I believe we are running into the same bug on 4.4.0-34-generic. Here is the output of dmesg when the issue starts. Let me know if I can provide any more info.
INFO: task kworker/1:1:20481 blocked for more than 120 seconds. Not tainted 4.4.0-34-generic #53~14.04.1-Ubuntu "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. kworker/1:1 D ffff88007a0b7ce8 0 20481 2 0x00000080 Workqueue: cifsiod cifs_oplock_break [cifs] ffff88007a0b7ce8 ffff8800791b3700 ffff880075408000 ffff88007a0b8000 0000000000000002 ffff88007a0b7d80 ffff88007ffcf960 ffffffff817f4210 ffff88007a0b7d00 ffffffff817f3b25 0000000000000002 ffff88007a0b7d18 Call Trace: [<ffffffff817f4210>] ? out_of_line_wait_on_atomic_t+0xd0/0xd0 [<ffffffff817f3b25>] schedule+0x35/0x80 [<ffffffff817f4221>] bit_wait+0x11/0x50 [<ffffffff817f3ec0>] __wait_on_bit+0x60/0x90 [<ffffffff817f4210>] ? out_of_line_wait_on_atomic_t+0xd0/0xd0 [<ffffffff817f3f62>] out_of_line_wait_on_bit+0x72/0x80 [<ffffffff810bdca0>] ? autoremove_wake_function+0x40/0x40 [<ffffffffc02bf5eb>] cifs_oplock_break+0x6b/0x3a0 [cifs] [<ffffffff81095970>] process_one_work+0x150/0x3f0 [<ffffffff810960ea>] worker_thread+0x11a/0x470 [<ffffffff817f34c9>] ? __schedule+0x359/0x980 [<ffffffff81095fd0>] ? rescuer_thread+0x310/0x310 [<ffffffff8109b849>] kthread+0xc9/0xe0 [<ffffffff8109b780>] ? kthread_park+0x60/0x60 [<ffffffff817f770f>] ret_from_fork+0x3f/0x70 [<ffffffff8109b780>] ? kthread_park+0x60/0x60
I believe we are running into the same bug on 4.4.0-34-generic. Here is the output of dmesg when the issue starts. Let me know if I can provide any more info.
INFO: task kworker/1:1:20481 blocked for more than 120 seconds. kernel/ hung_task_ timeout_ secs" disables this message. 4210>] ? out_of_ line_wait_ on_atomic_ t+0xd0/ 0xd0 3b25>] schedule+0x35/0x80 4221>] bit_wait+0x11/0x50 3ec0>] __wait_ on_bit+ 0x60/0x90 4210>] ? out_of_ line_wait_ on_atomic_ t+0xd0/ 0xd0 3f62>] out_of_ line_wait_ on_bit+ 0x72/0x80 dca0>] ? autoremove_ wake_function+ 0x40/0x40 f5eb>] cifs_oplock_ break+0x6b/ 0x3a0 [cifs] 5970>] process_ one_work+ 0x150/0x3f0 60ea>] worker_ thread+ 0x11a/0x470 34c9>] ? __schedule+ 0x359/0x980 5fd0>] ? rescuer_ thread+ 0x310/0x310 b849>] kthread+0xc9/0xe0 b780>] ? kthread_ park+0x60/ 0x60 770f>] ret_from_ fork+0x3f/ 0x70 b780>] ? kthread_ park+0x60/ 0x60
Not tainted 4.4.0-34-generic #53~14.04.1-Ubuntu
"echo 0 > /proc/sys/
kworker/1:1 D ffff88007a0b7ce8 0 20481 2 0x00000080
Workqueue: cifsiod cifs_oplock_break [cifs]
ffff88007a0b7ce8 ffff8800791b3700 ffff880075408000 ffff88007a0b8000
0000000000000002 ffff88007a0b7d80 ffff88007ffcf960 ffffffff817f4210
ffff88007a0b7d00 ffffffff817f3b25 0000000000000002 ffff88007a0b7d18
Call Trace:
[<ffffffff817f
[<ffffffff817f
[<ffffffff817f
[<ffffffff817f
[<ffffffff817f
[<ffffffff817f
[<ffffffff810b
[<ffffffffc02b
[<ffffffff8109
[<ffffffff8109
[<ffffffff817f
[<ffffffff8109
[<ffffffff8109
[<ffffffff8109
[<ffffffff817f
[<ffffffff8109