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Date: Thu, 05 Aug 2010 09:57:14 -0700
From: Ben Greear <greearb@candelatech.com>
Organization: Candela Technologies
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To: "Eric W. Biederman" <ebiederm@xmission.com>
CC: Michael Leun <lkml20100708@newton.leun.net>, Greg KH <greg@kroah.com>,
        netdev@vger.kernel.org, davem@davemloft.net,
        linux-kernel@vger.kernel.org, Alexey Dobriyan <adobriyan@gmail.com>,
        Patrick McHardy <kaber@trash.net>
Subject: Re: NET_NS: unregister_netdevice: waiting for lo to become free (after
 using openvpn)
References: <loom.20100708T183152-326@post.gmane.org>	<20100709235744.GA12752@kroah.com>	<20100710101540.2799c9ef@xenia.leun.net>	<20100710140800.GA20424@kroah.com>	<20100710165208.59272ae6@xenia.leun.net>	<20100710235323.5336f627@xenia.leun.net>	<20100711192939.1c25dcaf@xenia.leun.net>	<20100804153543.56f6ecad@xenia.leun.net>	<20100804214618.GA6289@kroah.com>	<20100805001105.5a3453ed@xenia.leun.net>	<m1lj8l29zm.fsf@fess.ebiederm.org>	<20100805112538.60a46cb1@xenia.leun.net> <m1y6clz8ta.fsf_-_@fess.ebiederm.org>
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On 08/05/2010 02:51 AM, Eric W. Biederman wrote:
> Michael Leun<lkml20100708@newton.leun.net>  writes:

>> Unfortunately looks like indefinitely. Never watched longer so far
>> (rebooted soon), but I'm seeing this message now repeated every 10 secs
>> for ~10 minutes on a idle system.
>
> Ugh.  A real bug then.  These can be a pain to track down and fix. I
> think the last one of these I tracked down took a couple of weeks.  I
> will start digging in when I get back from vacation.

I once spent a similar amount of time putting in debug variants that
printed info for each time a netdev was acquired and released.

Maybe a similar logic could be put into the official kernel (and
disabled by default)?

That should save effort in the long run, I'd think.

Thanks,
Ben


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