linux-kernel - Re: rcu: INFO: rcu_preempt detected stalls on CPUs/tasks on v3.6

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Message-ID: <50106247.1090502@gmail.com>
Date:	Wed, 25 Jul 2012 23:16:55 +0200
From:	Sasha Levin <levinsasha928@...il.com>
To:	Michael Wang <wangyun@...ux.vnet.ibm.com>
CC:	paulmck@...ux.vnet.ibm.com,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: rcu: INFO: rcu_preempt detected stalls on CPUs/tasks on v3.6

On 07/25/2012 10:36 AM, Michael Wang wrote:
> On 07/25/2012 01:10 AM, Sasha Levin wrote:
>> Hi all,
>>
>> I was fuzzing with trinity inside a KVM tools guest, on the current 3.6, and stumbled on the following:
> 
> Hi, Sasha
> 
> I'm currently trying to reproduce this issue on my machine but keep
> failing, it's really make me think the issue has been solved...

I see this happening on both with -next and current Linus' master.

> Could you please provide more info about you environment? like the
> .config and is there some plugin devices which is rarely.

I've attached the .config. The only device attached to the guest is a virtio-9p device which provides the filesystem, but I don't think it's related to the issue.

> It will be better if you can make your test environment as clean as
> possible (remove the devices which could be remove) and then see whether
> the issue still exist.

I can't remove the filesystem device, other that that nothing else is attached to the guest.

On 07/25/2012 11:06 AM, Michael Wang wrote:
> And is this a host dmesg or from the guest?

guest dmesg, nothing appeared in the host.

> Could you please provide more details about your testing environment?

The guest is running a -next/3.6 kernel built with the attached .config. In that guest I run an instance of the trinity fuzzer.
Nothing else is attached to the guest.
The host is running a 3.5 kernel, and running the guest within KVM tools.

If you need more specific info about anything let me know.

View attachment "config_fuzzkvm" of type "text/plain" (131652 bytes)