INFO: task kworker/0:3:4967 blocked for more than 120 seconds. Not tainted 4.17.0-rc1+ #12 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. kworker/0:3 D23144 4967 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/893: #0: (ptrval) (rcu_read_lock){....}, at: check_hung_uninterruptible_tasks kernel/hung_task.c:175 [inline] #0: (ptrval) (rcu_read_lock){....}, at: watchdog+0x1ff/0xf60 kernel/hung_task.c:249 #1: (ptrval) (tasklist_lock){.+.+}, at: debug_show_all_locks+0xde/0x34a kernel/locking/lockdep.c:4470 2 locks held by getty/4493: #0: (ptrval) (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (ptrval) (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4494: #0: (ptrval) (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (ptrval) (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4495: #0: (ptrval) (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (ptrval) (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4496: #0: (ptrval) (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (ptrval) (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4497: #0: (ptrval) (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (ptrval) (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4498: #0: (ptrval) (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (ptrval) (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by kworker/0:3/4967: #0: (ptrval) ((wq_completion)"events"){+.+.}, at: __write_once_size include/linux/compiler.h:215 [inline] #0: (ptrval) ((wq_completion)"events"){+.+.}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline] #0: (ptrval) ((wq_completion)"events"){+.+.}, at: atomic64_set include/asm-generic/atomic-instrumented.h:40 [inline] #0: (ptrval) ((wq_completion)"events"){+.+.}, at: atomic_long_set include/asm-generic/atomic-long.h:57 [inline] #0: (ptrval) ((wq_completion)"events"){+.+.}, at: set_work_data kernel/workqueue.c:617 [inline] #0: (ptrval) ((wq_completion)"events"){+.+.}, at: set_work_pool_and_clear_pending kernel/workqueue.c:644 [inline] #0: (ptrval) ((wq_completion)"events"){+.+.}, at: process_one_work+0xaef/0x1b50 kernel/workqueue.c:2116 #1: (ptrval) ((work_completion)(&wb->release_work)){+.+.}, at: process_one_work+0xb46/0x1b50 kernel/workqueue.c:2120 2 locks held by getty/26773: #0: (ptrval) (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (ptrval) (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 1 lock held by syz-executor3/546: #0: (ptrval) (event_mutex){+.+.}, at: perf_trace_destroy+0x28/0x100 kernel/trace/trace_event_perf.c:235 2 locks held by syz-executor2/549: #0: (ptrval) (br_ioctl_mutex){+.+.}, at: sock_ioctl+0x2b5/0x680 net/socket.c:1046 #1: (ptrval) (rtnl_mutex){+.+.}, at: rtnl_lock+0x17/0x20 net/core/rtnetlink.c:74 1 lock held by syz-executor6/563: #0: (ptrval) (rtnl_mutex){+.+.}, at: rtnl_lock net/core/rtnetlink.c:74 [inline] #0: (ptrval) (rtnl_mutex){+.+.}, at: rtnetlink_rcv_msg+0x40a/0xc10 net/core/rtnetlink.c:4643 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 893 Comm: khungtaskd Not tainted 4.17.0-rc1+ #12 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: 4576 Comm: syz-executor7 Not tainted 4.17.0-rc1+ #12 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:rb_erase_cached+0x773/0x32a0 lib/rbtree.c:475 RSP: 0018:ffff8801919dec40 EFLAGS: 00000002 RAX: 0000000000000000 RBX: ffff8801b1f1b018 RCX: 0000000000000000 RDX: ffff8801919df618 RSI: ffff8801dae2c670 RDI: ffffed003233bec0 RBP: ffff8801919df640 R08: 1ffff100363e3605 R09: 0000000000000001 R10: 00000000000000aa R11: 0000000000000001 R12: ffffffffffffffff R13: ffff8801b1f1b018 R14: 0000000000000000 R15: 1ffff1003233be1b FS: 000000000231b940(0000) GS:ffff8801dae00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000002324978 CR3: 000000019192c000 CR4: 00000000001406f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: __dequeue_entity kernel/sched/fair.c:567 [inline] set_next_entity+0x2d6/0xaf0 kernel/sched/fair.c:4356 pick_next_task_fair+0xf26/0x1660 kernel/sched/fair.c:6999 pick_next_task kernel/sched/core.c:3336 [inline] __schedule+0x491/0x1e30 kernel/sched/core.c:3464 schedule+0xef/0x430 kernel/sched/core.c:3549 exit_to_usermode_loop+0x220/0x310 arch/x86/entry/common.c:152 prepare_exit_to_usermode arch/x86/entry/common.c:196 [inline] syscall_return_slowpath arch/x86/entry/common.c:265 [inline] do_syscall_64+0x6ac/0x800 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x457eb7 RSP: 002b:0000000000a3eab8 EFLAGS: 00000202 ORIG_RAX: 0000000000000029 RAX: 0000000000000013 RBX: 00000000000002bd RCX: 0000000000457eb7 RDX: 0000000000000006 RSI: 0000000000000001 RDI: 0000000000000002 RBP: 0000000000078641 R08: 0000000000000000 R09: 0000000000000001 R10: 0000000000000006 R11: 0000000000000202 R12: 0000000000000898 R13: 0000000000000002 R14: 0000000000000898 R15: 0000000000078622 Code: 24 08 49 c7 04 24 00 00 00 00 49 c7 84 24 2c 01 00 00 00 00 00 00 48 83 e7 f8 49 29 fc 41 8d 8c 24 34 01 00 00 c1 e9 03 f3 48 ab <48> 81 c4 d8 09 00 00 5b 41 5c 41 5d 41 5e 41 5f 5d c3 4d 89 ee INFO: NMI handler (nmi_cpu_backtrace_handler) took too long to run: 1.216 msecs