Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760238Ab2JYTiR (ORCPT ); Thu, 25 Oct 2012 15:38:17 -0400 Received: from rcsinet15.oracle.com ([148.87.113.117]:24128 "EHLO rcsinet15.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1760210Ab2JYTiO (ORCPT ); Thu, 25 Oct 2012 15:38:14 -0400 Message-ID: <50899507.1040900@oracle.com> Date: Thu, 25 Oct 2012 15:37:43 -0400 From: Sasha Levin User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:16.0) Gecko/20121024 Thunderbird/16.0.1 MIME-Version: 1.0 To: Greg Kroah-Hartman , Alan Cox , Jiri Slaby , "linux-kernel@vger.kernel.org" CC: Dave Jones Subject: tty, vt: lockdep warnings Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit X-Source-IP: ucsinet21.oracle.com [156.151.31.93] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 7189 Lines: 119 Hi all, While fuzzing with trinity inside a KVM tools (lkvm) guest running latest -next kernel, I've stumbled on the following spew: [ 603.081796] ====================================================== [ 603.081797] [ INFO: possible circular locking dependency detected ] [ 603.081800] 3.7.0-rc2-next-20121025-sasha-00001-g673f98e-dirty #77 Tainted: G W [ 603.081801] ------------------------------------------------------- [ 603.081802] kworker/0:1/902 is trying to acquire lock: [ 603.081815] ((fb_notifier_list).rwsem){.+.+.+}, at: [] __blocking_notifier_call_chain+0x7f/0xc0 [ 603.081815] [ 603.081815] but task is already holding lock: [ 603.081822] (console_lock){+.+.+.}, at: [] console_callback+0xe/0x130 [ 603.081823] [ 603.081823] which lock already depends on the new lock. [ 603.081823] [ 603.081824] [ 603.081824] the existing dependency chain (in reverse order) is: [ 603.081827] [ 603.081827] -> #1 (console_lock){+.+.+.}: [ 603.081832] [] lock_acquire+0x1aa/0x240 [ 603.081837] [] console_lock+0x68/0x70 [ 603.081841] [] register_con_driver+0x1b/0x110 [ 603.081844] [] take_over_console+0x29/0x60 [ 603.081848] [] fbcon_takeover+0x63/0xc0 [ 603.081851] [] fbcon_event_notify+0x33f/0x730 [ 603.081854] [] notifier_call_chain+0xee/0x130 [ 603.081857] [] __blocking_notifier_call_chain+0x98/0xc0 [ 603.081860] [] blocking_notifier_call_chain+0x11/0x20 [ 603.081863] [] fb_notifier_call_chain+0x16/0x20 [ 603.081866] [] register_framebuffer+0x24d/0x290 [ 603.081871] [] vga16fb_probe+0x1c0/0x227 [ 603.081876] [] platform_drv_probe+0x12/0x20 [ 603.081879] [] driver_probe_device+0x155/0x340 [ 603.081881] [] __device_attach+0x2e/0x50 [ 603.081884] [] bus_for_each_drv+0x56/0xa0 [ 603.081887] [] device_attach+0x88/0xc0 [ 603.081889] [] bus_probe_device+0x36/0xd0 [ 603.081892] [] device_add+0x4df/0x750 [ 603.081895] [] platform_device_add+0x1e8/0x280 [ 603.081900] [] vga16fb_init+0x8d/0xbb [ 603.081905] [] do_one_initcall+0x7a/0x135 [ 603.081908] [] kernel_init+0x299/0x470 [ 603.081912] [] ret_from_fork+0x7c/0xb0 [ 603.081915] [ 603.081915] -> #0 ((fb_notifier_list).rwsem){.+.+.+}: [ 603.081918] [] __lock_acquire+0x14df/0x1ca0 [ 603.081921] [] lock_acquire+0x1aa/0x240 [ 603.081924] [] down_read+0x47/0x90 [ 603.081927] [] __blocking_notifier_call_chain+0x7f/0xc0 [ 603.081930] [] blocking_notifier_call_chain+0x11/0x20 [ 603.081932] [] fb_notifier_call_chain+0x16/0x20 [ 603.081934] [] fb_blank+0x36/0xa0 [ 603.081938] [] fbcon_blank+0x14e/0x2d0 [ 603.081941] [] do_blank_screen+0x1b3/0x2b0 [ 603.081943] [] console_callback+0xc3/0x130 [ 603.081946] [] process_one_work+0x3b9/0x770 [ 603.081949] [] worker_thread+0x2ba/0x3f0 [ 603.081951] [] kthread+0xe3/0xf0 [ 603.081954] [] ret_from_fork+0x7c/0xb0 [ 603.081955] [ 603.081955] other info that might help us debug this: [ 603.081955] [ 603.081956] Possible unsafe locking scenario: [ 603.081956] [ 603.081956] CPU0 CPU1 [ 603.081957] ---- ---- [ 603.081959] lock(console_lock); [ 603.081961] lock((fb_notifier_list).rwsem); [ 603.081962] lock(console_lock); [ 603.081964] lock((fb_notifier_list).rwsem); [ 603.081964] [ 603.081964] *** DEADLOCK *** [ 603.081964] [ 603.081966] 3 locks held by kworker/0:1/902: [ 603.081971] #0: (events){.+.+.+}, at: [] process_one_work+0x268/0x770 [ 603.081976] #1: (console_work){+.+...}, at: [] process_one_work+0x268/0x770 [ 603.081981] #2: (console_lock){+.+.+.}, at: [] console_callback+0xe/0x130 [ 603.081981] [ 603.081981] stack backtrace: [ 603.081984] Pid: 902, comm: kworker/0:1 Tainted: G W 3.7.0-rc2-next-20121025-sasha-00001-g673f98e-dirty #77 [ 603.081985] Call Trace: [ 603.081990] [] print_circular_bug+0x1fb/0x20c [ 603.081994] [] __lock_acquire+0x14df/0x1ca0 [ 603.081997] [] ? __bfs+0x16a/0x220 [ 603.082000] [] lock_acquire+0x1aa/0x240 [ 603.082003] [] ? __blocking_notifier_call_chain+0x7f/0xc0 [ 603.082005] [] down_read+0x47/0x90 [ 603.082009] [] ? __blocking_notifier_call_chain+0x7f/0xc0 [ 603.082011] [] __blocking_notifier_call_chain+0x7f/0xc0 [ 603.082014] [] blocking_notifier_call_chain+0x11/0x20 [ 603.082017] [] fb_notifier_call_chain+0x16/0x20 [ 603.082019] [] fb_blank+0x36/0xa0 [ 603.082022] [] fbcon_blank+0x14e/0x2d0 [ 603.082025] [] ? _raw_spin_unlock_irqrestore+0x5d/0xb0 [ 603.082028] [] ? trace_hardirqs_on+0xd/0x10 [ 603.082031] [] ? _raw_spin_unlock_irqrestore+0x84/0xb0 [ 603.082035] [] ? try_to_del_timer_sync+0x64/0x70 [ 603.082037] [] ? del_timer_sync+0xf8/0x130 [ 603.082039] [] ? del_timer_sync+0x38/0x130 [ 603.082042] [] do_blank_screen+0x1b3/0x2b0 [ 603.082045] [] console_callback+0xc3/0x130 [ 603.082048] [] process_one_work+0x3b9/0x770 [ 603.082050] [] ? process_one_work+0x268/0x770 [ 603.082053] [] ? work_fixup_activate+0x90/0x90 [ 603.082056] [] ? poke_blanked_console+0x100/0x100 [ 603.082059] [] worker_thread+0x2ba/0x3f0 [ 603.082061] [] ? rescuer_thread+0x2d0/0x2d0 [ 603.082063] [] kthread+0xe3/0xf0 [ 603.082066] [] ? put_lock_stats.isra.16+0xe/0x40 [ 603.082069] [] ? insert_kthread_work+0x90/0x90 [ 603.082072] [] ret_from_fork+0x7c/0xb0 [ 603.082074] [] ? insert_kthread_work+0x90/0x90 -- 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/