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SubjectRe: [2.6.33-rc5] starting emacs makes lockdep warning
From
On Tue, Jan 26, 2010 at 11:20 AM, KOSAKI Motohiro
<kosaki.motohiro@jp.fujitsu.com> wrote:
> Hi
>
> Current linus tree made following lockdep warning when starting emacs command.
> Is this known issue?
>
>
> =========================================================
> [ INFO: possible irq lock inversion dependency detected ]
> 2.6.33-rc5 #77
> ---------------------------------------------------------
> emacs/1609 just changed the state of lock:
>  (&(&tty->ctrl_lock)->rlock){+.....}, at: [<ffffffff8127c648>] tty_fasync+0xe8/0x190
> but this lock took another, HARDIRQ-unsafe lock in the past:
>  (&(&sighand->siglock)->rlock){-.....}
>
> and interrupts could create inverse lock ordering between them.
>
>

Hey,

does reverting commit 703625118 help?



> other info that might help us debug this:
> 1 lock held by emacs/1609:
>  #0:  (&(&tty->ctrl_lock)->rlock){+.....}, at: [<ffffffff8127c648>] tty_fasync+0xe8/0x190
>
> the shortest dependencies between 2nd lock and 1st lock:
>  -> (&(&sighand->siglock)->rlock){-.....} ops: 50393 {
>    IN-HARDIRQ-W at:
>                          [<ffffffff8108924e>] __lock_acquire+0x7ae/0x15a0
>                          [<ffffffff8108a0df>] lock_acquire+0x9f/0x120
>                          [<ffffffff81423012>] _raw_spin_lock_irqsave+0x52/0x90
>                          [<ffffffff81065799>] lock_task_sighand+0x79/0x100
>                          [<ffffffff8106600f>] do_send_sig_info+0x3f/0x90
>                          [<ffffffff810660f0>] group_send_sig_info+0x40/0x50
>                          [<ffffffff81066703>] kill_pid_info+0x73/0xe0
>                          [<ffffffff81054014>] it_real_fn+0x44/0xa0
>                          [<ffffffff81075d1e>] __run_hrtimer+0x8e/0x1e0
>                          [<ffffffff81076116>] hrtimer_interrupt+0xe6/0x250
>                          [<ffffffff8142a0b9>] smp_apic_timer_interrupt+0x69/0x9b
>                          [<ffffffff81003a93>] apic_timer_interrupt+0x13/0x20
>                          [<ffffffff81001956>] cpu_idle+0x66/0xd0
>                          [<ffffffff814082e2>] rest_init+0x92/0xa0
>                          [<ffffffff81b4cd84>] start_kernel+0x3b9/0x3c5
>                          [<ffffffff81b4c310>] x86_64_start_reservations+0x120/0x124
>                          [<ffffffff81b4c3f8>] x86_64_start_kernel+0xe4/0xeb
>    INITIAL USE at:
>                         [<ffffffff81088e86>] __lock_acquire+0x3e6/0x15a0
>                         [<ffffffff8108a0df>] lock_acquire+0x9f/0x120
>                         [<ffffffff81423012>] _raw_spin_lock_irqsave+0x52/0x90
>                         [<ffffffff810646dc>] flush_signals+0x2c/0x60
>                         [<ffffffff81064743>] ignore_signals+0x33/0x40
>                         [<ffffffff81071067>] kthreadd+0x37/0x180
>                         [<ffffffff81003ed4>] kernel_thread_helper+0x4/0x10
>  }
>  ... key      at: [<ffffffff81c054a4>] __key.46539+0x0/0x8
>  ... acquired at:
>   [<ffffffff81089af6>] __lock_acquire+0x1056/0x15a0
>   [<ffffffff8108a0df>] lock_acquire+0x9f/0x120
>   [<ffffffff81423012>] _raw_spin_lock_irqsave+0x52/0x90
>   [<ffffffff8127c1be>] __proc_set_tty+0x3e/0x150
>   [<ffffffff8127e01d>] tty_open+0x51d/0x5e0
>   [<ffffffff81142400>] chrdev_open+0x170/0x290
>   [<ffffffff8113c561>] __dentry_open+0x131/0x3a0
>   [<ffffffff8113c8e4>] nameidata_to_filp+0x54/0x70
>   [<ffffffff8114c098>] do_filp_open+0x948/0xcd0
>   [<ffffffff8113c2e9>] do_sys_open+0x69/0x140
>   [<ffffffff8113c400>] sys_open+0x20/0x30
>   [<ffffffff8100309b>] system_call_fastpath+0x16/0x1b
>
> -> (&(&tty->ctrl_lock)->rlock){+.....} ops: 191 {
>   HARDIRQ-ON-W at:
>                        [<ffffffff81087e63>] mark_held_locks+0x73/0xa0
>                        [<ffffffff810880bb>] trace_hardirqs_on_caller+0x7b/0x1c0
>                        [<ffffffff8108820d>] trace_hardirqs_on+0xd/0x10
>                        [<ffffffff81423730>] _raw_write_unlock_irq+0x30/0x60
>                        [<ffffffff8114cc63>] f_modown+0x53/0xe0
>                        [<ffffffff8114cd1e>] __f_setown+0xe/0x20
>                        [<ffffffff8127c667>] tty_fasync+0x107/0x190
>                        [<ffffffff8114d842>] sys_fcntl+0x222/0x580
>                        [<ffffffff8100309b>] system_call_fastpath+0x16/0x1b
>   INITIAL USE at:
>                       [<ffffffff81088e86>] __lock_acquire+0x3e6/0x15a0
>                       [<ffffffff8108a0df>] lock_acquire+0x9f/0x120
>                       [<ffffffff81423012>] _raw_spin_lock_irqsave+0x52/0x90
>                       [<ffffffff8127c1be>] __proc_set_tty+0x3e/0x150
>                       [<ffffffff8127e01d>] tty_open+0x51d/0x5e0
>                       [<ffffffff81142400>] chrdev_open+0x170/0x290
>                       [<ffffffff8113c561>] __dentry_open+0x131/0x3a0
>                       [<ffffffff8113c8e4>] nameidata_to_filp+0x54/0x70
>                       [<ffffffff8114c098>] do_filp_open+0x948/0xcd0
>                       [<ffffffff8113c2e9>] do_sys_open+0x69/0x140
>                       [<ffffffff8113c400>] sys_open+0x20/0x30
>                       [<ffffffff8100309b>] system_call_fastpath+0x16/0x1b
>  }
>  ... key      at: [<ffffffff82533fb8>] __key.30033+0x0/0x8
>  ... acquired at:
>   [<ffffffff81087263>] check_usage_backwards+0x93/0x100
>   [<ffffffff81087b9a>] mark_lock+0x1ca/0x420
>   [<ffffffff81087e63>] mark_held_locks+0x73/0xa0
>   [<ffffffff810880bb>] trace_hardirqs_on_caller+0x7b/0x1c0
>   [<ffffffff8108820d>] trace_hardirqs_on+0xd/0x10
>   [<ffffffff81423730>] _raw_write_unlock_irq+0x30/0x60
>   [<ffffffff8114cc63>] f_modown+0x53/0xe0
>   [<ffffffff8114cd1e>] __f_setown+0xe/0x20
>   [<ffffffff8127c667>] tty_fasync+0x107/0x190
>   [<ffffffff8114d842>] sys_fcntl+0x222/0x580
>   [<ffffffff8100309b>] system_call_fastpath+0x16/0x1b
>
>
> stack backtrace:
> Pid: 1609, comm: emacs Not tainted 2.6.33-rc5 #77
> Call Trace:
>  [<ffffffff810870bd>] print_irq_inversion_bug.clone.0+0x12d/0x140
>  [<ffffffff810871d0>] ? check_usage_backwards+0x0/0x100
>  [<ffffffff81087263>] check_usage_backwards+0x93/0x100
>  [<ffffffff8114cc4c>] ? f_modown+0x3c/0xe0
>  [<ffffffff81087b9a>] mark_lock+0x1ca/0x420
>  [<ffffffff81087e63>] mark_held_locks+0x73/0xa0
>  [<ffffffff81423730>] ? _raw_write_unlock_irq+0x30/0x60
>  [<ffffffff810880bb>] trace_hardirqs_on_caller+0x7b/0x1c0
>  [<ffffffff8108820d>] trace_hardirqs_on+0xd/0x10
>  [<ffffffff81423730>] _raw_write_unlock_irq+0x30/0x60
>  [<ffffffff8114cc63>] f_modown+0x53/0xe0
>  [<ffffffff8114cd1e>] __f_setown+0xe/0x20
>  [<ffffffff8127c667>] tty_fasync+0x107/0x190
>  [<ffffffff8114d842>] sys_fcntl+0x222/0x580
>  [<ffffffff8100309b>] system_call_fastpath+0x16/0x1b
>
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