diff options
| author | Huaixin Chang | 2020-04-25 18:52:48 +0800 |
|---|---|---|
| committer | Peter Zijlstra | 2020-05-19 20:34:14 +0200 |
| commit | d505b8af58912ae1e1a211fabc9995b19bd40828 (patch) | |
| tree | d3eb4c4bd5d8670ee6aaaa56993a8ed366160de7 /kernel/sched/core.c | |
| parent | dbe9337109c2705f08e6a00392f991eb2d2570a5 (diff) | |
sched: Defend cfs and rt bandwidth quota against overflow
When users write some huge number into cpu.cfs_quota_us or
cpu.rt_runtime_us, overflow might happen during to_ratio() shifts of
schedulable checks.
to_ratio() could be altered to avoid unnecessary internal overflow, but
min_cfs_quota_period is less than 1 << BW_SHIFT, so a cutoff would still
be needed. Set a cap MAX_BW for cfs_quota_us and rt_runtime_us to
prevent overflow.
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>
Link: https://lkml.kernel.org/r/20200425105248.60093-1-changhuaixin@linux.alibaba.com
Diffstat (limited to 'kernel/sched/core.c')
| -rw-r--r-- | kernel/sched/core.c | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 74fb89b5ce3e..fa905b6daafa 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -7379,6 +7379,8 @@ static DEFINE_MUTEX(cfs_constraints_mutex); const u64 max_cfs_quota_period = 1 * NSEC_PER_SEC; /* 1s */ static const u64 min_cfs_quota_period = 1 * NSEC_PER_MSEC; /* 1ms */ +/* More than 203 days if BW_SHIFT equals 20. */ +static const u64 max_cfs_runtime = MAX_BW * NSEC_PER_USEC; static int __cfs_schedulable(struct task_group *tg, u64 period, u64 runtime); @@ -7407,6 +7409,12 @@ static int tg_set_cfs_bandwidth(struct task_group *tg, u64 period, u64 quota) 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(). */ |