May 31 16:19:06 BSW-2-BRASWELL kernel: [ 3221.293850] Console: switching to colour dummy device 80x25 May 31 16:19:06 BSW-2-BRASWELL kernel: [ 3221.328134] gem_exec_reloc (1680): drop_caches: 4 May 31 16:19:09 BSW-2-BRASWELL kernel: [ 3224.608684] Console: switching to colour frame buffer device 240x67 May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.325196] May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.325337] ====================================================== May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.325613] WARNING: possible circular locking dependency detected May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.325889] 4.12.0-rc3-drm-tip-ww22-commit-4aa1d46+ #1 Not tainted May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.326159] ------------------------------------------------------ May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.326430] kworker/u8:1/1675 is trying to acquire lock: May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.326663] (&buf->lock){+.+...}, at: [] tty_buffer_flush+0x32/0xa0 May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.327038] May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.327038] but task is already holding lock: May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.327293] (&o_tty->termios_rwsem/1){++++..}, at: [] isig+0x3c/0xf0 May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.327663] May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.327663] which lock already depends on the new lock. May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.327663] May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.328010] May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.328010] the existing dependency chain (in reverse order) is: May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.328330] May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.328330] -> #2 (&o_tty->termios_rwsem/1){++++..}: May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.328644] lock_acquire+0x9e/0x1e0 May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.328838] down_read+0x39/0x60 May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.329017] n_tty_write+0x8a/0x470 May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.329204] tty_write+0x1a6/0x320 May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.329393] __vfs_write+0x23/0x120 May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.329578] vfs_write+0xc5/0x1d0 May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.329758] SyS_write+0x44/0xb0 May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.329938] entry_SYSCALL_64_fastpath+0x1c/0xb1 May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.330165] May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.330165] -> #1 (&tty->atomic_write_lock){+.+.+.}: May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.330471] lock_acquire+0x9e/0x1e0 May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.330663] __mutex_lock+0x83/0x980 May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.330855] mutex_lock_nested+0x16/0x20 May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.331063] tty_port_default_receive_buf+0x43/0x90 May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.331307] flush_to_ldisc+0x9c/0xb0 May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.331505] process_one_work+0x1fe/0x670 May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.331714] worker_thread+0x49/0x3b0 May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.331909] kthread+0x10f/0x150 May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.332088] ret_from_fork+0x27/0x40 May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.332273] May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.332273] -> #0 (&buf->lock){+.+...}: May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.332532] __lock_acquire+0x15a0/0x1790 May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.332741] lock_acquire+0x9e/0x1e0 May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.332933] __mutex_lock+0x83/0x980 May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.333124] mutex_lock_nested+0x16/0x20 May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.333331] tty_buffer_flush+0x32/0xa0 May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.340959] pty_flush_buffer+0x22/0x80 May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.348609] tty_driver_flush_buffer+0x16/0x20 May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.356351] isig+0x90/0xf0 May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.364092] n_tty_receive_signal_char+0x17/0x60 May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.371950] n_tty_receive_char_special+0x8c9/0xad0 May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.379849] n_tty_receive_buf_common+0xa39/0xc60 May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.387798] n_tty_receive_buf2+0xf/0x20 May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.395765] tty_ldisc_receive_buf+0x1d/0x50 May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.403830] tty_port_default_receive_buf+0x54/0x90 May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.412003] flush_to_ldisc+0x9c/0xb0 May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.420208] process_one_work+0x1fe/0x670 May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.428459] worker_thread+0x49/0x3b0 May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.436763] kthread+0x10f/0x150 May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.445103] ret_from_fork+0x27/0x40 May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.453487] May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.453487] other info that might help us debug this: May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.453487] May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.478614] Chain exists of: May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.478614] &buf->lock --> &tty->atomic_write_lock --> &o_tty->termios_rwsem/1 May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.478614] May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.504762] Possible unsafe locking scenario: May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.504762] May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.522491] CPU0 CPU1 May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.531540] ---- ---- May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.540591] lock(&o_tty->termios_rwsem/1); May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.549545] lock(&tty->atomic_write_lock); May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.558611] lock(&o_tty->termios_rwsem/1); May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.567599] lock(&buf->lock); May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.576429] May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.576429] *** DEADLOCK *** May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.576429] May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.601753] 6 locks held by kworker/u8:1/1675: May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.610132] #0: ("events_unbound"){.+.+.+}, at: [] process_one_work+0x178/0x670 May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.618778] #1: ((&buf->work)){+.+...}, at: [] process_one_work+0x178/0x670 May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.627428] #2: (&port->buf.lock/1){+.+...}, at: [] flush_to_ldisc+0x20/0xb0 May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.636211] #3: (&tty->ldisc_sem){++++.+}, at: [] tty_ldisc_ref+0x1a/0x50 May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.645097] #4: (&tty->atomic_write_lock){+.+.+.}, at: [] tty_port_default_receive_buf+0x43/0x90 May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.654363] #5: (&o_tty->termios_rwsem/1){++++..}, at: [] isig+0x3c/0xf0 May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.663644] May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.663644] stack backtrace: May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.681734] CPU: 2 PID: 1675 Comm: kworker/u8:1 Not tainted 4.12.0-rc3-drm-tip-ww22-commit-4aa1d46+ #1 May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.691201] Hardware name: LENOVO 10G9000NUS/BRASWELL, BIOS M00KT33AUS 08/12/2015 May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.700817] Workqueue: events_unbound flush_to_ldisc May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.710489] Call Trace: May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.720132] dump_stack+0x67/0x97 May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.729816] print_circular_bug+0x1e0/0x2d0 May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.739565] __lock_acquire+0x15a0/0x1790 May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.749381] lock_acquire+0x9e/0x1e0 May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.759161] ? lock_acquire+0x9e/0x1e0 May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.768914] ? tty_buffer_flush+0x32/0xa0 May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.778644] ? tty_buffer_flush+0x32/0xa0 May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.788246] __mutex_lock+0x83/0x980 May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.797872] ? tty_buffer_flush+0x32/0xa0 May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.807521] ? isig+0x59/0xf0 May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.817096] ? tty_buffer_flush+0x32/0xa0 May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.826686] ? __mutex_lock+0x3b1/0x980 May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.836266] ? isig+0x88/0xf0 May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.845803] mutex_lock_nested+0x16/0x20 May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.855398] ? mutex_lock_nested+0x16/0x20 May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.865029] tty_buffer_flush+0x32/0xa0 May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.874666] pty_flush_buffer+0x22/0x80 May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.884293] tty_driver_flush_buffer+0x16/0x20 May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.893953] isig+0x90/0xf0 May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.903555] n_tty_receive_signal_char+0x17/0x60 May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.913299] n_tty_receive_char_special+0x8c9/0xad0 May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.923052] n_tty_receive_buf_common+0xa39/0xc60 May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.932799] n_tty_receive_buf2+0xf/0x20 May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.942516] tty_ldisc_receive_buf+0x1d/0x50 May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.952252] ? mutex_lock_nested+0x16/0x20 May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.961974] tty_port_default_receive_buf+0x54/0x90 May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.971738] flush_to_ldisc+0x9c/0xb0 May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.981494] process_one_work+0x1fe/0x670 May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3325.991284] worker_thread+0x49/0x3b0 May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3326.001078] kthread+0x10f/0x150 May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3326.010842] ? process_one_work+0x670/0x670 May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3326.020627] ? kthread_create_on_node+0x40/0x40 May 31 16:20:50 BSW-2-BRASWELL kernel: [ 3326.030400] ret_from_fork+0x27/0x40