Re: hung tasks in 3.18.0-rc1-00221-gc3351df

Paul E. McKenney
2014-10-24T00:22:16Z

On Thu, Oct 23, 2014 at 04:21:17PM +0300, Meelis Roos wrote:
> This is first real test on a computer where 3.17 did hang. Fist the hung
> task info, then full dmesg.
>
> [ 960.346611] INFO: task kworker/u16:0:6 blocked for more than 120 seconds.
> [ 960.346616] Tainted: G W 3.18.0-rc1-00221-gc3351df #150
> [ 960.346618] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
> [ 960.346621] kworker/u16:0 D 0000000000000000 0 6 2 0x00000000
> [ 960.346633] Workqueue: netns cleanup_net
> [ 960.346635] ffff880111c4d1e0 0000000000000002 ffff880111c4d1e0 ffff880111c53fd8
> [ 960.346639] ffff880111c4d1e0 000000000000a000 ffff880111c4d1e0 0000000000000296
> [ 960.346642] 0000000000000000 7fffffffffffffff 7fffffffffffffff ffffffff8182e010
> [ 960.346646] Call Trace:
> [ 960.346654] [<ffffffff8153dcfd>] ? schedule_timeout+0x18d/0x200
> [ 960.346660] [<ffffffff810915a0>] ? get_state_synchronize_rcu+0x10/0x10
> [ 960.346664] [<ffffffff8153c544>] ? wait_for_completion+0xb4/0x110
> [ 960.346669] [<ffffffff8153e5d5>] ? _raw_spin_unlock_irqrestore+0x5/0x10
> [ 960.346672] [<ffffffff8153c539>] ? wait_for_completion+0xa9/0x110
> [ 960.346677] [<ffffffff81069450>] ? wake_up_state+0x10/0x10
> [ 960.346681] [<ffffffff8109285a>] ? _rcu_barrier+0x14a/0x1d0
> [ 960.346686] [<ffffffff8145f13c>] ? netdev_run_todo+0x5c/0x310
> [ 960.346691] [<ffffffff81458775>] ? rollback_registered_many+0x265/0x2d0
> [ 960.346696] [<ffffffff81459db6>] ? default_device_exit_batch+0x136/0x150
> [ 960.346701] [<ffffffff8107a240>] ? __wake_up_sync+0x10/0x10
> [ 960.346704] [<ffffffff81454310>] ? cleanup_net+0xf0/0x1d0
> [ 960.346709] [<ffffffff8105b566>] ? process_one_work+0x136/0x380
> [ 960.346713] [<ffffffff81058ca7>] ? pwq_activate_delayed_work+0x27/0x40
> [ 960.346716] [<ffffffff8105ba83>] ? worker_thread+0x63/0x480
> [ 960.346720] [<ffffffff8105ba20>] ? rescuer_thread+0x270/0x270
> [ 960.346723] [<ffffffff8105fc9e>] ? kthread+0xce/0xf0
> [ 960.346726] [<ffffffff81060000>] ? queue_kthread_work+0x80/0x80
> [ 960.346729] [<ffffffff8105fbd0>] ? kthread_create_on_node+0x180/0x180
> [ 960.346734] [<ffffffff8153ed2c>] ? ret_from_fork+0x7c/0xb0
> [ 960.346737] [<ffffffff8105fbd0>] ? kthread_create_on_node+0x180/0x180
> [ 1080.363583] INFO: task kworker/u16:0:6 blocked for more than 120 seconds.
> [ 1080.363589] Tainted: G W 3.18.0-rc1-00221-gc3351df #150
> [ 1080.363591] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
> [ 1080.363594] kworker/u16:0 D 0000000000000000 0 6 2 0x00000000
> [ 1080.363604] Workqueue: netns cleanup_net
> [ 1080.363607] ffff880111c4d1e0 0000000000000002 ffff880111c4d1e0 ffff880111c53fd8
> [ 1080.363610] ffff880111c4d1e0 000000000000a000 ffff880111c4d1e0 0000000000000296
> [ 1080.363614] 0000000000000000 7fffffffffffffff 7fffffffffffffff ffffffff8182e010
> [ 1080.363617] Call Trace:
> [ 1080.363625] [<ffffffff8153dcfd>] ? schedule_timeout+0x18d/0x200
> [ 1080.363633] [<ffffffff810915a0>] ? get_state_synchronize_rcu+0x10/0x10
> [ 1080.363637] [<ffffffff8153c544>] ? wait_for_completion+0xb4/0x110
> [ 1080.363641] [<ffffffff8153e5d5>] ? _raw_spin_unlock_irqrestore+0x5/0x10
> [ 1080.363645] [<ffffffff8153c539>] ? wait_for_completion+0xa9/0x110
> [ 1080.363649] [<ffffffff81069450>] ? wake_up_state+0x10/0x10
> [ 1080.363653] [<ffffffff8109285a>] ? _rcu_barrier+0x14a/0x1d0
> [ 1080.363658] [<ffffffff8145f13c>] ? netdev_run_todo+0x5c/0x310
> [ 1080.363663] [<ffffffff81458775>] ? rollback_registered_many+0x265/0x2d0
> [ 1080.363667] [<ffffffff81459db6>] ? default_device_exit_batch+0x136/0x150
> [ 1080.363672] [<ffffffff8107a240>] ? __wake_up_sync+0x10/0x10
> [ 1080.363676] [<ffffffff81454310>] ? cleanup_net+0xf0/0x1d0
> [ 1080.363681] [<ffffffff8105b566>] ? process_one_work+0x136/0x380
> [ 1080.363684] [<ffffffff81058ca7>] ? pwq_activate_delayed_work+0x27/0x40
> [ 1080.363688] [<ffffffff8105ba83>] ? worker_thread+0x63/0x480
> [ 1080.363691] [<ffffffff8105ba20>] ? rescuer_thread+0x270/0x270
> [ 1080.363695] [<ffffffff8105fc9e>] ? kthread+0xce/0xf0
> [ 1080.363698] [<ffffffff81060000>] ? queue_kthread_work+0x80/0x80
> [ 1080.363702] [<ffffffff8105fbd0>] ? kthread_create_on_node+0x180/0x180
> [ 1080.363706] [<ffffffff8153ed2c>] ? ret_from_fork+0x7c/0xb0
> [ 1080.363709] [<ffffffff8105fbd0>] ? kthread_create_on_node+0x180/0x180

The get_state_synchronize_rcu() from within the wait for _rcu_barrier()
looks a bit odd, but perhaps this is stack-tracing inaccuracy.

Could you please send your .config?

Thanx, Paul