From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
        id S1753889AbdIDQcQ convert rfc822-to-8bit (ORCPT <rfc822;w@1wt.eu>);
        Mon, 4 Sep 2017 12:32:16 -0400
Received: from mout.gmx.net ([212.227.17.21]:58390 "EHLO mout.gmx.net"
        rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP
        id S1752687AbdIDQcP (ORCPT <rfc822;linux-kernel@vger.kernel.org>);
        Mon, 4 Sep 2017 12:32:15 -0400
Message-ID: <1504542701.22981.3.camel@gmx.de>
Subject: Re: hotplug lockdep splat (tip)
From: Mike Galbraith <efault@gmx.de>
To: Peter Zijlstra <peterz@infradead.org>
Cc: LKML <linux-kernel@vger.kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Byungchul Park <max.byungchul.park@gmail.com>
Date: Mon, 04 Sep 2017 18:31:41 +0200
In-Reply-To: <20170904142419.6dfbwx5eedkykpeo@hirez.programming.kicks-ass.net>
References: <1504350596.16793.44.camel@gmx.de>
         <1504421975.30792.32.camel@gmx.de>
         <20170904075502.74pgfd2twdfklspw@hirez.programming.kicks-ass.net>
         <1504531627.10288.5.camel@gmx.de>
         <20170904142419.6dfbwx5eedkykpeo@hirez.programming.kicks-ass.net>
Content-Type: text/plain; charset="UTF-8"
X-Mailer: Evolution 3.20.5 
Mime-Version: 1.0
Content-Transfer-Encoding: 8BIT
X-Provags-ID: V03:K0:FCgGo5SW8EfmRluavUljmVJY8+1HkX0sE8tyV6hC/Vi4J8WKgSC
 Qy8UbB00dlkVYZ8jSXwbO50Jq9i2L+csmniNCGFqhj6mtV0rkf4LRHtAOpE7fFXAKg3/ClA
 5b4IlhnlGVqAXv7tL4bRNqSyp9PEU2jytciV6DV/qCSkuMflegnQ+O4+QYT40eDzdweC7bu
 erI4RXUnQAAU0zZ6RTRHQ==
X-UI-Out-Filterresults: notjunk:1;V01:K0:lOAmO8WCOyU=:yzjDSMEugBdM67MVY25fwO
 XDmrsytK4PxQAto8HjFVvSmTOm93mQ/ILKj2M62QwmPbFsqif+9YBwnlTua5xA00u8fwAAurD
 DU1aYVtEg5hBa+rmnuNE0bpurtzx+ZP/jTY9ndTq02vdG3smvgFf+n44wib2fU0LlKwKLutKa
 gcXj9KXnW5/4xar19TMODZJup8nUiZ/VNHpM/kZWAB2H8RB50SqP5ypaMT2FgkfGw9P4JCL7M
 S4KcGlk04qWH9xdQLZsY0aTsfxgizityALVgUVRwBtLUnMh/fWDmgRrc0OrNmwDuRnRhGt88P
 8mU6rEMi7IllJBwBuaSlcjfF3+4qFW3dp/QgOAbhAP31WFz9bm7VwTV2Ip3iASFO/GNUBjqpc
 xtKdNNwW/5APrWy7jUEf+tJYpX+7TvSTCD8VZ3qgv5zwrwu3tVWf3U6zS3nUtDvHfKjtl3rS4
 P3Myel+rQrLuhaAyD8HqSVG+0jx/fcu/jRCjQdf7RruA8RVMqCvrW8g62shFhOeAN5KW6cOXD
 E01cExwDLVTDF6w1lT8Ys/oDA9OuXofczg6d6SdNtKsPshvg1CrIVctiWJBJAHOLwgQLeltCc
 1GnwxaF+2p9sLx/8x98btFA+AkGNqPKthNzUbxrojLkm45ubJZiC36tnp2quT2Vm2q2NkyfXa
 D+IQjzN4OPagqq8JY08JsF6FjLejKkXX/NgWuuzh86/rCB8X1tW6irMn3F8m7jDaUBQ6WlIVh
 NM2Lhpa3meu8OCUmpxwtWhPltYCWRSx5l7ZRATbYyn08q7k0YjTp1/6uL7CthTeqgbuBSOwKr
 GGsIolVf2qhJJoTkgBwzGNoSHb3nHQBBBR4JGkSwBW7NICcsDs=
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On Mon, 2017-09-04 at 16:24 +0200, Peter Zijlstra wrote:
> On Mon, Sep 04, 2017 at 03:27:07PM +0200, Mike Galbraith wrote:
> > On Mon, 2017-09-04 at 09:55 +0200, Peter Zijlstra wrote:
> > > On Sun, Sep 03, 2017 at 08:59:35AM +0200, Mike Galbraith wrote:
> > > > 
> > > > [  126.626908] Unregister pv shared memory for cpu 1
> > > > [  126.631041] 
> > > > [  126.631269] ======================================================
> > > > [  126.632442] WARNING: possible circular locking dependency detected
> > > > [  126.633599] 4.13.0.g06260ca-tip-lockdep #2 Tainted: G            E  
> > > > [  126.634380] ------------------------------------------------------
> > > > [  126.635124] stress-cpu-hotp/3156 is trying to acquire lock:
> > > > [  126.635804]  ((complete)&st->done){+.+.}, at: [<ffffffff8108d19a>] takedown_cpu+0x8a/0xf0
> > > > [  126.636809] 
> > > > [  126.636809] but task is already holding lock:
> > > > [  126.637567]  (sparse_irq_lock){+.+.}, at: [<ffffffff81107ac7>] irq_lock_sparse+0x17/0x20
> > > > [  126.638665] 
> > > 
> > > https://lkml.kernel.org/r/20170829193416.GC32112@worktop.programming.kicks-ass.net
> > 
> > Well, flavor of gripe changed.
> > 
> > [  164.114290] ======================================================
> > [  164.115146] WARNING: possible circular locking dependency detected
> > [  164.115751] 4.13.0.g90abd70-tip-lockdep #4 Tainted: G            E  
> > [  164.116348] ------------------------------------------------------
> > [  164.116919] cpuhp/0/12 is trying to acquire lock:
> > [  164.117381]  (cpuhp_state){+.+.}, at: [<ffffffff8108e4aa>] cpuhp_thread_fun+0x2a/0x160
> > [  164.118097] 
> >                but now in release context of a crosslock acquired at the following:
> > [  164.118845]  ((complete)&per_cpu_ptr(&cpuhp_state, i)->done#2){+.+.}, at: [<ffffffff8108e71f>] cpuhp_issue_call+0x13f/0x170
> > [  164.119789] 
> 
> Cute, I'd not seen that one.. anything special required to reproduce?

No.  I build an enterprise(ish) config, run it in a KVM box, with the
guest being a full clone of the host, just memory constrained so it
can't oom the host.

	-Mike