Return-path: Received: from mga09.intel.com ([134.134.136.24]:62141 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751817Ab2GRRgh convert rfc822-to-8bit (ORCPT ); Wed, 18 Jul 2012 13:36:37 -0400 From: "Rustad, Mark D" To: Neil Horman CC: "Fastabend, John R" , "" , David Miller , "" , "" , "" Subject: Re: That's pretty much it for 3.5.0 Date: Wed, 18 Jul 2012 17:36:35 +0000 Message-ID: <205259E8-A99F-4573-96C9-7A394235B338@intel.com> (sfid-20120718_193649_831009_94903396) References: <5005D008.6060103@intel.com> <20120717.140241.1599386555723262095.davem@davemloft.net> <5005E390.7020706@intel.com> <20120717.151832.1306978935355646723.davem@davemloft.net> <5005F4F9.6010208@intel.com> <20120718130430.GE25563@hmsreliant.think-freely.org> In-Reply-To: <20120718130430.GE25563@hmsreliant.think-freely.org> Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Sender: linux-wireless-owner@vger.kernel.org List-ID: On Jul 18, 2012, at 6:04 AM, Neil Horman wrote: > John, can you post the backtrace you got for this? I replied to the patch that > you posted for this fix. the cgroup subsystem has an early_init flag thats > supposed to prevent the initialization of cgroups that don't need initialization > until later (like via module_init() calls). Here is the backtrace that I get and below a patch that fixes it: [ 0.010958] Initializing cgroup subsys net_prio [ 0.011040] BUG: unable to handle kernel NULL pointer dereference at 0000000000000828 [ 0.011998] IP: [] update_netdev_tables+0x68/0xe0 [ 0.011998] PGD 0 [ 0.011998] Oops: 0000 [#1] SMP [ 0.011998] CPU 0 [ 0.011998] Modules linked in: [ 0.011998] [ 0.011998] Pid: 0, comm: swapper/0 Not tainted 3.5.0-rc7-mdrlinux+ #10 Bochs Bochs [ 0.011998] RIP: 0010:[] [] update_netdev_tables+0x68/0xe0 [ 0.011998] RSP: 0000:ffffffff81a01e68 EFLAGS: 00010246 [ 0.011998] RAX: 0000000000000000 RBX: fffffffffffffed0 RCX: 0000000000000000 [ 0.011998] RDX: 0000000000000006 RSI: 2222222222222222 RDI: 2222222222222222 [ 0.011998] RBP: ffffffff81a01e88 R08: 2222222222222222 R09: 2222222222222222 [ 0.011998] R10: 0000000000000000 R11: 0000000000000001 R12: 0000000000000001 [ 0.011998] R13: 0000000000000000 R14: ffff88007ff608c0 R15: 00000000000143d0 [ 0.011998] FS: 0000000000000000(0000) GS:ffff88007fc00000(0000) knlGS:0000000000000000 [ 0.011998] CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b [ 0.011998] CR2: 0000000000000828 CR3: 0000000001a0b000 CR4: 00000000000006b0 [ 0.011998] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 0.011998] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 [ 0.011998] Process swapper/0 (pid: 0, threadinfo ffffffff81a00000, task ffffffff81a13420) [ 0.011998] Stack: [ 0.011998] ffffffff81a88020 0000000000000000 ffff88007d3a38f0 fffffffffffffff4 [ 0.011998] ffffffff81a01ec8 ffffffff814203cd ffff88007ff608c0 ffffffff817d8e9a [ 0.011998] ffffffff81a88cd8 ffffffff81a88020 ffffffff81a88020 ffffffff81b010a0 [ 0.011998] Call Trace: [ 0.011998] [] cgrp_create+0x8d/0xc0 [ 0.011998] [] cgroup_init_subsys+0x80/0x126 [ 0.011998] [] cgroup_init+0x36/0x117 [ 0.011998] [] start_kernel+0x32e/0x34f [ 0.011998] [] ? repair_env_string+0x5a/0x5a [ 0.011998] [] x86_64_start_reservations+0x101/0x105 [ 0.011998] [] ? early_idt_handlers+0x120/0x120 [ 0.011998] [] x86_64_start_kernel+0xcd/0xdc [ 0.011998] Code: 0f 1f 00 48 8b 83 30 01 00 00 48 8d 98 d0 fe ff ff 48 3d a8 e8 52 82 74 3a e8 25 db c3 ff 85 c0 74 09 80 3d bb 3d 68 00 00 74 40 <48> 8b 83 58 09 00 00 48 85 c0 74 cc 44 3b 60 10 76 c6 44 89 e6 [ 0.011998] RIP [] update_netdev_tables+0x68/0xe0 [ 0.011998] RSP [ 0.011998] CR2: 0000000000000828 [ 0.012009] ---[ end trace a7919e7f17c0a725 ]--- [ 0.012601] Kernel panic - not syncing: Attempted to kill the idle task! The following change simply statically initializes init_net.dev_base_head. I copied and pasted it into the email, so this rendering may not work, but I can send it if this approach looks reasonable. I have verified that it resolves the issue above. diff --git a/net/core/dev.c b/net/core/dev.c index 0f28a9e..db1ba61 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -6283,8 +6283,6 @@ static struct hlist_head *netdev_create_hash(void) /* Initialize per network namespace state */ static int __net_init netdev_init(struct net *net) { - INIT_LIST_HEAD(&net->dev_base_head); - net->dev_name_head = netdev_create_hash(); if (net->dev_name_head == NULL) goto err_name; diff --git a/net/core/net_namespace.c b/net/core/net_namespace.c index dddbacb..42f1e1c 100644 --- a/net/core/net_namespace.c +++ b/net/core/net_namespace.c @@ -27,7 +27,9 @@ static DEFINE_MUTEX(net_mutex); LIST_HEAD(net_namespace_list); EXPORT_SYMBOL_GPL(net_namespace_list); -struct net init_net; +struct net init_net = { + .dev_base_head = LIST_HEAD_INIT(init_net.dev_base_head), +}; EXPORT_SYMBOL(init_net); #define INITIAL_NET_GEN_PTRS 13 /* +1 for len +2 for rcu_head */ -- Mark Rustad, LAN Access Division, Intel Corporation