Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751625AbaLOGdl (ORCPT ); Mon, 15 Dec 2014 01:33:41 -0500 Received: from e34.co.us.ibm.com ([32.97.110.152]:34816 "EHLO e34.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751070AbaLOGdk (ORCPT ); Mon, 15 Dec 2014 01:33:40 -0500 Date: Sun, 14 Dec 2014 22:33:31 -0800 From: "Paul E. McKenney" To: Sasha Levin Cc: Ingo Molnar , David Lang , Linus Torvalds , Dave Jones , Chris Mason , Mike Galbraith , Peter Zijlstra , =?iso-8859-1?Q?D=E2niel?= Fraga , Linux Kernel Mailing List Subject: Re: frequent lockups in 3.18rc4 Message-ID: <20141215063331.GL5310@linux.vnet.ibm.com> Reply-To: paulmck@linux.vnet.ibm.com References: <20141212203417.GE25340@linux.vnet.ibm.com> <548B5CEC.1040607@oracle.com> <20141213083055.GI32572@gmail.com> <548C60FF.9020607@oracle.com> <20141213180752.GI25340@linux.vnet.ibm.com> <20141214175007.GA6927@linux.vnet.ibm.com> <548E214D.6040706@oracle.com> <20141215001123.GK5310@linux.vnet.ibm.com> <548E374D.1040003@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <548E374D.1040003@oracle.com> User-Agent: Mutt/1.5.21 (2010-09-15) X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 14121506-0017-0000-0000-0000071D6E61 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Dec 14, 2014 at 08:20:13PM -0500, Sasha Levin wrote: > On 12/14/2014 07:11 PM, Paul E. McKenney wrote: > >> Does it depend on anything not currently in -next? My build fails with > >> > > >> > kernel/rcu/tree.c: In function ‘rcu_report_qs_rdp’: > >> > kernel/rcu/tree.c:2099:6: error: ‘struct rcu_data’ has no member named ‘gpwrap’ > >> > rdp->gpwrap) { > > Indeed it does. Please see below for a port to current mainline. > > With the patch: > > > [ 620.340045] INFO: rcu_preempt detected stalls on CPUs/tasks: > [ 620.341087] (detected by 22, t=8407 jiffies, g=10452, c=10451, q=3622) > [ 620.342154] All QSes seen, last rcu_preempt kthread activity 4294990929/4294999330, jiffies_till_next_fqs=1 OK, 8401 jiffies since the grace-period kthread ran. This is without the "Run grace-period kthreads at real-time priority" patch? > [ 643.710049] INFO: rcu_preempt detected stalls on CPUs/tasks: > [ 643.710073] INFO: rcu_sched detected stalls on CPUs/tasks: > [ 643.710093] 0: (6 ticks this GP) idle=bd5/140000000000002/0 softirq=12421/12421 fqs=0 last_accelerate: 5283/8643, nonlazy_posted: 643841, .. > [ 643.710110] (detected by 1, t=2102 jiffies, g=-292, c=-293, q=0) But this one is real. > [ 643.710112] Task dump for CPU 0: > [ 643.710129] kworker/0:1 R running task 13016 628 2 0x10080008 > [ 643.710148] Workqueue: events vmstat_update > [ 643.710156] ffffffffb0301dc4 ffff88006be15000 ffff880060ba1c70 0000000000000000 > [ 643.710161] ffff88006be10680 ffff8800633efde8 ffffffffa0461f1b ffff88006a776000 > [ 643.710166] ffff880060ba1cb8 ffff880060ba1c78 ffff880060ba1c80 ffff880060ba1c90 > [ 643.710168] Call Trace: > [ 643.710181] [] ? _raw_spin_unlock_irq+0x64/0x200 > [ 643.710191] [] ? process_one_work+0x5fb/0x1660 > [ 643.710197] [] ? worker_thread+0x5c5/0x1680 > [ 643.710205] [] ? __schedule+0xf6f/0x2fc0 > [ 643.710211] [] ? process_one_work+0x1660/0x1660 > [ 643.710216] [] ? kthread+0x1f2/0x2b0 > [ 643.710221] [] ? kthread_worker_fn+0x6a0/0x6a0 > [ 643.710226] [] ? ret_from_fork+0x7c/0xb0 > [ 643.710233] [] ? kthread_worker_fn+0x6a0/0x6a0 Which in theory should have been addressed by the "Make cond_resched_rcu_qs() apply to normal RCU flavors" patch, given that this is CPU 0, which should be taking scheduling clock interrupts. Well, I guess that theory and practice are only the same in theory. :-/ Will dig into it more. Thanx, Paul > [ 643.711486] > [ 643.711486] (detected by 22, t=2104 jiffies, g=10453, c=10452, q=1570) > [ 643.711486] All QSes seen, last rcu_preempt kthread activity 4294999565/4295001669, jiffies_till_next_fqs=1 > > > Thanks, > Sasha > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/