Message-ID: <4B5C4E5E.2010507@gmail.com>
Date: Sun, 24 Jan 2010 14:42:54 +0100
From: Eric Dumazet <eric.dumazet@gmail.com>
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To: =?ISO-8859-1?Q?Bruno_Pr=E9mont?= <bonbons@linux-vserver.org>
CC: "David S. Miller" <davem@davemloft.net>, netdev@vger.kernel.org,
       linux-kernel@vger.kernel.org
Subject: Re: [2.6.33-rc5 regression] NULL pointer dereference in vlan_skb_recv
 - probably introduced by commit 9793241fe92f7d9303fb221e43fc598eb065f267
References: <20100123165657.187c11e4@neptune.home> <20100123223132.0e62d8cb@neptune.home>
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Le 23/01/2010 22:31, Bruno Pr?mont a ?crit :
>> Above part of code did change between 2.6.32 and 2.6.33-rc5 with
>> commit 9793241fe92f7d9303fb221e43fc598eb065f267 (vlan: Precise RX
>> stats accounting)
>> http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commitdiff;h=9793241fe92f7d9303fb221e43fc598eb065f267
> 
> Reverting just that commit gets the system running correctly.
> 
> Bruno

I have no idea how this patch can break vlan networking.

Your disassembly and .config seems to show your machine is not SMP

Maybe something is broken on UP and alloc_percpu() ?

Could you add a debug in vlan_dev_init()


 	vlan_dev_info(dev)->vlan_rx_stats = alloc_percpu(struct vlan_rx_stats);
	if (!vlan_dev_info(dev)->vlan_rx_stats)
 	return -ENOMEM;
+	pr_err("vlan_dev_init() rx_stats=%p\n", vlan_dev_info(dev)->vlan_rx_stats);


This make sure vlan_dev_init() is called and percpu allocation is properly done.

Thanks
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