From mboxrd@z Thu Jan 1 00:00:00 1970 Received: with ECARTIS (v1.0.0; list linux-mips); Thu, 17 Mar 2016 03:10:08 +0100 (CET) Received: from forward.webhostbox.net ([5.100.155.97]:60436 "EHLO forward.webhostbox.net" rhost-flags-OK-OK-OK-OK) by eddie.linux-mips.org with ESMTP id S27013913AbcCQCKHAmZEx (ORCPT ); Thu, 17 Mar 2016 03:10:07 +0100 Received: from bh-25.webhostbox.net (bh-25.webhostbox.net [208.91.199.152]) by forward.webhostbox.net (Postfix) with ESMTP id B079A55C0C95; Thu, 17 Mar 2016 02:10:04 +0000 (GMT) Received: from 108-223-40-66.lightspeed.sntcca.sbcglobal.net ([108.223.40.66]:36286 helo=server.roeck-us.net) by bh-25.webhostbox.net with esmtpsa (TLSv1:DHE-RSA-AES128-SHA:128) (Exim 4.86_1) (envelope-from ) id 1agNO1-000a91-JG; Thu, 17 Mar 2016 02:10:06 +0000 Subject: Re: linux-next: Tree for Mar 14 (mips qemu failure bisected) To: Qais Yousef References: <20160314174037.0097df55@canb.auug.org.au> <20160314143729.GA31845@roeck-us.net> <20160315052659.GA9320@roeck-us.net> <56E884BA.5050103@gmail.com> <20160316001713.GA4412@roeck-us.net> <20160316132210.GA21918@roeck-us.net> <56E9C1CA.7050208@gmail.com> <56E9DB85.9090405@gmail.com> Cc: Stephen Rothwell , linux-next@vger.kernel.org, linux-kernel@vger.kernel.org, Ralf Baechle , linux-mips@linux-mips.org From: Guenter Roeck Message-ID: <56EA11FC.9000304@roeck-us.net> Date: Wed, 16 Mar 2016 19:10:04 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.6.0 MIME-Version: 1.0 In-Reply-To: <56E9DB85.9090405@gmail.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit X-Authenticated_sender: linux@roeck-us.net X-OutGoing-Spam-Status: No, score=-1.0 X-CMAE-Score: 0 X-CMAE-Analysis: v=2.1 cv=NfdGrz34 c=1 sm=1 tr=0 a=QNED+QcLUkoL9qulTODnwA==:117 a=2cfIYNtKkjgZNaOwnGXpGw==:17 a=L9H7d07YOLsA:10 a=9cW_t1CCXrUA:10 a=s5jvgZ67dGcA:10 a=IkcTkHD0fZMA:10 a=7OsogOcEt9IA:10 a=l6tbvJ-aNi5sKVHcVUAA:9 a=QEXdDO2ut3YA:10 Return-Path: X-Envelope-To: <"|/home/ecartis/ecartis -s linux-mips"> (uid 0) X-Orcpt: rfc822;linux-mips@linux-mips.org Original-Recipient: rfc822;linux-mips@linux-mips.org X-archive-position: 52611 X-ecartis-version: Ecartis v1.0.0 Sender: linux-mips-bounce@linux-mips.org Errors-to: linux-mips-bounce@linux-mips.org X-original-sender: linux@roeck-us.net Precedence: bulk List-help: List-unsubscribe: List-software: Ecartis version 1.0.0 List-Id: linux-mips X-List-ID: linux-mips List-subscribe: List-owner: List-post: List-archive: X-list: linux-mips On 03/16/2016 03:17 PM, Qais Yousef wrote: > On 16/03/2016 20:27, Qais Yousef wrote: >> >> >> On 16/03/2016 13:22, Guenter Roeck wrote: >>> On Tue, Mar 15, 2016 at 05:17:13PM -0700, Guenter Roeck wrote: >>>> On Tue, Mar 15, 2016 at 09:55:06PM +0000, Qais Yousef wrote: >>>>> Hi Guenter, >>>>> >>> [ ... ] >>>>>>> Qemu test results: >>>>>>> total: 96 pass: 69 fail: 27 >>>>>>> Failed tests: >>>>>> [ ... ] >>>>>>> mips:mips_malta_smp_defconfig >>>>>> I bisected this failure to commit bb11cff327e54 ("MIPS: Make smp CMP, CPS and MT >>>>>> use the new generic IPI functions". Bisect log is attached. >>>>> Thanks for bisecting this. I tested this on a real Malta system but not >>>>> qemu. I'll try to reproduce. >>>>> >>>> I run the tests with only a single CPU core enabled. Maybe that causes >>>> problems with your code ? >>>> >>> I ran another qemu test (this time on mainline) with "-smp 2", but the only >>> difference is that the image now gets stuck even earlier. >>> >>> Also, I ran another set of bisects, this time with both mips and mips64 >>> on mainline (after your patch landed), with the same results. >>> >>> Guenter >>> >> >> OK thanks for the info. The offending commit just enables using quite a few of the newly added code before that. So the problem could be in any of the newly added code. >> >> Unfortunately I can only look at this during my limited time in the evening and I have to setup my system to compile and run this, so I won't be able to get to the bottom of this as fast as I'd like to. >> >> Qais > > OK I was up and running faster than I thought I would be. Can you confirm that you're hitting a BUG_ON() in mips_smp_ipi_init()? > Most likely, but mips is one of the qemu emulations which simply hang if there is a crash, without a log message, and I have not been able to figure out a command line that gives me the actual crash log. > What I see is that BUG_ON() is hit because we couldn't find an ipidomain to allocate the ipis from. The reason of whih is that the qemu malta machine doesn't have a GIC though the config is compiled with GIC on. Also if I remember correctly qemu malta doesn't really support SMP. I think that was the reason I never ran this on qemu. > Idea is to run the SMP build, not really a multi-core machine. > I'm not sure what's the best way forward here. I can add a check to verify gic_present inside this function and return early. Patch attached. > With your patch I get WARNING: CPU: 0 PID: 1 at arch/mips/kernel/smp.c:251 mips_smp_ipi_init+0x3c/0x1b0() and the boot continues. If Ralf accepts it, feel free to add Tested-by: Guenter Roeck though I'll probably adjust my configuration to drop GIC from it (if that is possible). Thanks a lot for looking into this! Guenter