Return-path: Received: from igw3.br.ibm.com ([32.104.18.26]:51155 "EHLO igw3.br.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752741AbYGWNlw (ORCPT ); Wed, 23 Jul 2008 09:41:52 -0400 Message-ID: <48873502.1030106@linux.vnet.ibm.com> (sfid-20080723_154156_937455_0E404DDA) Date: Wed, 23 Jul 2008 10:41:22 -0300 From: Breno Leitao MIME-Version: 1.0 To: Jiri Slaby CC: "David S. Miller" , netdev , Johannes Berg , Michael Wu , linux-wireless Subject: Re: q == &noop_qdisc warning from 802.11 code References: <488723FF.8070707@gmail.com> In-Reply-To: <488723FF.8070707@gmail.com> Content-Type: text/plain; charset=UTF-8 Sender: linux-wireless-owner@vger.kernel.org List-ID: Jiri Slaby wrote: > Hi, > > I hit the warning from __netif_schedule: I also hit a bug related to noop_qdisc running the net-next kernel. I hit this bug every time I run "ifconfig eth0 mtu 9000; ifconfg eth0 1500" for any interface (tested against s2io and e1000) that is up, otherwise the bug isn't reproducible. The bug dumps the following calltrace: [root@io-dolphins net-next-2.6]# ifconfig eth0 mtu 9000; ifconfig eth0 mtu 1500 ------------[ cut here ]------------ kernel BUG at net/core/dev.c:1328! cpu 0x1: Vector: 700 (Program Check) at [c0000000be3d3460] pc: c0000000003603ac: .__netif_schedule+0x2c/0xb8 lr: d00000000026b014: .s2io_change_mtu+0x1c4/0x27c [s2io] sp: c0000000be3d36e0 msr: 8000000000029032 current = 0xc0000000bc4042b0 paca = 0xc0000000006f3680 pid = 3496, comm = ifconfig kernel BUG at net/core/dev.c:1328! enter ? for help [c0000000be3d3760] d00000000026b014 .s2io_change_mtu+0x1c4/0x27c [s2io] [c0000000be3d3800] c0000000003631ac .dev_set_mtu+0x68/0xb0 [c0000000be3d3880] c000000000364bc4 .dev_ioctl+0x67c/0x780 [c0000000be3d3990] c000000000354394 .sock_ioctl+0x2d8/0x310 [c0000000be3d3a30] c0000000001054b4 .vfs_ioctl+0x5c/0xf0 [c0000000be3d3ad0] c000000000105954 .do_vfs_ioctl+0x40c/0x448 [c0000000be3d3b80] c000000000105a00 .sys_ioctl+0x70/0xb4 [c0000000be3d3c30] c00000000013a2e8 .dev_ifsioc+0x1b0/0x3e4 [c0000000be3d3d40] c0000000001398a8 .compat_sys_ioctl+0x3d4/0x468 [c0000000be3d3e30] c0000000000086b4 syscall_exit+0x0/0x40 --- Exception: c00 (System Call) at 000000000ff15fe8 SP (ffecf8a0) is in userspace And the code which is causing the bug is the following: void __netif_schedule(struct Qdisc *q) { BUG_ON(q == &noop_qdisc); So, somehow we're reaching __netif_schedule() using a noop_qdisc. -- Breno Leitao leitao@linux.vnet.ibm.com