From patchwork Thu Apr 16 13:22:50 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg KH X-Patchwork-Id: 227886 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=-6.8 required=3.0 tests=DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI, SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,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 98194C2BB55 for ; Thu, 16 Apr 2020 13:38:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 73D2F221F4 for ; Thu, 16 Apr 2020 13:38:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1587044292; bh=HLGjj7h3WyvaDbSqmdm6oGvafQSOOqJMpGqMCWrwNTY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=gosC36a4K/hGMREHCit2/3L/krTF/wlySM3pVtVU+Ep0uJkBQ3fLPbKZaBGQ36jji JaSqQ05p+cDYBLytWUuqtTmgXIof7H60DpsJBdhikl1QPFm2zM0OepTiVDcc+UV5Yq +eDe9uV7PDvoThuhlqkE8lVMydnl+UmNZL02O9Mk= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2897660AbgDPNiK (ORCPT ); Thu, 16 Apr 2020 09:38:10 -0400 Received: from mail.kernel.org ([198.145.29.99]:50548 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2897637AbgDPNiG (ORCPT ); Thu, 16 Apr 2020 09:38:06 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id E4E3822201; Thu, 16 Apr 2020 13:38:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1587044286; bh=HLGjj7h3WyvaDbSqmdm6oGvafQSOOqJMpGqMCWrwNTY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=nQeVuqSxGeEpCUGJ9jZBirDRvvMJCrwmGuivOqgpY8bsKEnnYajLZSH6TAQNxSARu 5wEuOVmQovddhA8sw+rcs07Mry2mIk35wTZsGy5uMmbvJxo/6XAh4kywnu2FeB0kLm E8Zwlx+Uh+Cjqx0UYR8ugo2BBNOEd0CmZeyOp4d8= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Christian Borntraeger , Vincent Guittot , "Peter Zijlstra (Intel)" , Dietmar Eggemann Subject: [PATCH 5.5 119/257] sched/fair: Fix enqueue_task_fair warning Date: Thu, 16 Apr 2020 15:22:50 +0200 Message-Id: <20200416131341.177449306@linuxfoundation.org> X-Mailer: git-send-email 2.26.1 In-Reply-To: <20200416131325.891903893@linuxfoundation.org> References: <20200416131325.891903893@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Vincent Guittot commit fe61468b2cbc2b7ce5f8d3bf32ae5001d4c434e9 upstream. When a cfs rq is throttled, the latter and its child are removed from the leaf list but their nr_running is not changed which includes staying higher than 1. When a task is enqueued in this throttled branch, the cfs rqs must be added back in order to ensure correct ordering in the list but this can only happens if nr_running == 1. When cfs bandwidth is used, we call unconditionnaly list_add_leaf_cfs_rq() when enqueuing an entity to make sure that the complete branch will be added. Similarly unthrottle_cfs_rq() can stop adding cfs in the list when a parent is throttled. Iterate the remaining entity to ensure that the complete branch will be added in the list. Reported-by: Christian Borntraeger Signed-off-by: Vincent Guittot Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Dietmar Eggemann Tested-by: Christian Borntraeger Tested-by: Dietmar Eggemann Cc: stable@vger.kernel.org Cc: stable@vger.kernel.org #v5.1+ Link: https://lkml.kernel.org/r/20200306135257.25044-1-vincent.guittot@linaro.org Signed-off-by: Greg Kroah-Hartman --- kernel/sched/fair.c | 26 ++++++++++++++++++++++---- 1 file changed, 22 insertions(+), 4 deletions(-) --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -3943,6 +3943,7 @@ static inline void check_schedstat_requi #endif } +static inline bool cfs_bandwidth_used(void); /* * MIGRATION @@ -4021,10 +4022,16 @@ enqueue_entity(struct cfs_rq *cfs_rq, st __enqueue_entity(cfs_rq, se); se->on_rq = 1; - if (cfs_rq->nr_running == 1) { + /* + * When bandwidth control is enabled, cfs might have been removed + * because of a parent been throttled but cfs->nr_running > 1. Try to + * add it unconditionnally. + */ + if (cfs_rq->nr_running == 1 || cfs_bandwidth_used()) list_add_leaf_cfs_rq(cfs_rq); + + if (cfs_rq->nr_running == 1) check_enqueue_throttle(cfs_rq); - } } static void __clear_buddies_last(struct sched_entity *se) @@ -4605,11 +4612,22 @@ void unthrottle_cfs_rq(struct cfs_rq *cf break; } - assert_list_leaf_cfs_rq(rq); - if (!se) add_nr_running(rq, task_delta); + /* + * The cfs_rq_throttled() breaks in the above iteration can result in + * incomplete leaf list maintenance, resulting in triggering the + * assertion below. + */ + for_each_sched_entity(se) { + cfs_rq = cfs_rq_of(se); + + list_add_leaf_cfs_rq(cfs_rq); + } + + assert_list_leaf_cfs_rq(rq); + /* Determine whether we need to wake up potentially idle CPU: */ if (rq->curr == rq->idle && rq->cfs.nr_running) resched_curr(rq);