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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 66896C35271 for ; Mon, 24 Jan 2022 19:15:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230297AbiAXTPl (ORCPT ); Mon, 24 Jan 2022 14:15:41 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48004 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1344886AbiAXTNQ (ORCPT ); Mon, 24 Jan 2022 14:13:16 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E8DE5C0604EE; Mon, 24 Jan 2022 11:04:56 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id A4AE3B8122F; Mon, 24 Jan 2022 19:04:55 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id A7AA8C340E5; Mon, 24 Jan 2022 19:04:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1643051094; bh=Itpp8NO44b1xZ6LMPWzH1bUZjsSx4L43K2IPFVftaNI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=HImC4TNR9rX1ohiXf+RZAtbk/S6aQsCFThiAgfQN8qFcmQk6vnACak4phK069is9o Z6gHuIicRvMnonlUI0679jsgpvWts7OSZ4siV8pUOFCsJzBjyEoiomk5gf5f7crdbr Y56pF7UZJfsQeMnj/2kQJbXwDzmnDd3aZIiwQgjI= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Hulk Robot , Li Hua , "Peter Zijlstra (Intel)" , Sasha Levin Subject: [PATCH 4.14 053/186] sched/rt: Try to restart rt period timer when rt runtime exceeded Date: Mon, 24 Jan 2022 19:42:08 +0100 Message-Id: <20220124183938.834983282@linuxfoundation.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20220124183937.101330125@linuxfoundation.org> References: <20220124183937.101330125@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Li Hua [ Upstream commit 9b58e976b3b391c0cf02e038d53dd0478ed3013c ] When rt_runtime is modified from -1 to a valid control value, it may cause the task to be throttled all the time. Operations like the following will trigger the bug. E.g: 1. echo -1 > /proc/sys/kernel/sched_rt_runtime_us 2. Run a FIFO task named A that executes while(1) 3. echo 950000 > /proc/sys/kernel/sched_rt_runtime_us When rt_runtime is -1, The rt period timer will not be activated when task A enqueued. And then the task will be throttled after setting rt_runtime to 950,000. The task will always be throttled because the rt period timer is not activated. Fixes: d0b27fa77854 ("sched: rt-group: synchonised bandwidth period") Reported-by: Hulk Robot Signed-off-by: Li Hua Signed-off-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/20211203033618.11895-1-hucool.lihua@huawei.com Signed-off-by: Sasha Levin --- kernel/sched/rt.c | 23 ++++++++++++++++++----- 1 file changed, 18 insertions(+), 5 deletions(-) diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c index cc7dd1aaf08e3..c093bb0f52eb1 100644 --- a/kernel/sched/rt.c +++ b/kernel/sched/rt.c @@ -52,11 +52,8 @@ void init_rt_bandwidth(struct rt_bandwidth *rt_b, u64 period, u64 runtime) rt_b->rt_period_timer.function = sched_rt_period_timer; } -static void start_rt_bandwidth(struct rt_bandwidth *rt_b) +static inline void do_start_rt_bandwidth(struct rt_bandwidth *rt_b) { - if (!rt_bandwidth_enabled() || rt_b->rt_runtime == RUNTIME_INF) - return; - raw_spin_lock(&rt_b->rt_runtime_lock); if (!rt_b->rt_period_active) { rt_b->rt_period_active = 1; @@ -74,6 +71,14 @@ static void start_rt_bandwidth(struct rt_bandwidth *rt_b) raw_spin_unlock(&rt_b->rt_runtime_lock); } +static void start_rt_bandwidth(struct rt_bandwidth *rt_b) +{ + if (!rt_bandwidth_enabled() || rt_b->rt_runtime == RUNTIME_INF) + return; + + do_start_rt_bandwidth(rt_b); +} + void init_rt_rq(struct rt_rq *rt_rq) { struct rt_prio_array *array; @@ -982,13 +987,17 @@ static void update_curr_rt(struct rq *rq) for_each_sched_rt_entity(rt_se) { struct rt_rq *rt_rq = rt_rq_of_se(rt_se); + int exceeded; if (sched_rt_runtime(rt_rq) != RUNTIME_INF) { raw_spin_lock(&rt_rq->rt_runtime_lock); rt_rq->rt_time += delta_exec; - if (sched_rt_runtime_exceeded(rt_rq)) + exceeded = sched_rt_runtime_exceeded(rt_rq); + if (exceeded) resched_curr(rq); raw_spin_unlock(&rt_rq->rt_runtime_lock); + if (exceeded) + do_start_rt_bandwidth(sched_rt_bandwidth(rt_rq)); } } } @@ -2629,8 +2638,12 @@ static int sched_rt_global_validate(void) static void sched_rt_do_global(void) { + unsigned long flags; + + raw_spin_lock_irqsave(&def_rt_bandwidth.rt_runtime_lock, flags); def_rt_bandwidth.rt_runtime = global_rt_runtime(); def_rt_bandwidth.rt_period = ns_to_ktime(global_rt_period()); + raw_spin_unlock_irqrestore(&def_rt_bandwidth.rt_runtime_lock, flags); } int sched_rt_handler(struct ctl_table *table, int write, -- 2.34.1