Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757293Ab3DXSsN (ORCPT ); Wed, 24 Apr 2013 14:48:13 -0400 Received: from aserp1040.oracle.com ([141.146.126.69]:23723 "EHLO aserp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756676Ab3DXSsL (ORCPT ); Wed, 24 Apr 2013 14:48:11 -0400 Message-ID: <517828C0.6090802@oracle.com> Date: Wed, 24 Apr 2013 14:47:28 -0400 From: Sasha Levin User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130408 Thunderbird/17.0.5 MIME-Version: 1.0 To: Peter Zijlstra , Ingo Molnar CC: "linux-kernel@vger.kernel.org" Subject: lockdep: oops while dumping locks Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit X-Source-IP: acsinet21.oracle.com [141.146.126.237] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 6166 Lines: 97 Hi all, I've noticed that sometimes lockdep would spew a warning and an oops while dumping the list of held locks. I'm not quite sure why it happens and I didn't find anything that was recently changed in the code that could cause that: [ 855.807172] Showing all locks held in the system: [ 855.809162] 2 locks held by khungtaskd/3552: [ 855.809729] #0: (rcu_read_lock){.+.+..}, at: [] watchdog+0x73/0x490 [ 855.810956] #1: (tasklist_lock){.+.+..}, at: [] debug_show_all_locks+0x5c/0x260 [ 855.815299] 1 lock held by ksmd/3578: [ 855.815770] #0: (ksm_thread_mutex){+.+.+.}, at: [] ksm_scan_thread+0x4e/0x310 [ 855.817055] 2 locks held by kpktgend_5/7480: [ 855.817597] #0: (rcu_read_lock){.+.+..}, at: [< (null)>] (null) [ 855.821794] #1: [ 855.822044] ------------[ cut here ]------------ [ 855.822677] WARNING: at kernel/lockdep.c:146 hlock_class+0x50/0x80() [ 855.823477] DEBUG_LOCKS_WARN_ON(1) [ 855.827953] Modules linked in: [ 855.828423] CPU: 1 PID: 3552 Comm: khungtaskd Tainted: G W 3.9.0-rc8-next-20130423-sasha-00014-gdf37a98 #352 [ 855.829749] 0000000000000009 ffff8800b8e05c28 ffffffff83fb6095 ffff8800b8e05c68 [ 855.830798] ffffffff811142db 00000000b58a3000 ffff8800adee0950 0000000000000002 [ 855.835860] 0000000000000002 ffff8800b58a3000 ffff8800afa18000 ffff8800b8e05cc8 [ 855.836887] Call Trace: [ 855.837222] [] dump_stack+0x19/0x1b [ 855.840950] [] warn_slowpath_common+0x6b/0xa0 [ 855.841734] [] warn_slowpath_fmt+0x41/0x50 [ 855.842472] [] ? printk+0x48/0x4a [ 855.843106] [] hlock_class+0x50/0x80 [ 855.843758] [] print_lock+0xe/0x3d [ 855.847471] [] lockdep_print_held_locks+0xa2/0xe0 [ 855.848561] [] debug_show_all_locks+0x11a/0x260 [ 855.849351] [] show_state_filter+0x207/0x220 [ 855.850141] [] ? sched_show_task+0x270/0x270 [ 855.853945] [] ? lockdep_print_held_locks+0xa2/0xe0 [ 855.854756] [] ? sched_show_task+0xa2/0x270 [ 855.855476] [] watchdog+0x313/0x490 [ 855.856107] [] ? watchdog+0x73/0x490 [ 855.856739] [] ? hung_task_panic+0x20/0x20 [ 855.862510] [] kthread+0xe3/0xf0 [ 855.863119] [] ? kthread_create_on_node+0x160/0x160 [ 855.863917] [] ret_from_fork+0x7c/0xb0 [ 855.864575] [] ? kthread_create_on_node+0x160/0x160 [ 855.868426] ---[ end trace 3adc9bd194fdba9a ]--- [ 855.869001] BUG: unable to handle kernel NULL pointer dereference at 0000000000000030 [ 855.869983] IP: [] __print_lock_name+0xc0/0xc0 [ 855.870744] PGD 0 [ 855.872483] Oops: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC [ 855.872483] Dumping ftrace buffer: [ 855.872483] (ftrace buffer empty) [ 855.872483] Modules linked in: [ 855.872483] CPU: 1 PID: 3552 Comm: khungtaskd Tainted: G W 3.9.0-rc8-next-20130423-sasha-00014-gdf37a98 #352 [ 855.872483] task: ffff8800b58a3000 ti: ffff8800b8e04000 task.ti: ffff8800b8e04000 [ 855.872483] RIP: 0010:[] [] __print_lock_name+0xc0/0xc0 [ 855.872483] RSP: 0018:ffff8800b8e05cb0 EFLAGS: 00010296 [ 855.872483] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 000000008a728a71 [ 855.872483] RDX: ffff8800b58a3000 RSI: ffff8800b8e05cc1 RDI: 0000000000000000 [ 855.872483] RBP: ffff8800b8e05cd8 R08: 0000000000000002 R09: 0000000000000000 [ 855.872483] R10: 0000000000000001 R11: 0000000000000000 R12: 0000000000000002 [ 855.890101] R13: 0000000000000002 R14: ffff8800b58a3000 R15: ffff8800afa18000 [ 855.891151] FS: 0000000000000000(0000) GS:ffff8800bb600000(0000) knlGS:0000000000000000 [ 855.891151] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 855.891151] CR2: 0000000000000030 CR3: 0000000005826000 CR4: 00000000000406e0 [ 855.891151] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 855.891151] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 [ 855.891151] Stack: [ 855.891151] ffffffff81189bb5 0000000000000002 0000000000000002 ffff8800b8e05cd8 [ 855.891151] ffff8800adee0950 ffff8800b8e05cf8 ffffffff83fab45b 0000000000000038 [ 855.891151] ffff8800adee0000 ffff8800b8e05d28 ffffffff81189c92 ffff8800b8e05d28 [ 855.891151] Call Trace: [ 855.891151] [] ? print_lock_name+0x15/0x50 [ 855.891151] [] print_lock+0x16/0x3d [ 855.891151] [] lockdep_print_held_locks+0xa2/0xe0 [ 855.891151] [] debug_show_all_locks+0x11a/0x260 [ 855.891151] [] show_state_filter+0x207/0x220 [ 855.900353] [] ? sched_show_task+0x270/0x270 [ 855.900353] [] ? lockdep_print_held_locks+0xa2/0xe0 [ 855.900353] [] ? sched_show_task+0xa2/0x270 [ 855.900353] [] watchdog+0x313/0x490 [ 855.900353] [] ? watchdog+0x73/0x490 [ 855.900353] [] ? hung_task_panic+0x20/0x20 [ 855.900353] [] kthread+0xe3/0xf0 [ 855.900353] [] ? kthread_create_on_node+0x160/0x160 [ 855.900353] [] ret_from_fork+0x7c/0xb0 [ 855.900353] [] ? kthread_create_on_node+0x160/0x160 [ 855.900353] Code: 0f 1f 00 48 8b 45 e8 65 48 33 04 25 28 00 00 00 74 09 e8 d4 a6 f8 ff 0f 1f 40 00 48 81 c4 98 00 00 00 5b 5d c3 66 0f 1f 44 00 00 <48> 8b 47 30 55 48 89 e5 a8 04 0f 85 a3 00 00 00 83 e0 01 f7 d8 [ 855.900353] RIP [] __print_lock_name+0xc0/0xc0 [ 855.900353] RSP [ 855.900353] CR2: 0000000000000030 [ 856.494698] ---[ end trace 3adc9bd194fdba9b ]--- -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/