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=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,UNPARSEABLE_RELAY,USER_AGENT_MUTT 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 7AE8AC43381 for ; Tue, 12 Mar 2019 07:33:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5017E2147C for ; Tue, 12 Mar 2019 07:33:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727380AbfCLHdx (ORCPT ); Tue, 12 Mar 2019 03:33:53 -0400 Received: from out30-42.freemail.mail.aliyun.com ([115.124.30.42]:51902 "EHLO out30-42.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726218AbfCLHdx (ORCPT ); Tue, 12 Mar 2019 03:33:53 -0400 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R171e4;CH=green;DM=||false|;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01f04455;MF=aaron.lu@linux.alibaba.com;NM=1;PH=DS;RN=14;SR=0;TI=SMTPD_---0TMXFWBE_1552376019; Received: from h07e11201.sqa.eu95(mailfrom:aaron.lu@linux.alibaba.com fp:SMTPD_---0TMXFWBE_1552376019) by smtp.aliyun-inc.com(127.0.0.1); Tue, 12 Mar 2019 15:33:46 +0800 Date: Tue, 12 Mar 2019 15:33:39 +0800 From: Aaron Lu To: Greg Kerr Cc: Subhra Mazumdar , Aubrey Li , 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 Subject: Re: [RFC][PATCH 00/16] sched: Core scheduling Message-ID: <20190312073338.GA7958@h07e11201.sqa.eu95> References: <20190218165620.383905466@infradead.org> <20190222124544.GY9565@techsingularity.net> <14a9adf7-9b50-1dfa-0c35-d04e976081c2@oracle.com> <19d5d492-a4c1-b3c8-cae4-da2fdfcb872b@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Mar 11, 2019 at 05:20:19PM -0700, Greg Kerr wrote: > On Mon, Mar 11, 2019 at 4:36 PM Subhra Mazumdar > wrote: > > > > > > 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. > > Is this panic below, which occurs when I tag the first process, > related or known? If not, I will debug it tomorrow. > > [ 46.831828] BUG: unable to handle kernel NULL pointer dereference > at 0000000000000000 > [ 46.831829] core sched enabled > [ 46.834261] #PF error: [WRITE] > [ 46.834899] PGD 0 P4D 0 > [ 46.835438] Oops: 0002 [#1] SMP PTI > [ 46.836158] CPU: 0 PID: 11 Comm: migration/0 Not tainted > 5.0.0everyday-glory-03949-g2d8fdbb66245-dirty #7 > [ 46.838206] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), > BIOS 1.10.2-1 04/01/2014 Probably due to SMT not enabled for this qemu setup. rq->core can be NULL for cpu0: sched_cpu_starting() won't be called for CPU0 and since it doesn't have any siblings, its rq->core remains un-initialized(NULL). > [ 46.839844] RIP: 0010:_raw_spin_lock+0x7/0x20 > [ 46.840448] Code: 00 00 00 65 81 05 25 ca 5c 51 00 02 00 00 31 c0 > ba ff 00 00 00 f0 0f b1 17 74 05 e9 93 80 46 ff f3 c3 90 31 c0 ba 01 > 00 00 00 0f b1 17 74 07 89 c6 e9 1c 6e 46 ff f3 c3 66 2e 0f 1f 84 > 00 00 > [ 46.843000] RSP: 0018:ffffb9d300cabe38 EFLAGS: 00010046 > [ 46.843744] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000004 > [ 46.844709] RDX: 0000000000000001 RSI: ffffffffaea435ae RDI: 0000000000000000 > [ 46.845689] RBP: ffffb9d300cabed8 R08: 0000000000000000 R09: 0000000000020800 > [ 46.846651] R10: ffffffffaf603ea0 R11: 0000000000000001 R12: ffffffffaf6576c0 > [ 46.847619] R13: ffff9a57366c8000 R14: ffff9a5737401300 R15: ffffffffade868f0 > [ 46.848584] FS: 0000000000000000(0000) GS:ffff9a5737a00000(0000) > knlGS:0000000000000000 > [ 46.849680] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > [ 46.850455] CR2: 0000000000000000 CR3: 00000001d36fa000 CR4: 00000000000006f0 > [ 46.851415] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > [ 46.852371] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > [ 46.853326] Call Trace: > [ 46.853678] __schedule+0x139/0x11f0 > [ 46.854167] ? cpumask_next+0x16/0x20 > [ 46.854668] ? cpu_stop_queue_work+0xc0/0xc0 > [ 46.855252] ? sort_range+0x20/0x20 > [ 46.855742] schedule+0x4e/0x60 > [ 46.856171] smpboot_thread_fn+0x12a/0x160 > [ 46.856725] kthread+0x112/0x120 > [ 46.857164] ? kthread_stop+0xf0/0xf0 > [ 46.857661] ret_from_fork+0x35/0x40 > [ 46.858146] Modules linked in: > [ 46.858562] CR2: 0000000000000000 > [ 46.859022] ---[ end trace e9fff08f17bfd2be ]---