INFO: task kworker/0:2:1963 blocked for more than 120 seconds.
      Not tainted 4.16.0+ #2
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
kworker/0:2     D18952  1963      2 0x80000000
Workqueue: events cgwb_release_workfn
Call Trace:
 context_switch kernel/sched/core.c:2848 [inline]
 __schedule+0x807/0x1e40 kernel/sched/core.c:3490
 schedule+0xef/0x430 kernel/sched/core.c:3549
 bit_wait+0x18/0x90 kernel/sched/wait_bit.c:197
 __wait_on_bit+0xb3/0x130 kernel/sched/wait_bit.c:48
 out_of_line_wait_on_bit+0x204/0x3a0 kernel/sched/wait_bit.c:63
 wait_on_bit include/linux/wait_bit.h:76 [inline]
 wb_shutdown+0x370/0x470 mm/backing-dev.c:377
 cgwb_release_workfn+0x87/0x750 mm/backing-dev.c:520
 process_one_work+0xc1e/0x1b50 kernel/workqueue.c:2145
 worker_thread+0x1cc/0x1440 kernel/workqueue.c:2279
 kthread+0x345/0x410 kernel/kthread.c:238
 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:411

Showing all locks held in the system:
2 locks held by khungtaskd/879:
 #0: 00000000fc302a3b (rcu_read_lock){....}, at: check_hung_uninterruptible_tasks kernel/hung_task.c:175 [inline]
 #0: 00000000fc302a3b (rcu_read_lock){....}, at: watchdog+0x1ff/0xf60 kernel/hung_task.c:249
 #1: 0000000088580f6f (tasklist_lock){.+.+}, at: debug_show_all_locks+0xde/0x34a kernel/locking/lockdep.c:4470
2 locks held by kworker/0:2/1963:
 #0: 00000000241204db ((wq_completion)"events"){+.+.}, at: __write_once_size include/linux/compiler.h:215 [inline]
 #0: 00000000241204db ((wq_completion)"events"){+.+.}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
 #0: 00000000241204db ((wq_completion)"events"){+.+.}, at: atomic64_set include/asm-generic/atomic-instrumented.h:40 [inline]
 #0: 00000000241204db ((wq_completion)"events"){+.+.}, at: atomic_long_set include/asm-generic/atomic-long.h:57 [inline]
 #0: 00000000241204db ((wq_completion)"events"){+.+.}, at: set_work_data kernel/workqueue.c:617 [inline]
 #0: 00000000241204db ((wq_completion)"events"){+.+.}, at: set_work_pool_and_clear_pending kernel/workqueue.c:644 [inline]
 #0: 00000000241204db ((wq_completion)"events"){+.+.}, at: process_one_work+0xaef/0x1b50 kernel/workqueue.c:2116
 #1: 000000009203cab2 ((work_completion)(&wb->release_work)){+.+.}, at: process_one_work+0xb46/0x1b50 kernel/workqueue.c:2120
1 lock held by rsyslogd/4343:
 #0: 000000001c74cc15 (&f->f_pos_lock){+.+.}, at: __fdget_pos+0x1a9/0x1e0 fs/file.c:766
2 locks held by getty/4433:
 #0: 00000000abddba98 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365
 #1: 00000000e1296fe4 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131
2 locks held by getty/4434:
 #0: 00000000a6ed9997 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365
 #1: 00000000a5148434 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131
2 locks held by getty/4435:
 #0: 00000000637eeedb (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365
 #1: 0000000059a4e396 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131
2 locks held by getty/4436:
 #0: 00000000b650ceec (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365
 #1: 000000002a123edc (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131
2 locks held by getty/4437:
 #0: 0000000052d11329 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365
 #1: 000000000bd73a02 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131
2 locks held by getty/4438:
 #0: 00000000b3eb42cd (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365
 #1: 000000007260abee (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131
2 locks held by getty/4439:
 #0: 00000000b4d3def3 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365
 #1: 000000005908c37e (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131
3 locks held by syz-executor0/25263:
 #0: 00000000c3ab0d5f (&sig->cred_guard_mutex){+.+.}, at: SYSC_perf_event_open+0x129f/0x2fa0 kernel/events/core.c:10457
 #1: 000000003147e0a4 (&pmus_srcu){....}, at: perf_event_alloc.part.91+0x103c/0x30a0 kernel/events/core.c:10018
 #2: 00000000049f7165 (event_mutex){+.+.}, at: perf_trace_init+0x50/0x250 kernel/trace/trace_event_perf.c:217
3 locks held by syz-executor5/25262:
 #0: 000000000ffd2edf (&sig->cred_guard_mutex){+.+.}, at: SYSC_perf_event_open+0x129f/0x2fa0 kernel/events/core.c:10457
 #1: 000000003147e0a4 (&pmus_srcu){....}, at: perf_event_alloc.part.91+0x103c/0x30a0 kernel/events/core.c:10018
 #2: 00000000049f7165 (event_mutex){+.+.}, at: perf_trace_init+0x50/0x250 kernel/trace/trace_event_perf.c:217
1 lock held by syz-executor2/25250:
 #0: 00000000049f7165 (event_mutex){+.+.}, at: perf_trace_destroy+0x28/0x100 kernel/trace/trace_event_perf.c:235
3 locks held by syz-executor4/25253:
 #0: 000000007292fe67 (&sig->cred_guard_mutex){+.+.}, at: SYSC_perf_event_open+0x129f/0x2fa0 kernel/events/core.c:10457
 #1: 000000003147e0a4 (&pmus_srcu){....}, at: perf_event_alloc.part.91+0x103c/0x30a0 kernel/events/core.c:10018
 #2: 00000000049f7165 (event_mutex){+.+.}, at: perf_trace_init+0x50/0x250 kernel/trace/trace_event_perf.c:217
1 lock held by syz-executor1/25264:
 #0: 00000000049f7165 (event_mutex){+.+.}, at: perf_trace_destroy+0x28/0x100 kernel/trace/trace_event_perf.c:235

=============================================

NMI backtrace for cpu 0
CPU: 0 PID: 879 Comm: khungtaskd Not tainted 4.16.0+ #2
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0x1b9/0x29f lib/dump_stack.c:53
 nmi_cpu_backtrace.cold.4+0x19/0xce lib/nmi_backtrace.c:103
 nmi_trigger_cpumask_backtrace+0x151/0x192 lib/nmi_backtrace.c:62
 arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:38
 trigger_all_cpu_backtrace include/linux/nmi.h:138 [inline]
 check_hung_task kernel/hung_task.c:132 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:190 [inline]
 watchdog+0xc10/0xf60 kernel/hung_task.c:249
 kthread+0x345/0x410 kernel/kthread.c:238
 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:411
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 25246 Comm: syz-executor0 Not tainted 4.16.0+ #2
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:debug_lockdep_rcu_enabled+0x37/0x90 kernel/rcu/update.c:300
RSP: 0018:ffff8801db107290 EFLAGS: 00000046
RAX: 0000000000000003 RBX: ffff8801db11f560 RCX: 0000000000000000
RDX: 0000000000000002 RSI: ffffffff88b8c7a0 RDI: ffffffff89571b40
RBP: ffff8801db107290 R08: ffffed003b6246c3 R09: ffffed003b6246c2
R10: ffffed003b6246c2 R11: ffff8801db123613 R12: 1ffff1003b620e8c
R13: 0000000000000001 R14: 0000000000000001 R15: ffff8801db11f4d0
FS:  00000000015a3940(0000) GS:ffff8801db100000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020223000 CR3: 00000001d6baa000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <IRQ>
 select_idle_cpu kernel/sched/fair.c:6377 [inline]
 select_idle_sibling+0x6ba/0xd80 kernel/sched/fair.c:6458
 select_task_rq_fair+0x2142/0x3820 kernel/sched/fair.c:6669
 select_task_rq kernel/sched/core.c:1528 [inline]
 try_to_wake_up+0x4ce/0x11a0 kernel/sched/core.c:2038
 wake_up_process+0x10/0x20 kernel/sched/core.c:2126
 hrtimer_wakeup+0x48/0x60 kernel/time/hrtimer.c:1586
 __run_hrtimer kernel/time/hrtimer.c:1337 [inline]
 __hrtimer_run_queues+0x3e3/0x10a0 kernel/time/hrtimer.c:1399
 hrtimer_interrupt+0x286/0x650 kernel/time/hrtimer.c:1457
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1025 [inline]
 smp_apic_timer_interrupt+0x15d/0x710 arch/x86/kernel/apic/apic.c:1050
 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:862
 </IRQ>
RIP: 0010:write_comp_data+0x1/0x70 kernel/kcov.c:116
RSP: 0018:ffff8801aaa1fc78 EFLAGS: 00000293 ORIG_RAX: ffffffffffffff13
RAX: ffff8801b0afe340 RBX: 0000000000000010 RCX: ffffffff8331c7ce
RDX: 00007ffffffff000 RSI: 0000000000a3e960 RDI: 0000000000000006
RBP: ffff8801aaa1fc88 R08: ffff8801b0afe340 R09: ffff8801aaa1f9b8
R10: 0000000000000003 R11: 0000000000000000 R12: 0000000000a3e960
R13: 0000000000a3e950 R14: ffff8801aaa1fd00 R15: 00007ffffffff000
 _copy_to_user+0xbe/0x110 lib/usercopy.c:26
 copy_to_user include/linux/uaccess.h:155 [inline]
 put_timespec64+0xf2/0x1a0 kernel/time/time.c:879
 SYSC_clock_gettime kernel/time/posix-timers.c:1070 [inline]
 SyS_clock_gettime+0x168/0x1f0 kernel/time/posix-timers.c:1058
 do_syscall_64+0x29e/0x9d0 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x4580fa
RSP: 002b:0000000000a3e948 EFLAGS: 00000246 ORIG_RAX: 00000000000000e4
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00000000004580fa
RDX: 000000000072ca20 RSI: 0000000000a3e950 RDI: 0000000000000001
RBP: 0000000000000001 R08: 0000000000a3f7af R09: 0000000000000000
R10: 0000000000a3e940 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000002 R14: 000000000072ca20 R15: 000000000005a764
Code: 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 0f b6 14 02 48 89 f8 48 89 e5 83 e0 07 83 c0 03 38 d0 7c 04 84 d2 75 4c 8b 15 69 57 f5 07 <85> d2 74 3e 48 c7 c7 20 a5 e6 88 48 b8 00 00 00 00 00 fc ff df