From: Jim Baxter <jim_baxter@mentor.com>
Subject: Re: skbuff truesize incorrect.
Date: Fri, 23 May 2014 12:13:23 +0100
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Cc: 'Eric Dumazet' <eric.dumazet@gmail.com>,
	"linux-usb@vger.kernel.org" <linux-usb@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
	"David S. Miller" <davem@davemloft.net>,
	"kamal@canonical.com" <kamal@canonical.com>,
	"edumazet@google.com" <edumazet@google.com>,
	"mszeredi@suse.cz" <mszeredi@suse.cz>,
	"fw@strlen.de" <fw@strlen.de>
To: David Laight <David.Laight@ACULAB.COM>,
	=?UTF-8?B?J0Jqw7hybiBNb3JrJw==?= <bjorn@mork.no>
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On 23/05/14 11:45, David Laight wrote:
> From: Bj=C3=B8rn Mork [mailto:bjorn@mork.no]
>> David Laight <David.Laight@ACULAB.COM> writes:
> ...
>>> Note that some of the usb ethernet drivers allocate large skb then
>>> lie about the truesize.
>>
>> Hmm, which drivers are these?
>=20
> $ grep truesize linux/drivers/net/usb/*
>=20
> asix_88179_178a, smsc95xx, sr9700.
>=20
> 	David
>=20


What are the side effects of changing the truesize, if the original
uncloned skb has the full truesize then isn't the potential memory usag=
e
still counted for the avoidance of OOM?

I suppose if the uncloned skb is deleted you would then have a problem
so a chain of URB's would be the safest solution.

Jim