From nobody Sat Apr 11 00:44:31 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 48D64C32771 for ; Thu, 18 Aug 2022 03:46:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S243150AbiHRDqY (ORCPT ); Wed, 17 Aug 2022 23:46:24 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39714 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S243126AbiHRDqK (ORCPT ); Wed, 17 Aug 2022 23:46:10 -0400 Received: from mail-pf1-x429.google.com (mail-pf1-x429.google.com [IPv6:2607:f8b0:4864:20::429]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 88F6895680 for ; Wed, 17 Aug 2022 20:46:09 -0700 (PDT) Received: by mail-pf1-x429.google.com with SMTP id 81so418268pfz.10 for ; Wed, 17 Aug 2022 20:46:09 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bytedance-com.20210112.gappssmtp.com; s=20210112; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc; bh=w96IsTb3GQtW46GghcS8avnysfYYRuHuTPsKLYARCUM=; b=Lbo0sm4b3VCe1e81KQcnj0Uo8jxOJvs0JV470Z7MXEVfLFKMrGFdXzPO3wtGUc1Vx2 McH+g/o4Tt0J36WdBLo8DKhUTxYyXD0zOxeutkn8tjXdTcpOAOy0RpLbThn/bq3BECcU VxjKDNQDmf8jxjNSkytt+ogUAeQjXFOKiR3/N77b2q57XTHF63vFfOcOc2hNzni0JzCb VU7fNDPNef766Zf9+1vBgfmsUsjghjrfwp7uAC7rAfRREK6gOu/jgjLGcLEVcy+0Zp/Z bO+waBUkH5gohM068ET0g1BkRYrdyY28Dd8Zrzte81IkRG1dXGRQSu2RuE6BN1bdo77S MvEw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc; bh=w96IsTb3GQtW46GghcS8avnysfYYRuHuTPsKLYARCUM=; b=c5xeKkx0XR9cu/ObnTexd5vqgx0Dl7ayDQbJ6mekQxGVnpWUsSMDaJN4ipixH/2lJK SDijyXxYUiqS2Cb45XjWYQ2t4rXZPGX0s1iKlGGUq6o4BAkZODjXXBBS+ArTdLT1LL2O MQ8lPrzhiuYDdUfcLPdcFklAua3vvH15A3phvSDn9NvjIDPpT2DScfzSD1PIkm/6MljK bnE8XUuRSUYHpaEPzcadDIJ5xbq47veHpKZN6rD5qU1Geqqk3KllwqR7iGHuunw8XL10 EZF9aWba9LrpoKakkqWhOc3zgxV8LF7DSDNMDHWi80zGCE2ZKahFF//t8cGEjKj5MQV3 tkTg== X-Gm-Message-State: ACgBeo2ml8eeDcg9V/CTKhrUdzpbxGWaIrZyvCZabL8u2eTUBOOwnESw O3m7jNUkn2uztj4owECmHJpyhg== X-Google-Smtp-Source: AA6agR6a7JJX+IywiQrBnUNjn49NfgqaXo2Uaudj+SXY+rDDEYMjstMBGpLSoxX4YsRpnauagG6law== X-Received: by 2002:a05:6a00:21c5:b0:52b:fc9c:295b with SMTP id t5-20020a056a0021c500b0052bfc9c295bmr1201176pfj.56.1660794368842; Wed, 17 Aug 2022 20:46:08 -0700 (PDT) Received: from C02CV1DAMD6P.bytedance.net ([139.177.225.246]) by smtp.gmail.com with ESMTPSA id m11-20020a65564b000000b00419acadde52sm268700pgs.46.2022.08.17.20.46.05 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 17 Aug 2022 20:46:08 -0700 (PDT) From: Chengming Zhou To: vincent.guittot@linaro.org, dietmar.eggemann@arm.com, mingo@redhat.com, peterz@infradead.org, rostedt@goodmis.org, bsegall@google.com, vschneid@redhat.com Cc: linux-kernel@vger.kernel.org, tj@kernel.org, Chengming Zhou Subject: [PATCH v5 7/9] sched/fair: allow changing cgroup of new forked task Date: Thu, 18 Aug 2022 11:43:41 +0800 Message-Id: <20220818034343.87625-8-zhouchengming@bytedance.com> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220818034343.87625-1-zhouchengming@bytedance.com> References: <20220818034343.87625-1-zhouchengming@bytedance.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" commit 7dc603c9028e ("sched/fair: Fix PELT integrity for new tasks") introduce a TASK_NEW state and an unnessary limitation that would fail when changing cgroup of new forked task. Because at that time, we can't handle task_change_group_fair() for new forked fair task which hasn't been woken up by wake_up_new_task(), which will cause detach on an unattached task sched_avg problem. This patch delete this unnessary limitation by adding check before do detach or attach in task_change_group_fair(). So cpu_cgrp_subsys.can_attach() has nothing to do for fair tasks, only define it in #ifdef CONFIG_RT_GROUP_SCHED. Signed-off-by: Chengming Zhou --- include/linux/sched.h | 5 ++--- kernel/sched/core.c | 30 +++++++----------------------- kernel/sched/fair.c | 7 +++++++ 3 files changed, 16 insertions(+), 26 deletions(-) diff --git a/include/linux/sched.h b/include/linux/sched.h index e7b2f8a5c711..0b296e855dee 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -96,10 +96,9 @@ struct task_group; #define TASK_WAKEKILL 0x0100 #define TASK_WAKING 0x0200 #define TASK_NOLOAD 0x0400 -#define TASK_NEW 0x0800 /* RT specific auxilliary flag to mark RT lock waiters */ -#define TASK_RTLOCK_WAIT 0x1000 -#define TASK_STATE_MAX 0x2000 +#define TASK_RTLOCK_WAIT 0x0800 +#define TASK_STATE_MAX 0x1000 =20 /* Convenience macros for the sake of set_current_state: */ #define TASK_KILLABLE (TASK_WAKEKILL | TASK_UNINTERRUPTIBLE) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 8e3f1c3f0b2c..157f7461a08a 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -4550,11 +4550,11 @@ int sched_fork(unsigned long clone_flags, struct ta= sk_struct *p) { __sched_fork(clone_flags, p); /* - * We mark the process as NEW here. This guarantees that + * We mark the process as running here. This guarantees that * nobody will actually run it, and a signal or other external * event cannot wake it up and insert it on the runqueue either. */ - p->__state =3D TASK_NEW; + p->__state =3D TASK_RUNNING; =20 /* * Make sure we do not leak PI boosting priority to the child. @@ -4672,7 +4672,6 @@ void wake_up_new_task(struct task_struct *p) struct rq *rq; =20 raw_spin_lock_irqsave(&p->pi_lock, rf.flags); - WRITE_ONCE(p->__state, TASK_RUNNING); #ifdef CONFIG_SMP /* * Fork balancing, do it here and not earlier because: @@ -10290,36 +10289,19 @@ static void cpu_cgroup_css_free(struct cgroup_sub= sys_state *css) sched_unregister_group(tg); } =20 +#ifdef CONFIG_RT_GROUP_SCHED static int cpu_cgroup_can_attach(struct cgroup_taskset *tset) { struct task_struct *task; struct cgroup_subsys_state *css; - int ret =3D 0; =20 cgroup_taskset_for_each(task, css, tset) { -#ifdef CONFIG_RT_GROUP_SCHED if (!sched_rt_can_attach(css_tg(css), task)) return -EINVAL; -#endif - /* - * Serialize against wake_up_new_task() such that if it's - * running, we're sure to observe its full state. - */ - raw_spin_lock_irq(&task->pi_lock); - /* - * Avoid calling sched_move_task() before wake_up_new_task() - * has happened. This would lead to problems with PELT, due to - * move wanting to detach+attach while we're not attached yet. - */ - if (READ_ONCE(task->__state) =3D=3D TASK_NEW) - ret =3D -EINVAL; - raw_spin_unlock_irq(&task->pi_lock); - - if (ret) - break; } - return ret; + return 0; } +#endif =20 static void cpu_cgroup_attach(struct cgroup_taskset *tset) { @@ -11155,7 +11137,9 @@ struct cgroup_subsys cpu_cgrp_subsys =3D { .css_released =3D cpu_cgroup_css_released, .css_free =3D cpu_cgroup_css_free, .css_extra_stat_show =3D cpu_extra_stat_show, +#ifdef CONFIG_RT_GROUP_SCHED .can_attach =3D cpu_cgroup_can_attach, +#endif .attach =3D cpu_cgroup_attach, .legacy_cftypes =3D cpu_legacy_files, .dfl_cftypes =3D cpu_files, diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index eba8a64f905a..e0d34ecdabae 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -11840,6 +11840,13 @@ void init_cfs_rq(struct cfs_rq *cfs_rq) #ifdef CONFIG_FAIR_GROUP_SCHED static void task_change_group_fair(struct task_struct *p) { + /* + * We couldn't detach or attach a forked task which + * hasn't been woken up by wake_up_new_task(). + */ + if (!p->on_rq && !p->se.sum_exec_runtime) + return; + detach_task_cfs_rq(p); =20 #ifdef CONFIG_SMP --=20 2.37.2