From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754611Ab2IYJqu (ORCPT ); Tue, 25 Sep 2012 05:46:50 -0400 Received: from mail-ee0-f46.google.com ([74.125.83.46]:61485 "EHLO mail-ee0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753105Ab2IYJqs (ORCPT ); Tue, 25 Sep 2012 05:46:48 -0400 Message-ID: <50617D95.7010005@gmail.com> Date: Tue, 25 Sep 2012 11:47:01 +0200 From: Sasha Levin User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:15.0) Gecko/20120913 Thunderbird/15.0.1 MIME-Version: 1.0 To: Jiri Slaby CC: Sasha Levin , Alan Cox , Greg Kroah-Hartman , Dave Jones , "linux-kernel@vger.kernel.org" Subject: Re: tty ldisc lockups in linux-next References: <50617008.5000207@oracle.com> <506170BB.4040005@suse.cz> <50617171.8030601@gmail.com> <506171DA.9070102@suse.cz> In-Reply-To: <506171DA.9070102@suse.cz> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 09/25/2012 10:56 AM, Jiri Slaby wrote: > On 09/25/2012 10:55 AM, Sasha Levin wrote: >> On 09/25/2012 10:52 AM, Jiri Slaby wrote: >>>> Hi all, >>>>> >>>>> While fuzzing with trinity in a KVM tools guest running linux-next kernel, I keep hitting the following lockup: >>> Hi, I'm confused here. Is this different to what you reported a couple >>> days ago? Doesn't reverting aa3c8af86382 help in the end? >> >> I was just about to send a reply to that mail saying that while reverting aa3c8af86382 reduces the odds for seeing it, it still >> happens. You were faster than me :) >> >> But yes, it still happens even if I revert aa3c8af86382 or try applying your patch in that thread. > > The patch won't help, it's kind of certain. > > Instead I still wonder what process sits on the terminal. Could you > investigate? > It looks like sh is trying to read: [ 606.950194] sh S 0000000000000001 4800 6260 1 0x00000000 [ 606.950194] ffff88000c0ddcc8 0000000000000082 ffffffff847baa68 0000000000000b02 [ 606.950194] ffff88000c0ddfd8 ffff88000c0ddfd8 ffff88000c0ddfd8 ffff88000c0ddfd8 [ 606.950194] ffff88000f578000 ffff88000c0bb000 ffff88000c0ddd98 ffff880040b4d000 [ 606.950194] Call Trace: [ 606.950194] [] schedule+0x55/0x60 [ 606.950194] [] schedule_timeout+0x45/0x360 [ 606.950194] [] ? _raw_spin_unlock_irqrestore+0x5d/0xb0 [ 606.950194] [] ? trace_hardirqs_on+0xd/0x10 [ 606.950194] [] ? _raw_spin_unlock_irqrestore+0x84/0xb0 [ 606.950194] [] n_tty_read+0x4c1/0x9a0 [ 606.950194] [] ? _raw_spin_unlock_irqrestore+0x5d/0xb0 [ 606.950194] [] ? try_to_wake_up+0x360/0x360 [ 606.950194] [] tty_read+0x8f/0x100 [ 606.950194] [] vfs_read+0xad/0x180 [ 606.950194] [] sys_read+0x50/0xa0 [ 606.950194] [] system_call_fastpath+0x1a/0x1f While init is trying to exit: [ 605.524940] init D ffff88000d5b0000 3376 1 0 0x00000002 [ 605.527502] ffff88000d5adc28 0000000000000082 ffff88000d5adbe8 ffffffff81150ac5 [ 605.529685] ffff88000d5adfd8 ffff88000d5adfd8 ffff88000d5adfd8 ffff88000d5adfd8 [ 605.530939] ffff88000d613000 ffff88000d5b0000 ffff88000d5b08f0 7fffffffffffffff [ 605.532064] Call Trace: [ 605.532064] [] ? sched_clock_local+0x25/0xa0 [ 605.532064] [] schedule+0x55/0x60 [ 605.532064] [] schedule_timeout+0x45/0x360 [ 605.532064] [] ? _raw_spin_unlock_irqrestore+0x5d/0xb0 [ 605.532064] [] ? trace_hardirqs_on+0xd/0x10 [ 605.532064] [] ? _raw_spin_unlock_irqrestore+0x84/0xb0 [ 605.532064] [] ? prepare_to_wait+0x77/0x90 [ 605.532064] [] tty_ldisc_wait_idle.isra.7+0x76/0xb0 [ 605.532064] [] ? abort_exclusive_wait+0xb0/0xb0 [ 605.532064] [] tty_ldisc_hangup+0x1cb/0x320 [ 605.532064] [] ? __tty_hangup+0x122/0x430 [ 605.532064] [] __tty_hangup+0x12a/0x430 [ 605.532064] [] ? _raw_spin_unlock_irqrestore+0x84/0xb0 [ 605.532064] [] disassociate_ctty+0x6c/0x230 [ 605.532064] [] do_exit+0x3d8/0xa90 [ 605.532064] [] ? retint_swapgs+0x13/0x1b [ 605.532064] [] do_group_exit+0x84/0xd0 [ 605.532064] [] sys_exit_group+0x12/0x20 [ 605.532064] [] system_call_fastpath+0x1a/0x1f And the corresponding lock info: [ 606.950194] Showing all locks held in the system: [ 606.950194] 1 lock held by init/1: [ 606.950194] #0: (&tty->ldisc_mutex){+.+.+.}, at: [] tty_ldisc_hangup+0x122/0x320 [ 606.950194] 1 lock held by sh/6260: [ 606.950194] #0: (&tty->atomic_read_lock){+.+...}, at: [] n_tty_read+0x2c8/0x9a0