Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751753AbbHCWEG (ORCPT ); Mon, 3 Aug 2015 18:04:06 -0400 Received: from e34.co.us.ibm.com ([32.97.110.152]:46007 "EHLO e34.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754319AbbHCWD7 (ORCPT ); Mon, 3 Aug 2015 18:03:59 -0400 X-Helo: d03dlp02.boulder.ibm.com X-MailFrom: paulmck@linux.vnet.ibm.com X-RcptTo: linux-kernel@vger.kernel.org Date: Mon, 3 Aug 2015 15:03:55 -0700 From: "Paul E. McKenney" To: Dave Jones , Linux Kernel , Josh Triplett , sasha.levin@oracle.com, fweisbec@gmail.com Subject: Re: 4.2-rc5 rcu stalls. Message-ID: <20150803220355.GO27280@linux.vnet.ibm.com> Reply-To: paulmck@linux.vnet.ibm.com References: <20150803210835.GA4467@codemonkey.org.uk> <20150803213723.GN27280@linux.vnet.ibm.com> <20150803215535.GA13717@codemonkey.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20150803215535.GA13717@codemonkey.org.uk> User-Agent: Mutt/1.5.21 (2010-09-15) X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 15080322-0017-0000-0000-00000CD18BA1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2833 Lines: 54 On Mon, Aug 03, 2015 at 05:55:35PM -0400, Dave Jones wrote: > Content analysis details: (-2.9 points, 5.0 required) > > pts rule name description > ---- ---------------------- -------------------------------------------------- > -1.0 ALL_TRUSTED Passed through trusted hosts only via SMTP > -1.9 BAYES_00 BODY: Bayes spam probability is 0 to 1% > [score: 0.0000] > X-Authenticated-User: davej@codemonkey.org.uk > X-ZLA-Header: unknown; 0 > X-ZLA-DetailInfo: BA=6.00003574; NDR=6.00000001; ZLA=6.00000002; ZF=6.00000004; ZB=6.00041153; ZH=6.00102541; ZP=6.00079473; ZU=6.00000001; UDB=6.00244665; UTC=2015-08-03 21:55:44 > x-cbid: 15080321-0049-0000-0000-0000023893EC > X-IBM-ISS-SpamDetectors: Score=0.399202; BY=0; FL=0; FP=0; FZ=0; HX=0; KW=0; > PH=0; RB=0; SC=0.399202; ST=0; TS=0; UL=0; ISC= > X-IBM-ISS-DetailInfo: BY=3.00004248; HX=3.00000236; KW=3.00000007; > PH=3.00000003; SC=3.00000115; SDB=6.00568916; UDB=6.00244665; UTC=2015-08-03 > 21:55:45 > X-TM-AS-MML: disable > > On Mon, Aug 03, 2015 at 02:37:23PM -0700, Paul E. McKenney wrote: > > On Mon, Aug 03, 2015 at 05:08:35PM -0400, Dave Jones wrote: > > > [ 2120.855128] Tasks blocked on level-0 rcu_node (CPUs 0-3): P1497 > > > [ 2120.855263] (detected by 2, t=65002 jiffies, g=78835, c=78834, q=0) > > > [ 2120.855403] trinity-watchdo R running task 14336 1497 1496 0x00080000 > > > [ 2120.855563] ffff8804b94e3c88 ffffffffa17fa0b0 ffff8805010a1b40 ffff8804f58b51c0 > > > [ 2120.855728] ffff8805010a1b40 ffff8804b94e3c78 0000000000000000 ffff8804b94e4000 > > > [ 2120.855893] 0000000000000001 0000000000000001 0000000000000002 ffff8804b94e3ca8 > > > [ 2120.856062] Call Trace: > > > [ 2120.856116] [] ? preempt_schedule_irq+0x40/0xa0 > > > [ 2120.856252] [] preempt_schedule_irq+0x46/0xa0 > > > > Sasha Levin (CCed) was having roughly similar stalls, and found that > > reverting b30f0e3ffedf (sched/preempt: Optimize preemption operations > > on __schedule() callers) made the stalls go away. Does that help in > > your case? > > Ugh, that doesn't revert cleanly. Got something handy ? I do not, but perhaps either Sasha or Frederic do. > The curious thing is why I've only just started seeing these. > I've had that machine for a month now, so it's been fuzzing since ~4.1, > and until yesterday I'd not seen this at all. It could well be a new problem. I just saw the preempt_schedule_irq() and was reminded of the problem that Sasha found. ;-) Thanx, Paul -- 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/