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 X-Spam-Level: X-Spam-Status: No, score=-4.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_PASS 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 14306C43381 for ; Mon, 11 Mar 2019 23:36:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CA3FE2087C for ; Mon, 11 Mar 2019 23:36:22 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b="lRJmdFas" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726436AbfCKXgV (ORCPT ); Mon, 11 Mar 2019 19:36:21 -0400 Received: from aserp2130.oracle.com ([141.146.126.79]:53864 "EHLO aserp2130.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725850AbfCKXgU (ORCPT ); Mon, 11 Mar 2019 19:36:20 -0400 Received: from pps.filterd (aserp2130.oracle.com [127.0.0.1]) by aserp2130.oracle.com (8.16.0.27/8.16.0.27) with SMTP id x2BNXwOw074888; Mon, 11 Mar 2019 23:35:58 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=subject : from : to : cc : references : message-id : date : mime-version : in-reply-to : content-type : content-transfer-encoding; s=corp-2018-07-02; bh=NJKDtsh5YrM8x5tUkycex/CSPhouA9bJRC3diCVnwtc=; b=lRJmdFas0b8kxWuc7L2qTZtKtcmEBK3xWcHg2atb1NWKF8NRqjuWoe6mgcyb+8JnnS/l FcIbJ0zp/JDx+kNrLLu2NIyLuvn8u5EuPqmjbZjYLE7teni+z0HPtfD3yiSie1Xtpgao 454aTNhlz66bkj7+v1CC3lWQoGq2Nm83J79SgJf0tfhkWYPr3QtK2aR79rDEXwFLLgzc e3M4qVvh7hmmjULeakpbk2an6Htu+bQm5Xfed6SVqvkBsDnyPCaPTlukWSIFS6uqP1VW AJcgZQpC/iNKUHIO9uSu2tPtR7mq6nxOOE//3LNDEtmn8sDOR5vjl3qp7bMTF8dbGiua QQ== Received: from aserv0021.oracle.com (aserv0021.oracle.com [141.146.126.233]) by aserp2130.oracle.com with ESMTP id 2r430ehwpw-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 11 Mar 2019 23:35:58 +0000 Received: from aserv0121.oracle.com (aserv0121.oracle.com [141.146.126.235]) by aserv0021.oracle.com (8.14.4/8.14.4) with ESMTP id x2BNZwhF027346 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 11 Mar 2019 23:35:58 GMT Received: from abhmp0012.oracle.com (abhmp0012.oracle.com [141.146.116.18]) by aserv0121.oracle.com (8.14.4/8.13.8) with ESMTP id x2BNZuMu017111; Mon, 11 Mar 2019 23:35:56 GMT Received: from [10.132.91.175] (/10.132.91.175) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Mon, 11 Mar 2019 16:35:56 -0700 Subject: Re: [RFC][PATCH 00/16] sched: Core scheduling From: Subhra Mazumdar To: Aubrey Li Cc: Mel Gorman , Peter Zijlstra , Ingo Molnar , Thomas Gleixner , Paul Turner , Tim Chen , Linux List Kernel Mailing , Linus Torvalds , Fr?d?ric Weisbecker , Kees Cook , Greg Kerr References: <20190218165620.383905466@infradead.org> <20190222124544.GY9565@techsingularity.net> <14a9adf7-9b50-1dfa-0c35-d04e976081c2@oracle.com> <19d5d492-a4c1-b3c8-cae4-da2fdfcb872b@oracle.com> Message-ID: Date: Mon, 11 Mar 2019 16:33:22 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.5.1 MIME-Version: 1.0 In-Reply-To: <19d5d492-a4c1-b3c8-cae4-da2fdfcb872b@oracle.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US X-Proofpoint-Virus-Version: vendor=nai engine=5900 definitions=9192 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1903110160 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 3/11/19 11:34 AM, Subhra Mazumdar wrote: > > On 3/10/19 9:23 PM, Aubrey Li wrote: >> On Sat, Mar 9, 2019 at 3:50 AM Subhra Mazumdar >> wrote: >>> expected. Most of the performance recovery happens in patch 15 which, >>> unfortunately, is also the one that introduces the hard lockup. >>> >> After applied Subhra's patch, the following is triggered by enabling >> core sched when a cgroup is >> under heavy load. >> > It seems you are facing some other deadlock where printk is involved. > Can you > drop the last patch (patch 16 sched: Debug bits...) and try? > > Thanks, > Subhra > Never Mind, I am seeing the same lockdep deadlock output even w/o patch 16. Btw the NULL fix had something missing, following works. --------->8------------ diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 1d0dac4..27cbc64 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -4131,7 +4131,7 @@ pick_next_entity(struct cfs_rq *cfs_rq, struct sched_entity *curr)          * Avoid running the skip buddy, if running something else can          * be done without getting too unfair. */ -       if (cfs_rq->skip == se) { +       if (cfs_rq->skip && cfs_rq->skip == se) {                 struct sched_entity *second;                 if (se == curr) { @@ -4149,13 +4149,15 @@ pick_next_entity(struct cfs_rq *cfs_rq, struct sched_entity *curr) /*          * Prefer last buddy, try to return the CPU to a preempted task. */ -       if (cfs_rq->last && wakeup_preempt_entity(cfs_rq->last, left) < 1) +       if (left && cfs_rq->last && wakeup_preempt_entity(cfs_rq->last, left) +           < 1)                 se = cfs_rq->last; /*          * Someone really wants this to run. If it's not unfair, run it. */ -       if (cfs_rq->next && wakeup_preempt_entity(cfs_rq->next, left) < 1) +       if (left && cfs_rq->next && wakeup_preempt_entity(cfs_rq->next, left) +           < 1)                 se = cfs_rq->next;         clear_buddies(cfs_rq, se); @@ -6958,6 +6960,9 @@ pick_task_fair(struct rq *rq)                 se = pick_next_entity(cfs_rq, NULL); +               if (!(se || curr)) +                       return NULL; +                 if (curr) {                         if (se && curr->on_rq) update_curr(cfs_rq);