linux-kernel - Re: Question on lockdep and MAX_LOCK

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Date:	Wed, 06 Feb 2013 07:56:05 -0800
From:	Ben Greear <greearb@...delatech.com>
To:	Steven Rostedt <rostedt@...dmis.org>
CC:	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...nel.org>
Subject: Re: Question on lockdep and MAX_LOCK_DEPTH

On 02/06/2013 05:21 AM, Steven Rostedt wrote:
> On Tue, 2013-02-05 at 22:23 -0800, Ben Greear wrote:
>> On 02/05/2013 08:36 PM, Steven Rostedt wrote:
>>> On Tue, 2013-02-05 at 19:30 -0800, Ben Greear wrote:
>>>
>>>> It's huge, so here's a link:
>>>>
>>>> http://www.candelatech.com/~greearb/debug.tgz
>>>>
>>>
>>> The trace shows that __netif_receive_skb() is grabbing an
>>> rcu_read_lock() but never releasing it. But I don't see any possible way
>>> that can be true in the code.
>>>
>>> Can you apply the following patch and run the trace again. I'd like to
>>> see if the code is going in the path I expect it is.
>>
>> I'll look at this in detail tomorrow.  I have a few patches in dev.c code, maybe
>> I merged something badly....
>
> I wish you told me that in the beginning. That you modified the core
> code. In that case I would have asked to see your modifications before
> anything else.
>
> I'm 99% sure that the bug is in your modifications.

I'm sorry, I tried to make that clear.

My tree is here, minus a few debugging patches related to this bug:

http://dmz2.candelatech.com/git/gitweb.cgi?p=linux-3.7.dev.y/.git;a=summary

It's rebased on top of 3.7.6.

The wanlink module I'm using is outside the tree.  I recently decided to
release this as GPL, so ignore any conflicting copyright notices to
the contrary in the code:

http://www.candelatech.com/~greearb/wanlink.tgz

The wanlink module is a network impairment tool that acts like a 2-port
bridge.  In my current test case, I'm bridging about 300Mbps of traffic
across two ethernet ports.  It blows up immediately after starting the
emulation.

Thanks,
Ben


-- 
Ben Greear <greearb@...delatech.com>
Candela Technologies Inc  http://www.candelatech.com

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