From: Andi Kleen <andi@firstfloor.org>
To: Igor Mammedov <imammedo@redhat.com>
Cc: Andi Kleen <andi@firstfloor.org>,
linux-kernel@vger.kernel.org, tglx@linutronix.de,
mingo@redhat.com, hpa@zytor.com, x86@kernel.org, bp@suse.de,
paul.gortmaker@windriver.com, JBeulich@suse.com,
prarit@redhat.com, drjones@redhat.com, toshi.kani@hp.com,
riel@redhat.com, gong.chen@linux.intel.com
Subject: Re: [PATCH v2 1/5] x86: replace timeouts when booting secondary CPU with infinite wait loop
Date: Thu, 3 Apr 2014 01:48:10 +0200 [thread overview]
Message-ID: <20140402234810.GO22728@two.firstfloor.org> (raw)
In-Reply-To: <20140402232956.54848fbe@thinkpad>
On Wed, Apr 02, 2014 at 11:29:56PM +0200, Igor Mammedov wrote:
> On Wed, 02 Apr 2014 10:15:29 -0700
> Andi Kleen <andi@firstfloor.org> wrote:
>
> > Igor Mammedov <imammedo@redhat.com> writes:
> >
> > > Hang is observed on virtual machines during CPU hotplug,
> > > especially in big guests with many CPUs. (It reproducible
> > > more often if host is over-committed).
> > >
> > > It happens because master CPU gives up waiting on
> > > secondary CPU and allows it to run wild. As result
> > > AP causes locking or crashing system. For example
> > > as described here: https://lkml.org/lkml/2014/3/6/257
> > >
> > > If master CPU have sent STARTUP IPI successfully,
> > > make it wait indefinitely till AP boots.
> >
> >
> > But what happens on a real machine when the other CPU is dead?
> One possible way to boot such machine would be to disable dead CPU
> in kernel parameters.
That would need explicit user action. It's much better to recover
automatically, even if somewhat crippled.
-Andi
next prev parent reply other threads:[~2014-04-02 23:48 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-03-31 20:09 [PATCH v2 0/5] x86: fix hang when AP bringup is too slow Igor Mammedov
2014-03-31 20:09 ` [PATCH v2 1/5] x86: replace timeouts when booting secondary CPU with infinite wait loop Igor Mammedov
2014-04-02 17:15 ` Andi Kleen
2014-04-02 21:29 ` Igor Mammedov
2014-04-02 23:48 ` Andi Kleen [this message]
2014-04-03 6:43 ` Ingo Molnar
2014-04-03 21:03 ` Andi Kleen
2014-03-31 20:09 ` [PATCH v2 2/5] x86: cleanup not needed cpu_initialized_mask Igor Mammedov
2014-03-31 20:09 ` [PATCH v2 3/5] x86: log error on secondary CPU wakeup failure at ERR level Igor Mammedov
2014-03-31 20:09 ` [PATCH v2 4/5] x86: fix list corruption on CPU hotplug Igor Mammedov
2014-03-31 20:09 ` [PATCH v2 5/5] x86: fix memory corruption in acpi_unmap_lsapic() Igor Mammedov
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