From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from e31.co.us.ibm.com (e31.co.us.ibm.com [32.97.110.149]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 0A1A31A0CEC for ; Fri, 16 Jan 2015 20:10:18 +1100 (AEDT) Received: from /spool/local by e31.co.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Fri, 16 Jan 2015 02:10:17 -0700 Received: from b03cxnp07029.gho.boulder.ibm.com (b03cxnp07029.gho.boulder.ibm.com [9.17.130.16]) by d03dlp03.boulder.ibm.com (Postfix) with ESMTP id E2E6A19D803E for ; Fri, 16 Jan 2015 02:01:26 -0700 (MST) Received: from d03av02.boulder.ibm.com (d03av02.boulder.ibm.com [9.17.195.168]) by b03cxnp07029.gho.boulder.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id t0G9AFIp51445764 for ; Fri, 16 Jan 2015 02:10:15 -0700 Received: from d03av02.boulder.ibm.com (localhost [127.0.0.1]) by d03av02.boulder.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id t0G9AEcM000834 for ; Fri, 16 Jan 2015 02:10:14 -0700 Message-ID: <54B8D56D.3070904@linux.vnet.ibm.com> Date: Fri, 16 Jan 2015 14:40:05 +0530 From: Preeti U Murthy MIME-Version: 1.0 To: Michael Ellerman , Alexey Kardashevskiy Subject: Re: offlining cpus breakage References: <54ACFE6D.3070308@ozlabs.ru> <54B7BEF9.8090603@linux.vnet.ibm.com> <54B85B3C.1030000@ozlabs.ru> <1421377482.18166.5.camel@ellerman.id.au> <54B8D228.4000407@linux.vnet.ibm.com> In-Reply-To: <54B8D228.4000407@linux.vnet.ibm.com> Content-Type: text/plain; charset=UTF-8 Cc: "Shreyas B. Prabhu" , "linuxppc-dev@lists.ozlabs.org" , Anton Blanchard , Paul Mackerras List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On 01/16/2015 02:26 PM, Preeti U Murthy wrote: > On 01/16/2015 08:34 AM, Michael Ellerman wrote: >> On Fri, 2015-01-16 at 13:28 +1300, Alexey Kardashevskiy wrote: >>> On 01/16/2015 02:22 AM, Preeti U Murthy wrote: >>>> Hi Alexey, >>>> >>>> Can you let me know if the following patch fixes the issue for you ? >>>> It did for us on one of our machines that we were investigating on. >>> >>> This fixes the issue for me as well, thanks! >>> >>> Tested-by: Alexey Kardashevskiy >> >> OK, that's great. >> >> But, I really don't think we can ask upstream to merge this patch to generic >> code when we don't have a good explanation for why it's necessary. At least I'm >> not going to ask anyone to do that :) >> >> So Pretti can you either write a 100% convincing explanation of why this patch >> is correct in the general case, or (preferably) do some more investigating to >> work out what Alexey's bug actually is. > > Yes will do so. Its better to investigate where precisely is the bug. > This patch helped me narrow down on the buggy scenario. On a side note, while I was tracking the race condition, I noticed that in the final stage of the cpu offline path, after the state of the hotplugged cpu is set to CPU_DEAD, we check if there were interrupts delivered during the soft disabled state and service them if there were. It makes sense to check for pending interrupts in the idle path. In the offline path however, this did not look right to me at first glance. Am I missing something ? Regards Preeti U Murthy > > Regards > Preeti U Murthy >> >> cheers >> >> >> _______________________________________________ >> Linuxppc-dev mailing list >> Linuxppc-dev@lists.ozlabs.org >> https://lists.ozlabs.org/listinfo/linuxppc-dev >> > > _______________________________________________ > Linuxppc-dev mailing list > Linuxppc-dev@lists.ozlabs.org > https://lists.ozlabs.org/listinfo/linuxppc-dev >