INFO: task kworker/0:2:4853 blocked for more than 120 seconds. Not tainted 4.16.0+ #4 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. kworker/0:2 D20616 4853 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: 00000000ffc3ff6b (rcu_read_lock){....}, at: check_hung_uninterruptible_tasks kernel/hung_task.c:175 [inline] #0: 00000000ffc3ff6b (rcu_read_lock){....}, at: watchdog+0x1ff/0xf60 kernel/hung_task.c:249 #1: 0000000022d5c4b1 (tasklist_lock){.+.+}, at: debug_show_all_locks+0xde/0x34a kernel/locking/lockdep.c:4470 2 locks held by rs:main Q:Reg/4371: #0: 00000000a7664156 (&f->f_pos_lock){+.+.}, at: __fdget_pos+0x1a9/0x1e0 fs/file.c:766 #1: 000000009ed56bf3 (sb_writers#4){.+.+}, at: file_start_write include/linux/fs.h:2710 [inline] #1: 000000009ed56bf3 (sb_writers#4){.+.+}, at: vfs_write+0x452/0x560 fs/read_write.c:548 2 locks held by getty/4463: #0: 00000000408e98c8 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 00000000bd10f518 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4464: #0: 000000000c5e26d2 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 00000000545eff78 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4465: #0: 00000000f3c7adbd (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 00000000002ccb4a (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4466: #0: 00000000c67202f7 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 000000006a60156c (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4467: #0: 0000000004f86450 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 000000006a98e99d (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4468: #0: 00000000ad72254b (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 00000000028a447b (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4469: #0: 00000000f4a46308 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 000000003b4f0236 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by kworker/0:2/4853: #0: 0000000025eeb26b ((wq_completion)"events"){+.+.}, at: __write_once_size include/linux/compiler.h:215 [inline] #0: 0000000025eeb26b ((wq_completion)"events"){+.+.}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline] #0: 0000000025eeb26b ((wq_completion)"events"){+.+.}, at: atomic64_set include/asm-generic/atomic-instrumented.h:40 [inline] #0: 0000000025eeb26b ((wq_completion)"events"){+.+.}, at: atomic_long_set include/asm-generic/atomic-long.h:57 [inline] #0: 0000000025eeb26b ((wq_completion)"events"){+.+.}, at: set_work_data kernel/workqueue.c:617 [inline] #0: 0000000025eeb26b ((wq_completion)"events"){+.+.}, at: set_work_pool_and_clear_pending kernel/workqueue.c:644 [inline] #0: 0000000025eeb26b ((wq_completion)"events"){+.+.}, at: process_one_work+0xaef/0x1b50 kernel/workqueue.c:2116 #1: 00000000a9c75e1a ((work_completion)(&wb->release_work)){+.+.}, at: process_one_work+0xb46/0x1b50 kernel/workqueue.c:2120 1 lock held by syz-executor5/7591: #0: 0000000040696eee (event_mutex){+.+.}, at: perf_trace_destroy+0x28/0x100 kernel/trace/trace_event_perf.c:235 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 882 Comm: khungtaskd Not tainted 4.16.0+ #4 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 binder: 7590:7599 ioctl c0306201 2001bfd0 returned -14 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 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 PID: 10440 Comm: kworker/0:3 Not tainted 4.16.0+ #4 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:get_current arch/x86/include/asm/current.h:15 [inline] RIP: 0010:__lock_acquire+0xa/0x5130 kernel/locking/lockdep.c:3291 RSP: 0018:ffff880197c87710 EFLAGS: 00000002 RAX: 0000000000000000 RBX: 1ffff10032f90eed RCX: 0000000000000000 RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff8801db02c4d8 RBP: ffff880197c87830 R08: 0000000000000001 R09: 0000000000000001 R10: ffffed003b6046c2 R11: ffff8801c9daa240 R12: ffff8801c9daa240 R13: 0000000000000000 R14: 0000000000000001 R15: 0000000000000000 FS: 0000000000000000(0000) GS:ffff8801db000000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000130 CR3: 000000019be58000 CR4: 00000000001406f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline] _raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:144 rq_lock kernel/sched/sched.h:1792 [inline] __schedule+0x246/0x1e40 kernel/sched/core.c:3428 schedule+0xef/0x430 kernel/sched/core.c:3549 worker_thread+0x412/0x1440 kernel/workqueue.c:2300 kthread+0x345/0x410 kernel/kthread.c:238 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:411 Code: ff ff e8 6a 6e 57 00 e9 e8 fe ff ff e8 60 6e 57 00 e9 48 ff ff ff 90 66 2e 0f 1f 84 00 00 00 00 00 55 65 4c 8b 1c 25 c0 ed 01 00 <48> 89 e5 41 57 49 89 ff 41 56 41 89 ce 41 55 41 89 d5 48 ba 00