From owner-freebsd-net@freebsd.org Wed Sep 5 08:44:34 2018 Return-Path: Delivered-To: freebsd-net@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 5313BFE8D50 for ; Wed, 5 Sep 2018 08:44:34 +0000 (UTC) (envelope-from zec@fer.hr) Received: from mailman.ysv.freebsd.org (mailman.ysv.freebsd.org [IPv6:2001:1900:2254:206a::50:5]) by mx1.freebsd.org (Postfix) with ESMTP id EAA9777D4F for ; Wed, 5 Sep 2018 08:44:33 +0000 (UTC) (envelope-from zec@fer.hr) Received: by mailman.ysv.freebsd.org (Postfix) id AC36BFE8D4E; Wed, 5 Sep 2018 08:44:33 +0000 (UTC) Delivered-To: net@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 9B078FE8D4D for ; Wed, 5 Sep 2018 08:44:33 +0000 (UTC) (envelope-from zec@fer.hr) Received: from mail.fer.hr (mail.fer.hr [161.53.72.233]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-SHA384 (256/256 bits)) (Client CN "mail.fer.hr", Issuer "TERENA SSL CA 3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 2015477D4C; Wed, 5 Sep 2018 08:44:32 +0000 (UTC) (envelope-from zec@fer.hr) Received: from x23 (161.53.19.9) by MAIL.fer.hr (161.53.72.233) with Microsoft SMTP Server (TLS) id 14.3.399.0; Wed, 5 Sep 2018 10:44:30 +0200 Date: Wed, 5 Sep 2018 10:44:33 +0200 From: Marko Zec To: Vincenzo Maffione CC: Luigi Rizzo , "freebsd-net@freebsd.org" , "Bjoern A. Zeeb" Subject: Re: vale and netmap module questions Message-ID: <20180905104433.08ad13b8@x23> In-Reply-To: References: <20180901014953.GV45503@funkthat.com> <20180901211123.GZ45503@funkthat.com> <20180904164303.68c43b6e@x23> <20180904162815.GA75530@funkthat.com> X-Mailer: Claws Mail 3.16.0 (GTK+ 2.24.32; amd64-portbld-freebsd11.1) MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit X-Originating-IP: [161.53.19.9] X-BeenThere: freebsd-net@freebsd.org X-Mailman-Version: 2.1.27 Precedence: list List-Id: Networking and TCP/IP with FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 05 Sep 2018 08:44:34 -0000 On Tue, 4 Sep 2018 20:18:29 +0200 Vincenzo Maffione wrote: > Hi, > I don't think the panic depends on the architecture. Also, it does > not depend on using emulated mode or not. > We have seen this happening on x86_64 on FreeBSD 12 head. > > As John-Mark says, kdloading netmap.ko is not enough. You need to > open a netmap port corresponding > to any network interface, e.g. > # pkt-gen -i eth0 > because this will trigger ifunit_ref() in the kernel (netmap tries to > grab the interface called "eth0"). > The ifunit_ref() panics and we still need to figure out why. After more carefully rereading jmg's original report, on amd64 I reproduced exactly the same panic he reported on arm64, the summary follows: - the problem can be observed as VNET related, and can be triggered only on kernels built with "options VIMAGE" but without "device netmap". - netmap.ko built using make buildkernel works fine. - netmap.ko built separately (cd sys/modules/netmap; make) panics on a first reference to vale interface, such as "tcpdump -ni vale1:a" - the problem is that the separately built module is compiled without "options VIMAGE", and as such does not set curvnet prior to calling into network stack functions, therefore we have a null pointer dereference in ifunit_ref() and voila... - hence, there's nothing to fix in the netmap code, and there's nothing to fix in the network stack either related to this particular problem, but rather we need a general mechanism which would prevent kldloading non-VNETized .ko modules into a VNETized kernel. I have no idea how to approach this, besides adding bz@ to the cc: list, perhaps he could chime in with some thoughts? Cheers, Marko