From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755331AbcK2BfC (ORCPT ); Mon, 28 Nov 2016 20:35:02 -0500 Received: from mga07.intel.com ([134.134.136.100]:16695 "EHLO mga07.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754506AbcK2Be5 (ORCPT ); Mon, 28 Nov 2016 20:34:57 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.31,714,1473145200"; d="scan'208";a="1065451310" Date: Tue, 29 Nov 2016 01:34:57 +0800 From: Ye Xiaolong To: Sebastian Andrzej Siewior Cc: "Paul E. McKenney" , LKML , Stephen Rothwell , lkp@01.org Subject: Re: [lkp] [rcu] a7410f28ce: INFO: rcu_sched detected expedited stalls on CPUs/tasks: { 0-... } 25089 jiffies s: 9 root: 0x1/. Message-ID: <20161128173457.GJ2501@yexl-desktop> References: <20161109062539.GB5044@yexl-desktop> <20161128205352.gozyck5ehal6nnoc@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20161128205352.gozyck5ehal6nnoc@linutronix.de> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11/28, Sebastian Andrzej Siewior wrote: >On 2016-11-09 14:25:39 [+0800], kernel test robot wrote: >> >> FYI, we noticed the following commit: >> >> https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master >> commit a7410f28ceb566bda840b4afc278747c63383fb6 ("rcu: update: Make RCU_EXPEDITE_BOOT be the default") >> >> in testcase: boot >> >> on test machine: qemu-system-x86_64 -enable-kvm -cpu host -smp 2 -m 1G >> >> caused below changes: >> >> >> +-----------------------------------------------------------------------------------+------------+------------+ >> | | 9aa96e24ec | a7410f28ce | >> +-----------------------------------------------------------------------------------+------------+------------+ >> | boot_successes | 3 | 7 | >> | boot_failures | 17 | 17 | >> | INFO:rcu_sched_self-detected_stall_on_CPU | 17 | 14 | >> | calltrace:mark_rodata_ro | 17 | 14 | >> | INFO:rcu_sched_detected_stalls_on_CPUs/tasks | 15 | 14 | >> | INFO:rcu_sched_detected_expedited_stalls_on_CPUs/tasks:{#-...}#jiffies_s:#root:#/ | 0 | 15 | >> +-----------------------------------------------------------------------------------+------------+------------+ > >Is it correct to assume that there are RCU stalls with and without my >patch but with my patch there are also "expedited" stalls? > >> [ 38.504100] Write protecting the kernel read-only data: 47104k >> [ 38.511102] Freeing unused kernel memory: 720K (ffff88000314c000 - ffff880003200000) >> [ 38.547480] Freeing unused kernel memory: 1032K (ffff880003cfe000 - ffff880003e00000) >> [ 149.710631] INFO: rcu_sched detected expedited stalls on CPUs/tasks: { 0-... } 25089 jiffies s: 9 root: 0x1/. >> [ 149.720353] blocking rcu_node structures: > >The other testing robot reported something similar against rcu/next. >With my patch I get: > >[ 14.260226] Freeing unused kernel memory: 536K (ffff88000277a000 - ffff880002800000) >[ 14.263114] Freeing unused kernel memory: 252K (ffff8800031c1000 - ffff880003200000) >[ 35.256735] INFO: rcu_sched self-detected stall on CPU >[ 35.257565] 1-...: (6299 ticks this GP) idle=0e2/140000000000001/0 softirq=90/90 fqs=2100 last_accelerate: 0000/c973, nonlazy_posted: 0, .D >[ 35.259410] (t=6300 jiffies g=-252 c=-253 q=0) >[ 35.260106] Task dump for CPU 1: >[ 35.260608] swapper/0 R running task 0 1 0 0x00000008 >[ 35.261698] ffff880036107cc0 ffffffff81181de2 0000000000021780 ffff880036121780 >[ 35.262835] 0000000000000001 ffffffff832d7fc0 ffff880036107ce0 ffffffff8118616d >[ 35.263995] ffffffff832d7fc0 0000000000000001 ffff880036107d30 ffffffff8128b3b8 >[ 35.265131] Call Trace: >[ 35.265512] [ 35.265826] [] sched_show_task+0x102/0x180 >[ 35.266701] [] dump_cpu_task+0x4d/0x60 >[ 35.267526] [] rcu_dump_cpu_stacks+0xee/0x11b >… >[ 35.289870] INFO: rcu_sched detected stalls on CPUs/tasks: >[ 35.290500] 1-...: (6301 ticks this GP) idle=0e2/140000000000000/0 softirq=90/90 fqs=2100 last_accelerate: 0000/c97d, nonlazy_posted: 0, .D >[ 35.291834] (detected by 0, t=6310 jiffies, g=-252, c=-253, q=0) >[ 35.292505] Task dump for CPU 1: >… >[ 44.260103] INFO: rcu_sched detected expedited stalls on CPUs/tasks: { 1-... } 6784 jiffies s: 299 root: 0x2/. >[ 44.261911] blocking rcu_node structures: >[ 44.262627] Task dump for CPU 1: >[ 44.263177] swapper/0 R running task 0 1 0 0x00000008 >[ 44.264379] 0000000041b58ab3 ffffffff81249eab ffffffff81b6f150 ffffffff819468d7 >[ 44.265640] 0000000041b58ab3 ffffffff830f76b0 0000000000000297 ffffffff83d87aa0 >[ 44.266915] 000000000000c6e0 0000000000000058 0000000000000000 ffff880035547be8 >[ 44.268153] Call Trace: >[ 44.268603] [] ? trace_hardirqs_on_caller+0xdb/0x1e0 >[ 44.269708] [] ? serial8250_set_defaults+0x1a0/0x1a0 > >and without it: >[ 15.837956] Freeing unused kernel memory: 536K (ffff88000277a000 - ffff880002800000) >[ 15.841396] Freeing unused kernel memory: 252K (ffff8800031c1000 - ffff880003200000) >[ 43.070453] INFO: rcu_sched self-detected stall on CPU >[ 43.071215] 1-...: (6299 ticks this GP) idle=daa/140000000000001/0 softirq=211/211 fqs=2100 last_accelerate: 0000/d29c, nonlazy_posted: 0, .D >[ 43.072807] (t=6300 jiffies g=-91 c=-92 q=0) >[ 43.073385] Task dump for CPU 1: >[ 43.073800] swapper/0 R running task 0 1 0 0x00000008 >[ 43.074734] ffff880036107cc0 ffffffff81181de2 0000000000021780 ffff880036121780 >[ 43.075715] 0000000000000001 ffffffff832d7f80 ffff880036107ce0 ffffffff8118616d >[ 43.076691] ffffffff832d7f80 0000000000000001 ffff880036107d30 ffffffff8128b3b8 >[ 43.077668] Call Trace: >[ 43.077983] [ 43.078265] [] sched_show_task+0x102/0x180 >[ 43.079006] [] dump_cpu_task+0x4d/0x60 >… >[ 43.097862] INFO: rcu_sched detected stalls on CPUs/tasks: >[ 43.098442] 1-...: (6300 ticks this GP) idle=daa/140000000000000/0 softirq=211/211 fqs=2100 last_accelerate: 0000/d2a4, nonlazy_posted: 0, .D >[ 43.099613] (detected by 0, t=6308 jiffies, g=-91, c=-92, q=0) >[ 43.100180] Task dump for CPU 1: >[ 43.100487] swapper/0 R running task 0 1 0 0x00000008 >[ 43.101171] ffffffff83d86c40 1ffff10006aa8f67 0000000500000058 0000000041b58ab3 >[ 43.101912] ffffffff8316ae78 ffffffff81b6f150 ffffffff819468d7 0000000041b58ab3 >[ 43.102657] ffffffff830f76b0 ffffffff81946830 ffff103000000020 ffff880000000020 >[ 43.103395] Call Trace: >[ 43.103647] [] ? serial8250_set_defaults+0x1a0/0x1a0 >[ 43.104272] [] ? sprintf+0xa7/0xd0 > >So it looks to me that the problem has been always there but the >additional "expedited" part in the INFO message was the reason to create >the report. Thanks for the explanation, we'll ignore this kind of reports. And sorry for the noise. Thanks, Xiaolong > >Sebastian