From nobody Thu Apr 9 00:19:18 2026 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 D57D0C433FE for ; Thu, 3 Nov 2022 11:38:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230402AbiKCLiv (ORCPT ); Thu, 3 Nov 2022 07:38:51 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50774 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231462AbiKCLi1 (ORCPT ); Thu, 3 Nov 2022 07:38:27 -0400 Received: from szxga08-in.huawei.com (szxga08-in.huawei.com [45.249.212.255]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2713B1209D for ; Thu, 3 Nov 2022 04:38:25 -0700 (PDT) Received: from dggpeml500022.china.huawei.com (unknown [172.30.72.55]) by szxga08-in.huawei.com (SkyGuard) with ESMTP id 4N31wV6FFmz15MKj; Thu, 3 Nov 2022 19:38:18 +0800 (CST) Received: from dggpeml500018.china.huawei.com (7.185.36.186) by dggpeml500022.china.huawei.com (7.185.36.66) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.31; Thu, 3 Nov 2022 19:38:23 +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; Thu, 3 Nov 2022 19:38:23 +0800 From: Zhang Qiao To: , , , , CC: , , , , , , , , Zhang Qiao Subject: [PATCH v2 2/2] sched: Fix sched_child_runs_first Date: Thu, 3 Nov 2022 20:07:20 +0800 Message-ID: <20221103120720.39873-3-zhangqiao22@huawei.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20221103120720.39873-1-zhangqiao22@huawei.com> References: <20221103120720.39873-1-zhangqiao22@huawei.com> MIME-Version: 1.0 X-Originating-IP: [10.67.174.191] X-ClientProxiedBy: dggems701-chm.china.huawei.com (10.3.19.178) To dggpeml500018.china.huawei.com (7.185.36.186) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" 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); =20 - if (sysctl_sched_child_runs_first && curr && entity_before(curr, se)) { + if (sysctl_sched_child_runs_first && + cfs_rq =3D=3D 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. --=20 2.17.1