netdev - Re: crash with bridge and inconsistent handling of NETDEV_TX

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Message-ID: <Pine.LNX.4.64.1004210915220.11040@hs20-bc2-1.build.redhat.com>
Date:	Wed, 21 Apr 2010 09:21:47 -0400 (EDT)
From:	Mikulas Patocka <mpatocka@...hat.com>
To:	David Miller <davem@...emloft.net>
cc:	netdev@...r.kernel.org, kaber@...sh.net
Subject: Re: crash with bridge and inconsistent handling of NETDEV_TX_OK



On Tue, 20 Apr 2010, David Miller wrote:

> 
> I looked more at your crash report.
> 
> You shouldn't even be in this code path for other reasons, namely
> skb->next should be NULL.  But it's not in your case.  skb->next would
> only be non-NULL for GSO frames, which we've established we should not
> be seeing here.
> 
> Given that skb->next is non-NULL and the fraglists of this SKB are
> corrupted (next pointer is 0x18), I think we're getting memory
> corruption from somewhere else.  This also jives with the fact that
> this is not readily reproducable.

The crash happened just a few days after I started to use the machine for 
bridging. There were no unexplained crashes before. So I suspect that the 
cause is bridging or tg3.

> The whole ->ndo_start_xmit() return value stuff is unrelated to this
> issue, we shouldn't even be in this code path.  In fact, if reverting
> that TX flags handling commit makes your crashes go away it would be a
> huge surprise.

I thought that if some weird ->ndo_start_xmit() return values appeared, 
this would lead to misunderstanding who owns the skb, using of already 
deallocated skb and mentioned memory corruption. But I can't prove it.

Mikulas
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