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Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Fri, 21 Dec 2018 06:45:40 -0000 Received: from d06av24.portsmouth.uk.ibm.com (mk.ibm.com [9.149.105.60]) by b06cxnps4074.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id wBL6jdWM65273944 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL); Fri, 21 Dec 2018 06:45:39 GMT Received: from d06av24.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 74FAF42045; Fri, 21 Dec 2018 06:45:39 +0000 (GMT) Received: from d06av24.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 5F36D42049; Fri, 21 Dec 2018 06:45:38 +0000 (GMT) Received: from oc7455500831.ibm.com (unknown [9.145.24.239]) by d06av24.portsmouth.uk.ibm.com (Postfix) with ESMTP; Fri, 21 Dec 2018 06:45:38 +0000 (GMT) Subject: Re: 4.20-rc6: WARNING: CPU: 30 PID: 197360 at net/core/flow_dissector.c:764 __skb_flow_dissect To: Willem de Bruijn , Ido Schimmel Cc: Willem de Bruijn , Michael S Tsirkin , Network Development , "linux-kernel@vger.kernel.org" , "virtualization@lists.linux-foundation.org" References: <20181220091207.GA25942@splinter> <0c5a8fa8-efb3-71f2-0da9-6fc0f133cdf9@de.ibm.com> <20181220141752.GB861@splinter> From: Christian Borntraeger Openpgp: preference=signencrypt Autocrypt: addr=borntraeger@de.ibm.com; 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Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 In-Reply-To: Content-Language: en-US X-TM-AS-GCONF: 00 x-cbid: 18122106-0012-0000-0000-000002DC2410 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 18122106-0013-0000-0000-00002111C86F Message-Id: Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8BIT MIME-Version: 1.0 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2018-12-21_03:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=716 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1812210053 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 20.12.2018 18:23, Willem de Bruijn wrote: > On Thu, Dec 20, 2018 at 11:17 AM Ido Schimmel wrote: >> >> On Thu, Dec 20, 2018 at 03:09:22PM +0100, Christian Borntraeger wrote: >>> On 20.12.2018 10:12, Ido Schimmel wrote: >>>> +Willem >>>> >>>> On Thu, Dec 20, 2018 at 08:45:40AM +0100, Christian Borntraeger wrote: >>>>> Folks, >>>>> >>>>> I got this warning today. I cant tell when and why this happened, so I do not know yet how to reproduce. >>>>> Maybe someone has a quick idea. >>>>> >>>>> [85109.572032] WARNING: CPU: 30 PID: 197360 at net/core/flow_dissector.c:764 __skb_flow_dissect+0x1f0/0x1318 >>>> >>>> I managed to trigger this warning as well the other day, but from a >>>> different call path: >>> >>> FWIW, it also seems to happen on 4.20-rc1. 4.19.0 seems fine. bisect seem to have failed so >>> my reproducer is not reliable. >> >> Yes, it is caused by commit d0e13a1488ad ("flow_dissector: lookup netns >> by skb->sk if skb->dev is NULL") >> >> $ git tag --contains d0e13a1488ad >> v4.20-rc1 >> v4.20-rc2 >> v4.20-rc3 >> v4.20-rc4 >> v4.20-rc5 >> v4.20-rc6 > > That tap_get_user_xdp path is also new for 4.20-rc1: > > commit 0efac27791ee068075d80f07c55a229b1335ce12 > tap: accept an array of XDP buffs through sendmsg() > > $ git describe --contains 0efac27791ee > v4.20-rc1~14^2~382^2~1 > > In v4.19 and before all packets went through tap_get_user. Hmmm, so maybe my bisect wasnt broken at all? It pointed to commit 105bc1306e9b29c2aa2783b9524f7aec9b5a5b1f Merge: 3475372ff60e4 d0e13a1488ad3 Author: David S. Miller AuthorDate: Tue Sep 25 20:29:38 2018 -0700 Commit: David S. Miller CommitDate: Tue Sep 25 20:29:38 2018 -0700 Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next