From mboxrd@z Thu Jan 1 00:00:00 1970 From: Oliver Hartkopp Subject: Re: skbuff panic Date: Sat, 05 Jul 2014 12:40:59 +0200 Message-ID: <53B7D63B.2060108@hartkopp.net> References: Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Return-path: Received: from mo4-p00-ob.smtp.rzone.de ([81.169.146.220]:34889 "EHLO mo4-p00-ob.smtp.rzone.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754044AbaGEKlE (ORCPT ); Sat, 5 Jul 2014 06:41:04 -0400 In-Reply-To: Sender: linux-can-owner@vger.kernel.org List-ID: To: Austin Schuh , linux-can@vger.kernel.org On 04.07.2014 01:03, Austin Schuh wrote: > I'm seeing the following panic. I've seen it on multiple kernel > versions (3.10.24 patched, and 3.14.3). > > uname -a > Linux vpc5 3.14.3-rt4abs+ #16 SMP PREEMPT RT Tue Jul 1 16:28:26 PDT > 2014 x86_64 GNU/Linux > > Jul 3 12:18:28 vpc7 kernel: [ 16.691928] skbuff: skb_under_panic: > text:ffffffff814fb64d len:-65447 put:-65463 head:ffff880407415080 > data:ffff88030742507f tail:0x58 end:0x80 dev:can0 > Jul 3 12:18:28 vpc7 kernel: [ 16.692207] ------------[ cut here ]------------ > Jul 3 12:18:28 vpc7 kernel: [ 16.692209] kernel BUG at net/core/skbuff.c:100! (..) > Jul 3 12:18:28 vpc7 kernel: [ 16.692330] Call Trace: > Jul 3 12:18:28 vpc7 kernel: [ 16.692340] [] > skb_push+0x38/0x39 > Jul 3 12:18:28 vpc7 kernel: [ 16.692348] [] > packet_rcv_spkt+0x98/0xdf > Jul 3 12:18:28 vpc7 kernel: [ 16.692357] [] > __netif_receive_skb_core+0x459/0x4dc > > Any ideas what is causing it? The issue seems to be that the data > pointer is less than the head pointer, from reading the code. It only > happens right at startup. Hi Austin, as you are using the PF_PACKET socket here - where packet_rcv_spkt() is using skb_push() - the things are slightly different to the PF_CAN handling. Are these kernel panics related to the reception of CAN frames - or do they only show up when you send CAN frames (via PF_PACKET socket)?? Can you tell something more about how you send and receive CAN frames in your setup? Best regards, Oliver