From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.7 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, UNPARSEABLE_RELAY,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9E4FAC54FCB for ; Mon, 20 Apr 2020 02:45:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 80A242064A for ; Mon, 20 Apr 2020 02:45:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726161AbgDTCpb (ORCPT ); Sun, 19 Apr 2020 22:45:31 -0400 Received: from out30-56.freemail.mail.aliyun.com ([115.124.30.56]:59378 "EHLO out30-56.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726099AbgDTCpb (ORCPT ); Sun, 19 Apr 2020 22:45:31 -0400 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R181e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e04407;MF=changhuaixin@linux.alibaba.com;NM=1;PH=DS;RN=8;SR=0;TI=SMTPD_---0Tw0EWxD_1587350678; Received: from localhost(mailfrom:changhuaixin@linux.alibaba.com fp:SMTPD_---0Tw0EWxD_1587350678) by smtp.aliyun-inc.com(127.0.0.1); Mon, 20 Apr 2020 10:44:42 +0800 From: Huaixin Chang To: linux-kernel@vger.kernel.org Cc: peterz@infradead.org, mingo@redhat.com, bsegall@google.com, chiluk+linux@indeed.com, vincent.guittot@linaro.org, pauld@redhead.com, Huaixin Chang Subject: [PATCH 1/2] sched: Defend cfs and rt bandwidth quota against overflow Date: Mon, 20 Apr 2020 10:44:20 +0800 Message-Id: <20200420024421.22442-2-changhuaixin@linux.alibaba.com> X-Mailer: git-send-email 2.14.4.44.g2045bb6 In-Reply-To: <20200420024421.22442-1-changhuaixin@linux.alibaba.com> References: <20200420024421.22442-1-changhuaixin@linux.alibaba.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. Signed-off-by: Huaixin Chang --- 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 3a61a3b8eaa9..f0a74e35c3f0 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -7390,6 +7390,8 @@ 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_USEC * NSEC_PER_USEC; static int __cfs_schedulable(struct task_group *tg, u64 period, u64 runtime); @@ -7417,6 +7419,12 @@ 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 df11d88c9895..f5eea19d68c4 100644 --- a/kernel/sched/rt.c +++ b/kernel/sched/rt.c @@ -2569,6 +2569,9 @@ 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) { @@ -2585,6 +2588,12 @@ 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); err = __rt_schedulable(tg, rt_period, rt_runtime); if (err) diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index db3a57675ccf..6f6b7f545557 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -1918,6 +1918,8 @@ extern void init_dl_inactive_task_timer(struct sched_dl_entity *dl_se); #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); -- 2.14.4.44.g2045bb6