From: Toshi Kani <toshi.kani@hp.com>
To: Igor Mammedov <imammedo@redhat.com>
Cc: 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, riel@redhat.com,
gong.chen@linux.intel.com, andi@firstfloor.org, lenb@kernel.org,
rjw@rjwysocki.net, linux-acpi@vger.kernel.org
Subject: Re: [PATCH v5 4/4] x86: initialize secondary CPU only if master CPU will wait for it
Date: Mon, 05 May 2014 15:35:10 -0600 [thread overview]
Message-ID: <1399325710.1789.95.camel@misato.fc.hp.com> (raw)
In-Reply-To: <1399322991-19329-5-git-send-email-imammedo@redhat.com>
On Mon, 2014-05-05 at 22:49 +0200, Igor Mammedov wrote:
> 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,
> and AP signalled to master CPU that it's ready
> to start initialization, make master CPU wait
> indefinitely till AP is onlined.
> To ensure that AP won't ever run wild, make it
> wait at early startup till master CPU confirms its
> intention to wait for AP. If AP doesn't respond in 10
> seconds, the master CPU will timeout and cancel
> AP onlining.
>
> Signed-off-by: Igor Mammedov <imammedo@redhat.com>
Thanks for the update.
Acked-by: Toshi Kani <toshi.kani@hp.com>
-Toshi
next prev parent reply other threads:[~2014-05-05 21:35 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-05-05 20:49 [PATCH v5 0/4] x86: fix hang when AP bringup is too slow Igor Mammedov
2014-05-05 20:49 ` [PATCH v5 1/4] x86: fix list/memory corruption on CPU hotplug Igor Mammedov
2014-05-05 20:49 ` [PATCH v5 2/4] acpi_processor: do not mark present at boot but not onlined CPU as onlined Igor Mammedov
2014-05-07 23:48 ` Rafael J. Wysocki
2014-05-08 6:09 ` Ingo Molnar
2014-05-08 11:33 ` Rafael J. Wysocki
2014-05-08 11:17 ` Ingo Molnar
2014-05-05 20:49 ` [PATCH v5 3/4] x86: log error on secondary CPU wakeup failure at ERR level Igor Mammedov
2014-05-05 20:49 ` [PATCH v5 4/4] x86: initialize secondary CPU only if master CPU will wait for it Igor Mammedov
2014-05-05 21:35 ` Toshi Kani [this message]
2014-06-04 13:21 ` [PATCH v5 0/4] x86: fix hang when AP bringup is too slow Igor Mammedov
2014-06-05 12:29 ` Ingo Molnar
2014-06-05 13:12 ` Igor Mammedov
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