From mboxrd@z Thu Jan 1 00:00:00 1970 From: Vlad Yasevich Subject: Re: WARNING: at net/core/skbuff.c:154 with tcpdump and ipsec Date: Fri, 13 Feb 2009 14:42:07 -0500 Message-ID: <4995CD0F.8020307@hp.com> References: <20090213121424.GA8717@ff.dom.local> <4995C241.1030507@hp.com> <20090213192448.GA2929@ami.dom.local> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: Krzysztof Oledzki , Marco Berizzi , netdev@vger.kernel.org To: Jarek Poplawski Return-path: Received: from g5t0009.atlanta.hp.com ([15.192.0.46]:39251 "EHLO g5t0009.atlanta.hp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750797AbZBMTmJ (ORCPT ); Fri, 13 Feb 2009 14:42:09 -0500 In-Reply-To: <20090213192448.GA2929@ami.dom.local> Sender: netdev-owner@vger.kernel.org List-ID: Jarek Poplawski wrote: > On Fri, Feb 13, 2009 at 01:56:01PM -0500, Vlad Yasevich wrote: > ... >> I did notice that pskb_expand_head() doesn't change the skb->truesize even >> though it could grow the skb. I saw this problem with tcpdump while >> experimenting with some SCTP code. >> >> This is not to say that it is the problem in this case, but it's one of >> them that I've seen. > > Yes, I've read Herbert Xu's message pointing especially to > xfrm_state_check_space(). So I would like to make sure if there is no > other reason it triggers in packet_recvmsg() on these several reports. > > If af_packet code is OK, I guess we could update truesize for it: > there is no reason to warn here about bugs from other, well known > places. > Personally, I think pskb_expand_head should fix the skb->truesize. This way any subsequent clones will not trigger this warning. Another alternative is to audit the pskb_expand_head() usages and adjust truesize in each case needed, which is just ugly. -vlad > Jarek P. >