From: Huaixin Chang <changhuaixin(a)linux.alibaba.com>
anolis inclusion
from anolis_master
commit 9d168f216486333f24aa1b33706eddf3b13d7228
category: performance
bugzilla: NA
CVE: NA
---------------------------
Kernel limitation on cpu.cfs_quota_us is insufficient. Some large
numbers might cause overflow in to_ratio() calculation and produce
unexpected results.
For example, if we make two cpu cgroups and then write a reasonable
value and a large value into child's and parent's cpu.cfs_quota_us. This
will cause a write error.
cd /sys/fs/cgroup/cpu
mkdir parent; mkdir parent/child
echo 8000 > parent/child/cpu.cfs_quota_us
# 17592186044416 is (1UL << 44)
echo 17592186044416 > parent/cpu.cfs_quota_us
In this case, quota will overflow and thus fail the __cfs_schedulable
check. Similar overflow also affects rt bandwidth.
Burstable CFS bandwidth controller will also benefit from limiting
quota.
Change-Id: I0f89d1f26b168c5cfa041e886395c7f3068114ae
Reviewed-by: Shanpei Chen <shanpeic(a)linux.alibaba.com>
Signed-off-by: Huaixin Chang <changhuaixin(a)linux.alibaba.com>
Signed-off-by: Zhengyuan Liu <liuzhengyuan(a)kylinos.cn>
---
kernel/sched/core.c | 8 ++++++++
kernel/sched/rt.c | 9 +++++++++
kernel/sched/sched.h | 2 ++
3 files changed, 19 insertions(+)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 36d7422da0ac..51fdd30f188a 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -6679,6 +6679,8 @@ static DEFINE_MUTEX(cfs_constraints_mutex);
const u64 max_cfs_quota_period = 1 * NSEC_PER_SEC; /* 1s */
const u64 min_cfs_quota_period = 1 * NSEC_PER_MSEC; /* 1ms */
+/* More than 203 days if BW_SHIFT equals 20. */
+const u64 max_cfs_runtime = MAX_BW_USEC * NSEC_PER_USEC;
static int __cfs_schedulable(struct task_group *tg, u64 period, u64 runtime);
@@ -6706,6 +6708,12 @@ static int tg_set_cfs_bandwidth(struct task_group *tg, u64 period, u64 quota)
if (period > max_cfs_quota_period)
return -EINVAL;
+ /*
+ * Bound quota to defend quota against overflow during bandwidth shift.
+ */
+ if (quota != RUNTIME_INF && quota > max_cfs_runtime)
+ return -EINVAL;
+
/*
* Prevent race between setting of cfs_rq->runtime_enabled and
* unthrottle_offline_cfs_rqs().
diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
index 301ba04d9130..f31e0aaf1f43 100644
--- a/kernel/sched/rt.c
+++ b/kernel/sched/rt.c
@@ -2518,6 +2518,9 @@ static int __rt_schedulable(struct task_group *tg, u64 period, u64 runtime)
return ret;
}
+/* More than 203 days if BW_SHIFT equals 20. */
+static const u64 max_rt_runtime = MAX_BW_USEC * NSEC_PER_USEC;
+
static int tg_set_rt_bandwidth(struct task_group *tg,
u64 rt_period, u64 rt_runtime)
{
@@ -2534,6 +2537,12 @@ static int tg_set_rt_bandwidth(struct task_group *tg,
if (rt_period == 0)
return -EINVAL;
+ /*
+ * Bound quota to defend quota against overflow during bandwidth shift.
+ */
+ if (rt_runtime != RUNTIME_INF && rt_runtime > max_rt_runtime)
+ return -EINVAL;
+
mutex_lock(&rt_constraints_mutex);
read_lock(&tasklist_lock);
err = __rt_schedulable(tg, rt_period, rt_runtime);
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index ae3068153093..f3808a49ce48 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -1732,6 +1732,8 @@ extern void init_dl_rq_bw_ratio(struct dl_rq *dl_rq);
#define BW_SHIFT 20
#define BW_UNIT (1 << BW_SHIFT)
#define RATIO_SHIFT 8
+#define MAX_BW_BITS (64 - BW_SHIFT)
+#define MAX_BW_USEC ((1UL << MAX_BW_BITS) - 1)
unsigned long to_ratio(u64 period, u64 runtime);
extern void init_entity_runnable_average(struct sched_entity *se);
--
2.25.1