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[2620:137:e000::1:20]) by mx.google.com with ESMTP id dm5-20020a170907948500b0077ef3eece57si7797661ejc.144.2022.10.31.05.33.03; Mon, 31 Oct 2022 05:33:29 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=fail (p=QUARANTINE sp=QUARANTINE dis=NONE) header.from=huawei.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231343AbiJaMWw (ORCPT + 99 others); Mon, 31 Oct 2022 08:22:52 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48772 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231336AbiJaMWt (ORCPT ); Mon, 31 Oct 2022 08:22:49 -0400 Received: from szxga02-in.huawei.com (szxga02-in.huawei.com [45.249.212.188]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id F2574F039 for ; Mon, 31 Oct 2022 05:22:15 -0700 (PDT) Received: from dggpeml500026.china.huawei.com (unknown [172.30.72.56]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4N1Bwv2Wv0zVjBx; Mon, 31 Oct 2022 20:17:19 +0800 (CST) Received: from dggpeml500018.china.huawei.com (7.185.36.186) by dggpeml500026.china.huawei.com (7.185.36.106) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.31; Mon, 31 Oct 2022 20:22:14 +0800 Received: from huawei.com (10.67.174.191) by dggpeml500018.china.huawei.com (7.185.36.186) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.31; Mon, 31 Oct 2022 20:22:13 +0800 From: Zhang Qiao To: , , , CC: , , , , , , , , Subject: [PATCH next 2/2] sched: Fix sched_child_runs_first Date: Mon, 31 Oct 2022 20:51:13 +0800 Message-ID: <20221031125113.72980-3-zhangqiao22@huawei.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20221031125113.72980-1-zhangqiao22@huawei.com> References: <20221031125113.72980-1-zhangqiao22@huawei.com> MIME-Version: 1.0 X-Originating-IP: [10.67.174.191] X-ClientProxiedBy: dggems703-chm.china.huawei.com (10.3.19.180) To dggpeml500018.china.huawei.com (7.185.36.186) X-CFilter-Loop: Reflected X-Spam-Status: No, score=-4.2 required=5.0 tests=BAYES_00,RCVD_IN_DNSWL_MED, SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1748206469354949744?= X-GMAIL-MSGID: =?utf-8?q?1748206469354949744?= There are two cases that the sched_child_runs_first maybe not work fine: 1) when call clone3() with CLONE_INTO_CGROUP flags, will creating the child task into a cgroup different from the parent's cgroup, so that child and parent's cfs_rq is diffent. 2) Assign a different cpu to the new task when fork balancing. Above two case, the child and the parent will attach to different cpu and cfs_rq. At this time, we can't swap the child and parent's vruntime, and i think only do swap vruntime when the parent and child in the same cfs_rq. This patch will add the cfs_rq check before swap vruntime. Signed-off-by: Zhang Qiao --- kernel/sched/fair.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 34845d425180..6061ceb1b7cb 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -11612,7 +11612,9 @@ static void task_fork_fair(struct task_struct *p) } place_entity(cfs_rq, se, 1); - if (sysctl_sched_child_runs_first && curr && entity_before(curr, se)) { + if (sysctl_sched_child_runs_first && + cfs_rq == task_cfs_rq(current) && + curr && entity_before(curr, se)) { /* * Upon rescheduling, sched_class::put_prev_task() will place * 'current' within the tree based on its new key value.