From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7ABBAC433DB for ; Thu, 14 Jan 2021 12:44:38 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [203.11.71.2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id B67BE221E2 for ; Thu, 14 Jan 2021 12:44:37 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B67BE221E2 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.de Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Received: from bilbo.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 4DGkXg3RhSzDrqP for ; Thu, 14 Jan 2021 23:44:35 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=suse.de (client-ip=195.135.220.15; helo=mx2.suse.de; envelope-from=msuchanek@suse.de; receiver=) Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=suse.de Received: from mx2.suse.de (mx2.suse.de [195.135.220.15]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4DGkRy0mhxzDqv9 for ; Thu, 14 Jan 2021 23:40:29 +1100 (AEDT) X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id D3100B80A; Thu, 14 Jan 2021 12:40:24 +0000 (UTC) Date: Thu, 14 Jan 2021 13:40:23 +0100 From: Michal =?iso-8859-1?Q?Such=E1nek?= To: Nicholas Piggin Subject: Re: KVM on POWER8 host lock up since 10d91611f426 ("powerpc/64s: Reimplement book3s idle code in C") Message-ID: <20210114124023.GL6564@kitsune.suse.cz> References: <20200830201145.GA29521@kitsune.suse.cz> <1598835313.5688ngko4f.astroid@bobo.none> <20200831091523.GC29521@kitsune.suse.cz> <87y2lv1430.fsf@mpe.ellerman.id.au> <1599484062.vgmycu6q5i.astroid@bobo.none> <20201016201410.GH29778@kitsune.suse.cz> <1603066878.gtbyofrzyo.astroid@bobo.none> <1603082970.5545yt7raj.astroid@bobo.none> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <1603082970.5545yt7raj.astroid@bobo.none> User-Agent: Mutt/1.11.3 (2019-02-01) X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: ro@suse.de, linuxppc-dev@lists.ozlabs.org, Hari Bathini Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Mon, Oct 19, 2020 at 02:50:51PM +1000, Nicholas Piggin wrote: > Excerpts from Nicholas Piggin's message of October 19, 2020 11:00 am: > > Excerpts from Michal Suchánek's message of October 17, 2020 6:14 am: > >> On Mon, Sep 07, 2020 at 11:13:47PM +1000, Nicholas Piggin wrote: > >>> Excerpts from Michael Ellerman's message of August 31, 2020 8:50 pm: > >>> > Michal Suchánek writes: > >>> >> On Mon, Aug 31, 2020 at 11:14:18AM +1000, Nicholas Piggin wrote: > >>> >>> Excerpts from Michal Suchánek's message of August 31, 2020 6:11 am: > >>> >>> > Hello, > >>> >>> > > >>> >>> > on POWER8 KVM hosts lock up since commit 10d91611f426 ("powerpc/64s: > >>> >>> > Reimplement book3s idle code in C"). > >>> >>> > > >>> >>> > The symptom is host locking up completely after some hours of KVM > >>> >>> > workload with messages like > >>> >>> > > >>> >>> > 2020-08-30T10:51:31+00:00 obs-power8-01 kernel: KVM: couldn't grab cpu 47 > >>> >>> > 2020-08-30T10:51:31+00:00 obs-power8-01 kernel: KVM: couldn't grab cpu 71 > >>> >>> > 2020-08-30T10:51:31+00:00 obs-power8-01 kernel: KVM: couldn't grab cpu 47 > >>> >>> > 2020-08-30T10:51:31+00:00 obs-power8-01 kernel: KVM: couldn't grab cpu 71 > >>> >>> > 2020-08-30T10:51:31+00:00 obs-power8-01 kernel: KVM: couldn't grab cpu 47 > >>> >>> > > >>> >>> > printed before the host locks up. > >>> >>> > > >>> >>> > The machines run sandboxed builds which is a mixed workload resulting in > >>> >>> > IO/single core/mutiple core load over time and there are periods of no > >>> >>> > activity and no VMS runnig as well. The VMs are shortlived so VM > >>> >>> > setup/terdown is somewhat excercised as well. > >>> >>> > > >>> >>> > POWER9 with the new guest entry fast path does not seem to be affected. > >>> >>> > > >>> >>> > Reverted the patch and the followup idle fixes on top of 5.2.14 and > >>> >>> > re-applied commit a3f3072db6ca ("powerpc/powernv/idle: Restore IAMR > >>> >>> > after idle") which gives same idle code as 5.1.16 and the kernel seems > >>> >>> > stable. > >>> >>> > > >>> >>> > Config is attached. > >>> >>> > > >>> >>> > I cannot easily revert this commit, especially if I want to use the same > >>> >>> > kernel on POWER8 and POWER9 - many of the POWER9 fixes are applicable > >>> >>> > only to the new idle code. > >>> >>> > > >>> >>> > Any idea what can be the problem? > >>> >>> > >>> >>> So hwthread_state is never getting back to to HWTHREAD_IN_IDLE on > >>> >>> those threads. I wonder what they are doing. POWER8 doesn't have a good > >>> >>> NMI IPI and I don't know if it supports pdbg dumping registers from the > >>> >>> BMC unfortunately. > >>> >> > >>> >> It may be possible to set up fadump with a later kernel version that > >>> >> supports it on powernv and dump the whole kernel. > >>> > > >>> > Your firmware won't support it AFAIK. > >>> > > >>> > You could try kdump, but if we have CPUs stuck in KVM then there's a > >>> > good chance it won't work :/ > >>> > >>> I haven't had any luck yet reproducing this still. Testing with sub > >>> cores of various different combinations, etc. I'll keep trying though. > >> > >> Hello, > >> > >> I tried running some KVM guests to simulate the workload and what I get > >> is guests failing to start with a rcu stall. Tried both 5.3 and 5.9 > >> kernel and qemu 4.2.1 and 5.1.0 > >> > >> To start some guests I run > >> > >> for i in $(seq 0 9) ; do /opt/qemu/bin/qemu-system-ppc64 -m 2048 -accel kvm -smp 8 -kernel /boot/vmlinux -initrd /boot/initrd -nodefaults -nographic -serial mon:telnet::444$i,server,wait & done > >> > >> To simulate some workload I run > >> > >> xz -zc9T0 < /dev/zero > /dev/null & > >> while true; do > >> killall -STOP xz; sleep 1; killall -CONT xz; sleep 1; > >> done & > >> > >> on the host and add a job that executes this to the ramdisk. However, most > >> guests never get to the point where the job is executed. > >> > >> Any idea what might be the problem? > > > > I would say try without pv queued spin locks (but if the same thing is > > happening with 5.3 then it must be something else I guess). > > > > I'll try to test a similar setup on a POWER8 here. > > Couldn't reproduce the guest hang, they seem to run fine even with > queued spinlocks. Might have a different .config. > > I might have got a lockup in the host (although different symptoms than > the original report). I'll look into that a bit further. Hello, any progress on this? I considered reinstating the old assembly code for POWER[78] but even the way it's called has changed slightly. Thanks Michal