INFO: task kworker/1:2:4874 blocked for more than 120 seconds. Not tainted 4.17.0-rc2+ #19 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. kworker/1:2 D18648 4874 2 0x80000000 Workqueue: events cgwb_release_workfn Call Trace: context_switch kernel/sched/core.c:2848 [inline] __schedule+0x801/0x1e30 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:366 cgwb_release_workfn+0x87/0x750 mm/backing-dev.c:509 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:412 Showing all locks held in the system: 2 locks held by khungtaskd/892: #0: 00000000c57f32c7 (rcu_read_lock){....}, at: check_hung_uninterruptible_tasks kernel/hung_task.c:175 [inline] #0: 00000000c57f32c7 (rcu_read_lock){....}, at: watchdog+0x1ff/0xf60 kernel/hung_task.c:249 #1: 0000000079ffbb13 (tasklist_lock){.+.+}, at: debug_show_all_locks+0xde/0x34a kernel/locking/lockdep.c:4470 2 locks held by getty/4513: #0: 000000009e048130 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 00000000a20de475 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4514: #0: 00000000ddcfc7ea (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 00000000fd186e49 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4515: #0: 00000000b5c987b9 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 0000000041a3bef9 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4516: #0: 000000000f5c9d24 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 00000000f525d180 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4517: #0: 000000009eb64607 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 00000000fafaffb8 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4518: #0: 00000000c6abb739 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 00000000afad6ae1 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4519: #0: 00000000044fd8fc (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 00000000e8ea0450 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by kworker/1:2/4874: #0: 00000000c3081077 ((wq_completion)"events"){+.+.}, at: __write_once_size include/linux/compiler.h:215 [inline] #0: 00000000c3081077 ((wq_completion)"events"){+.+.}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline] #0: 00000000c3081077 ((wq_completion)"events"){+.+.}, at: atomic64_set include/asm-generic/atomic-instrumented.h:40 [inline] #0: 00000000c3081077 ((wq_completion)"events"){+.+.}, at: atomic_long_set include/asm-generic/atomic-long.h:57 [inline] #0: 00000000c3081077 ((wq_completion)"events"){+.+.}, at: set_work_data kernel/workqueue.c:617 [inline] #0: 00000000c3081077 ((wq_completion)"events"){+.+.}, at: set_work_pool_and_clear_pending kernel/workqueue.c:644 [inline] #0: 00000000c3081077 ((wq_completion)"events"){+.+.}, at: process_one_work+0xaef/0x1b50 kernel/workqueue.c:2116 #1: 0000000004b5af84 ((work_completion)(&wb->release_work)){+.+.}, at: process_one_work+0xb46/0x1b50 kernel/workqueue.c:2120 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 892 Comm: khungtaskd Not tainted 4.17.0-rc2+ #19 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:412 Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 PID: 726 Comm: syz-executor3 Not tainted 4.17.0-rc2+ #19 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:__read_once_size include/linux/compiler.h:188 [inline] RIP: 0010:lookup_chain_cache kernel/locking/lockdep.c:2314 [inline] RIP: 0010:lookup_chain_cache_add kernel/locking/lockdep.c:2334 [inline] RIP: 0010:validate_chain kernel/locking/lockdep.c:2388 [inline] RIP: 0010:__lock_acquire+0xe7c/0x5140 kernel/locking/lockdep.c:3431 RSP: 0018:ffff8801dae07920 EFLAGS: 00000046 RAX: dffffc0000000000 RBX: ffffffff89c3c688 RCX: 0000000073e4b59a RDX: 1ffffffff143fa6d RSI: ffff880199db0c38 RDI: ffff880199db0d71 RBP: ffff8801dae07ca8 R08: 0000000000002b6d R09: 0000000000000007 R10: ffff880199db0d50 R11: ffff880199db0400 R12: ffff8801dae07a60 R13: 0000000000000040 R14: b39d2cf2ee574af9 R15: 0000000000000001 FS: 00007f48057d2700(0000) GS:ffff8801dae00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00000000004ccae0 CR3: 00000001d6e2b000 CR4: 00000000001426f0 DR0: 0000000020000000 DR1: 0000000020000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: lock_acquire+0x1dc/0x520 kernel/locking/lockdep.c:3920 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0x96/0xc0 kernel/locking/spinlock.c:152 hrtimer_interrupt+0xd2/0x650 kernel/time/hrtimer.c:1487 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:863 RIP: 0010:__sanitizer_cov_trace_pc+0x3f/0x50 kernel/kcov.c:106 RSP: 0018:ffff8801995c6db0 EFLAGS: 00000202 ORIG_RAX: ffffffffffffff13 RAX: 0000000000040000 RBX: ffff8801995c6eb8 RCX: ffffc900052ab000 RDX: 000000000000515d RSI: ffffffff816d242e RDI: 0000000000000005 RBP: ffff8801995c6db0 R08: ffff880199db0400 R09: ffffed003b5e5aa8 R10: ffffed003b5e5aa8 R11: ffff8801daf2d547 R12: ffffed00332b8dcc R13: dffffc0000000000 R14: 0000000000000000 R15: 0000000000000001 rep_nop arch/x86/include/asm/processor.h:667 [inline] cpu_relax arch/x86/include/asm/processor.h:672 [inline] csd_lock_wait kernel/smp.c:108 [inline] smp_call_function_single+0x3de/0x5b0 kernel/smp.c:302 smp_call_function_many+0x870/0xa20 kernel/smp.c:434 smp_call_function kernel/smp.c:492 [inline] on_each_cpu+0x46/0x1d0 kernel/smp.c:602 text_poke_bp+0x105/0x158 arch/x86/kernel/alternative.c:814 __jump_label_transform.isra.0+0x43c/0x890 arch/x86/kernel/jump_label.c:102 arch_jump_label_transform+0x2f/0x40 arch/x86/kernel/jump_label.c:110 __jump_label_update+0x16e/0x1a0 kernel/jump_label.c:375 jump_label_update+0x151/0x2e0 kernel/jump_label.c:760 static_key_slow_inc_cpuslocked+0x32d/0x420 kernel/jump_label.c:110 static_key_slow_inc+0x1a/0x30 kernel/jump_label.c:125 tracepoint_add_func kernel/tracepoint.c:222 [inline] tracepoint_probe_register_prio+0x8d8/0xa40 kernel/tracepoint.c:282 tracepoint_probe_register+0x2a/0x40 kernel/tracepoint.c:303 trace_event_reg+0x19a/0x350 kernel/trace/trace_events.c:305 perf_trace_event_reg kernel/trace/trace_event_perf.c:123 [inline] perf_trace_event_init+0x4fe/0x990 kernel/trace/trace_event_perf.c:198 perf_trace_init+0x186/0x250 kernel/trace/trace_event_perf.c:222 perf_tp_event_init+0xa6/0x120 kernel/events/core.c:8337 perf_try_init_event+0x137/0x2f0 kernel/events/core.c:9734 perf_init_event kernel/events/core.c:9772 [inline] perf_event_alloc.part.91+0x1248/0x3090 kernel/events/core.c:10038 perf_event_alloc kernel/events/core.c:10394 [inline] __do_sys_perf_event_open+0xa8a/0x2fa0 kernel/events/core.c:10495 __se_sys_perf_event_open kernel/events/core.c:10384 [inline] __x64_sys_perf_event_open+0xbe/0x150 kernel/events/core.c:10384 do_syscall_64+0x1b1/0x800 arch/x86/entry/common.c:287 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x455389 RSP: 002b:00007f48057d1c68 EFLAGS: 00000246 ORIG_RAX: 000000000000012a RAX: ffffffffffffffda RBX: 00007f48057d26d4 RCX: 0000000000455389 RDX: ffffffffffffffff RSI: 0000000000000000 RDI: 000000002025c000 RBP: 000000000072bea0 R08: 0000000000000000 R09: 0000000000000000 R10: ffffffffffffffff R11: 0000000000000246 R12: 00000000ffffffff R13: 0000000000000462 R14: 00000000006f99d0 R15: 0000000000000000 Code: 44 24 70 48 b8 00 00 00 00 00 fc ff df 48 c1 ea 03 80 3c 02 00 0f 85 b6 33 00 00 4c 8d a4 24 40 01 00 00 4a 8b 1c c5 00 78 1e 8a <48> b8 00 00 00 00 00 fc ff df 4c 89 e2 48 c1 ea 03 80 3c 02 00