INFO: task kworker/1:2:2081 blocked for more than 120 seconds. Not tainted 4.16.0+ #3 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. kworker/1:2 D20760 2081 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/882: #0: 000000005330ff91 (rcu_read_lock){....}, at: check_hung_uninterruptible_tasks kernel/hung_task.c:175 [inline] #0: 000000005330ff91 (rcu_read_lock){....}, at: watchdog+0x1ff/0xf60 kernel/hung_task.c:249 #1: 00000000ae0f41bb (tasklist_lock){.+.+}, at: debug_show_all_locks+0xde/0x34a kernel/locking/lockdep.c:4470 2 locks held by kworker/1:2/2081: #0: 000000004f4eb4bb ((wq_completion)"events"){+.+.}, at: __write_once_size include/linux/compiler.h:215 [inline] #0: 000000004f4eb4bb ((wq_completion)"events"){+.+.}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline] #0: 000000004f4eb4bb ((wq_completion)"events"){+.+.}, at: atomic64_set include/asm-generic/atomic-instrumented.h:40 [inline] #0: 000000004f4eb4bb ((wq_completion)"events"){+.+.}, at: atomic_long_set include/asm-generic/atomic-long.h:57 [inline] #0: 000000004f4eb4bb ((wq_completion)"events"){+.+.}, at: set_work_data kernel/workqueue.c:617 [inline] #0: 000000004f4eb4bb ((wq_completion)"events"){+.+.}, at: set_work_pool_and_clear_pending kernel/workqueue.c:644 [inline] #0: 000000004f4eb4bb ((wq_completion)"events"){+.+.}, at: process_one_work+0xaef/0x1b50 kernel/workqueue.c:2116 #1: 000000003c7b88b6 ((work_completion)(&wb->release_work)){+.+.}, at: process_one_work+0xb46/0x1b50 kernel/workqueue.c:2120 2 locks held by getty/4323: #0: 00000000da34d9ce (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 00000000cdab3cdc (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4324: #0: 00000000b091e256 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 00000000e26b09dd (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4325: #0: 00000000c39dc91a (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 000000006f2b346b (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4326: #0: 0000000013238ebc (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 00000000ecac637a (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4327: #0: 00000000f3c1be39 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 00000000e3615d09 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4328: #0: 00000000bca6325e (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 00000000affa7f4b (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4329: #0: 000000005e182940 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 00000000ef3131e1 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 882 Comm: khungtaskd Not tainted 4.16.0+ #3 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x1b9/0x294 lib/dump_stack.c:113 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: 25594 Comm: syz-executor1 Not tainted 4.16.0+ #3 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:match_held_lock+0x2f2/0x8b0 kernel/locking/lockdep.c:3491 RSP: 0018:ffff8801a0776638 EFLAGS: 00000086 RAX: 0000000000000000 RBX: ffff8801ca732f60 RCX: 0000000000000000 RDX: ffffed00340eeccc RSI: ffffffff88b8c620 RDI: ffff8801ca732f82 RBP: ffff8801a0776728 R08: ffffed003b6246c3 R09: ffffed003b6246c2 R10: ffffed003b6246c2 R11: ffff8801db123613 R12: 1ffff100340eeccc R13: ffff8801ca732f60 R14: ffff8801a0776700 R15: 0000000000000001 FS: 00007fba06188700(0000) GS:ffff8801db100000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fe87d920000 CR3: 00000001a50b2000 CR4: 00000000001426e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: __lock_is_held+0xb5/0x140 kernel/locking/lockdep.c:3740 lock_is_held_type+0x121/0x210 kernel/locking/lockdep.c:3958 lock_is_held include/linux/lockdep.h:344 [inline] rcu_read_lock_sched_held+0x108/0x120 kernel/rcu/update.c:117 trace_sched_switch include/trace/events/sched.h:128 [inline] __schedule+0x14f6/0x1e40 kernel/sched/core.c:3487 preempt_schedule_common+0x22/0x60 kernel/sched/core.c:3629 _cond_resched+0x1d/0x30 kernel/sched/core.c:4978 __mutex_lock_common kernel/locking/mutex.c:747 [inline] __mutex_lock+0x142/0x17f0 kernel/locking/mutex.c:893 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908 arch_jump_label_transform+0x1b/0x40 arch/x86/kernel/jump_label.c:109 __jump_label_update+0x16e/0x1a0 kernel/jump_label.c:375 jump_label_update+0x151/0x2e0 kernel/jump_label.c:760 __static_key_slow_dec_cpuslocked+0xb0/0x200 kernel/jump_label.c:205 __static_key_slow_dec kernel/jump_label.c:215 [inline] static_key_slow_dec+0x63/0xa0 kernel/jump_label.c:229 preempt_notifier_dec+0x10/0x20 kernel/sched/core.c:2475 kvm_destroy_vm arch/x86/kvm/../../../virt/kvm/kvm_main.c:736 [inline] kvm_put_kvm+0xa32/0xfd0 arch/x86/kvm/../../../virt/kvm/kvm_main.c:750 kvm_vm_release+0x42/0x50 arch/x86/kvm/../../../virt/kvm/kvm_main.c:761 __fput+0x34d/0x890 fs/file_table.c:209 ____fput+0x15/0x20 fs/file_table.c:243 task_work_run+0x1e4/0x290 kernel/task_work.c:113 exit_task_work include/linux/task_work.h:22 [inline] do_exit+0x1aee/0x2730 kernel/exit.c:865 do_group_exit+0x16f/0x430 kernel/exit.c:968 get_signal+0x886/0x1960 kernel/signal.c:2469 do_signal+0x98/0x2040 arch/x86/kernel/signal.c:810 exit_to_usermode_loop+0x28a/0x310 arch/x86/entry/common.c:162 prepare_exit_to_usermode arch/x86/entry/common.c:196 [inline] syscall_return_slowpath arch/x86/entry/common.c:265 [inline] do_syscall_64+0x792/0x9d0 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x42/0xb7 RIP: 0033:0x4552d9 RSP: 002b:00007fba06187ce8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca RAX: fffffffffffffe00 RBX: 000000000072c038 RCX: 00000000004552d9 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 000000000072c038 RBP: 000000000072c038 R08: 0000000000000000 R09: 000000000072c010 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000a3e81f R14: 00007fba061889c0 R15: 0000000000000002 Code: f8 4d 85 ff 75 3e 31 c0 48 ba 00 00 00 00 00 fc ff df 4c 01 e2 48 c7 02 00 00 00 00 48 c7 42 08 00 00 00 00 c7 42 10 00 00 00 00 <48> 81 c4 c8 00 00 00 5b 41 5c 41 5d 41 5e 41 5f 5d c3 b8 01 00 INFO: NMI handler (nmi_cpu_backtrace_handler) took too long to run: 1.463 msecs