by: Peter Zijlstra (Intel) peterz@infradead.org Reviewed-by: Ben Segall bsegall@google.com Reviewed-by: Phil Auld pauld@redhat.com Link: https://lkml.kernel.org/r/20200420024421.22442-3-changhuaixin@linux.alibaba.... Signed-off-by: Xia Fukun xiafukun@huawei.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 1c78e2f29901..ccd2a060c2df 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -5099,6 +5099,8 @@ 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);
@@ -5128,8 +5130,6 @@ 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;