linux-kernel - Re: [PATCH v2] x86/smpboot: Make logical package management more robust

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Message-ID: <20c3f46a-3514-99cb-30c3-cec6e42211cf@oracle.com>
Date:   Tue, 6 Jun 2017 21:48:37 -0400
From:   Boris Ostrovsky <boris.ostrovsky@...cle.com>
To:     Max Vozeler <max@...terhof.net>,
        Thomas Gleixner <tglx@...utronix.de>
Cc:     LKML <linux-kernel@...r.kernel.org>, x86@...nel.org,
        Peter Zijlstra <peterz@...radead.org>,
        Borislav Petkov <bp@...en8.de>,
        "Charles (Chas) Williams" <ciwillia@...cade.com>,
        "M. Vefa Bicakci" <m.v.b@...box.com>,
        Alok Kataria <akataria@...are.com>,
        xen-devel <xen-devel@...ts.xen.org>,
        Juergen Groß <jgross@...e.com>,
        Thomas Weißschuh <kernel@...ssschuh.net>
Subject: Re: [PATCH v2] x86/smpboot: Make logical package management more
 robust



On 06/06/2017 09:39 AM, Max Vozeler wrote:
> Hi Thomas,
> 
> there is a problem booting recent kernels on some Xen domUs hosted by
> provider JiffyBox.
> 
> The kernel seems to crash just after logging
> [    0.038700] SMP alternatives: switching to SMP code


Do you have the crash splat? Stack trace and such.

In fact, full boot log might be useful.

> 
> We started seeing this with 4.9.2 and bisecting the 4.9 stable kernels
> determined that this commit introduced the problem. Reverting it from 4.9.2
> makes the kernel boot again.
> 
> Older kernels (starting from 3.16 up to and including 4.9.1) were running
> fine in this setup. But recent mainline (tested 4.12-rc3) and 4.9.x both
> fail to boot there.
> 
> Unfortunately we have no detailed information about the hypervisor or
> setup and the provider is not very forthcoming with details. I'm attaching
> dmesg of a successful boot (4.9.2 with this commit reverted).
> 
> It shows a fairly old XEN version:
> 
> [    0.000000] Xen version: 3.1.2-416.el5 (preserve-AD)


This is a 10 year old hypervisor so it's not especially surprising that 
newer kernels don't work. (If anything, I am surprised that you actually 
booted 4.9 at all).

There have been a bunch of problems in this area (topology) on PV guests.


-boris