Commit 46edfe61 authored by Zhao Wenhui's avatar Zhao Wenhui Committed by Cheng Yu
Browse files

sched/fair: limit burst to zero when cfs bandwidth is toggled off 

hulk inclusion
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I9PR8C


CVE: NA

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

sched/fair: limit burst to zero when cfs bandwidth is toggled off

When the quota value in CFS bandwidth is set to -1, that imples the
cfs bandwidth is toggled off. So the burst feature is supposed to
be disable as well.

Currently, when quota is -1, burst will not be check, so that it can be
set to almost arbitery value. Examples:
        mkdir /sys/fs/cgroup/cpu/test
        echo -1 > /sys/fs/cgroup/cpu/test/cpu.cfs_quota_us
        echo 10000000000000000 > /sys/fs/cgroup/cpu/test/cpu.cfs_burst_us

Moreover, after the burst modified by this way, quota can't be set
to any value:
        echo 100000 > cpu.cfs_quota_us
        -bash: echo: write error: Invalid argument

This patch can ensure the burst value being zero and unalterable,
when quota is set to -1.

Fixes: f4183717 ("sched/fair: Introduce the burstable CFS controller")
Signed-off-by: default avatarZhao Wenhui <zhaowenhui8@huawei.com>
Signed-off-by: default avatarCheng Yu <serein.chengyu@huawei.com>
parent ba7871ba

kernel/sched/core.c

+9 −1
Original line number Diff line number Diff line
@@ -11051,6 +11051,12 @@ static int tg_set_cfs_bandwidth(struct task_group *tg, u64 period, u64 quota, 
				     burst + quota > max_cfs_runtime))

		return -EINVAL;



	/*

	 * Ensure burst equals to zero when quota is -1.

	 */

	if (quota == RUNTIME_INF && burst)

		return -EINVAL;



	/*

	 * Prevent race between setting of cfs_rq->runtime_enabled and

	 * unthrottle_offline_cfs_rqs().
@@ -11110,8 +11116,10 @@ static int tg_set_cfs_quota(struct task_group *tg, long cfs_quota_us) 


	period = ktime_to_ns(tg->cfs_bandwidth.period);

	burst = tg->cfs_bandwidth.burst;

	if (cfs_quota_us < 0)

	if (cfs_quota_us < 0) {

		quota = RUNTIME_INF;

		burst = 0;

	}

	else if ((u64)cfs_quota_us <= U64_MAX / NSEC_PER_USEC)

		quota = (u64)cfs_quota_us * NSEC_PER_USEC;

	else