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Date: Thu, 08 Mar 2007 14:44:24 -0800 (PST)
Message-Id: <20070308.144424.95895126.davem@davemloft.net>
To: jarkao2@o2.pl
Cc: simon@arlott.org, linux-kernel@vger.kernel.org, sri@us.ibm.com,
       netdev@vger.kernel.org, lksctp-developers@lists.sourceforge.net
Subject: Re: [PATCH][SCTP] Re: lockdep: inconsistent lock state
 ipv6_add_addr/sctp_v6_copy_addrlist (2.6.21-rc1)
From: David Miller <davem@davemloft.net>
In-Reply-To: <20070308074751.GA2085@ff.dom.local>
References: <45E15215.4070600@simon.arlott.org.uk>
	<20070308074751.GA2085@ff.dom.local>
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From: Jarek Poplawski <jarkao2@o2.pl>
Date: Thu, 8 Mar 2007 08:47:51 +0100

> On 25-02-2007 10:08, Simon Arlott wrote:
> > This happens on every boot if more information is needed:
> > 
> > [   37.393715] =================================
> > [   37.393830] [ INFO: inconsistent lock state ]
> > [   37.393881] 2.6.21-rc1-git #146
> > [   37.393929] ---------------------------------
> > [   37.393979] inconsistent {softirq-on-R} -> {in-softirq-W} usage.
> > [   37.394040] hotplug/1072 [HC0[0]:SC1[2]:HE1:SE0] takes:
> > [   37.394092]  (&ndev->lock){-+-?}, at: [<b04a7944>] ipv6_add_addr+0x164/0x1e0
> > [   37.394308] {softirq-on-R} state was registered at:
> > [   37.394359]   [<b013fc42>] __lock_acquire+0x622/0xbb0
> > [   37.394515]   [<b0140652>] lock_acquire+0x62/0x80
> > [   37.394678]   [<b0511c65>] _read_lock+0x35/0x50
> > [   37.394834]   [<b050e200>] sctp_v6_copy_addrlist+0x30/0xc0
> ...
> 
> [SCTP] ipv6: inconsistent lock state ipv6_add_addr/sctp_v6_copy_addrlist
> 
> lockdep found that dev->lock taken from softirq in ipv6_add_addr
> is also taken in sctp_v6_copy_addrlist with softirqs enabled, so
> lockup is possible.
> 
> Noticed-by: Simon Arlott <simon@arlott.org>
> Signed-off-by: Jarek Poplawski <jarkao2@o2.pl>

Patch applied, thanks Jarek.