INFO: task kworker/0:2:4799 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 D19128 4799 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:411 Showing all locks held in the system: 2 locks held by kworker/0:1/24: #0: 00000000c818b325 ((wq_completion)"rcu_gp"){+.+.}, at: __write_once_size include/linux/compiler.h:215 [inline] #0: 00000000c818b325 ((wq_completion)"rcu_gp"){+.+.}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline] #0: 00000000c818b325 ((wq_completion)"rcu_gp"){+.+.}, at: atomic64_set include/asm-generic/atomic-instrumented.h:40 [inline] #0: 00000000c818b325 ((wq_completion)"rcu_gp"){+.+.}, at: atomic_long_set include/asm-generic/atomic-long.h:57 [inline] #0: 00000000c818b325 ((wq_completion)"rcu_gp"){+.+.}, at: set_work_data kernel/workqueue.c:617 [inline] #0: 00000000c818b325 ((wq_completion)"rcu_gp"){+.+.}, at: set_work_pool_and_clear_pending kernel/workqueue.c:644 [inline] #0: 00000000c818b325 ((wq_completion)"rcu_gp"){+.+.}, at: process_one_work+0xaef/0x1b50 kernel/workqueue.c:2116 #1: 00000000b9845200 ((work_completion)(&rew.rew_work)){+.+.}, at: process_one_work+0xb46/0x1b50 kernel/workqueue.c:2120 2 locks held by khungtaskd/889: #0: 00000000e9b8067f (rcu_read_lock){....}, at: check_hung_uninterruptible_tasks kernel/hung_task.c:175 [inline] #0: 00000000e9b8067f (rcu_read_lock){....}, at: watchdog+0x1ff/0xf60 kernel/hung_task.c:249 #1: 00000000e4358816 (tasklist_lock){.+.+}, at: debug_show_all_locks+0xde/0x34a kernel/locking/lockdep.c:4470 2 locks held by getty/4444: #0: 00000000c127031c (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 00000000c11af030 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4445: #0: 0000000054ab3824 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 00000000355ac398 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4446: #0: 000000004a214ce7 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 00000000a0780646 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4447: #0: 00000000035af017 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 0000000019717126 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4448: #0: 00000000e87d85ed (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 000000000cb15ad7 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4449: #0: 000000006ca0aa7d (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 000000004e5bae17 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4450: #0: 00000000df441fa4 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 00000000e6015d18 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by kworker/0:2/4799: #0: 000000001441c380 ((wq_completion)"events"){+.+.}, at: __write_once_size include/linux/compiler.h:215 [inline] #0: 000000001441c380 ((wq_completion)"events"){+.+.}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline] #0: 000000001441c380 ((wq_completion)"events"){+.+.}, at: atomic64_set include/asm-generic/atomic-instrumented.h:40 [inline] #0: 000000001441c380 ((wq_completion)"events"){+.+.}, at: atomic_long_set include/asm-generic/atomic-long.h:57 [inline] #0: 000000001441c380 ((wq_completion)"events"){+.+.}, at: set_work_data kernel/workqueue.c:617 [inline] #0: 000000001441c380 ((wq_completion)"events"){+.+.}, at: set_work_pool_and_clear_pending kernel/workqueue.c:644 [inline] #0: 000000001441c380 ((wq_completion)"events"){+.+.}, at: process_one_work+0xaef/0x1b50 kernel/workqueue.c:2116 #1: 00000000e5f9ee62 ((work_completion)(&wb->release_work)){+.+.}, at: process_one_work+0xb46/0x1b50 kernel/workqueue.c:2120 2 locks held by syz-executor0/19187: #0: 000000005e83112e (rtnl_mutex){+.+.}, at: rtnl_lock+0x17/0x20 net/core/rtnetlink.c:74 #1: 00000000d5c0b857 (rcu_sched_state.exp_mutex){+.+.}, at: exp_funnel_lock kernel/rcu/tree_exp.h:281 [inline] #1: 00000000d5c0b857 (rcu_sched_state.exp_mutex){+.+.}, at: _synchronize_rcu_expedited.constprop.73+0x9dd/0xad0 kernel/rcu/tree_exp.h:616 4 locks held by syz-executor7/19195: #0: 000000007697bcef (cb_lock){++++}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:634 #1: 00000000daac81e1 (nlk_cb_mutex-GENERIC){+.+.}, at: netlink_dump+0x98/0xd20 net/netlink/af_netlink.c:2182 #2: 0000000000cf8d33 (genl_mutex){+.+.}, at: genl_lock net/netlink/genetlink.c:33 [inline] #2: 0000000000cf8d33 (genl_mutex){+.+.}, at: genl_lock_dumpit+0x41/0xa0 net/netlink/genetlink.c:479 #3: 000000005e83112e (rtnl_mutex){+.+.}, at: rtnl_lock+0x17/0x20 net/core/rtnetlink.c:74 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 889 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: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: 7297 Comm: udevd Not tainted 4.16.0+ #2 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:arch_atomic_inc arch/x86/include/asm/atomic.h:96 [inline] RIP: 0010:atomic_inc include/asm-generic/atomic-instrumented.h:103 [inline] RIP: 0010:__lock_acquire+0x298/0x5130 kernel/locking/lockdep.c:3323 RSP: 0018:ffff8801db006c60 EFLAGS: 00000006 RAX: fffffbfff13fec3e RBX: ffffffff89ff60b0 RCX: ffffffff815b5411 RDX: 0000000000000001 RSI: 0000000000000004 RDI: ffffffff89ff61e8 RBP: ffff8801db006ff0 R08: fffffbfff13fec3e R09: fffffbfff13fec3d R10: fffffbfff13fec3d R11: ffffffff89ff61eb R12: 0000000000000001 R13: 0000000000000000 R14: 0000000000000002 R15: ffffffff88b8df60 FS: 00007f0f463a07a0(0000) GS:ffff8801db000000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f0f463a7000 CR3: 00000001bfef1000 CR4: 00000000001426f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: lock_acquire+0x1dc/0x520 kernel/locking/lockdep.c:3920 rcu_lock_acquire include/linux/rcupdate.h:246 [inline] rcu_read_lock+0x2b/0x70 include/linux/rcupdate.h:632 select_task_rq_fair+0x32e/0x3810 kernel/sched/fair.c:6628 select_task_rq kernel/sched/core.c:1528 [inline] try_to_wake_up+0x4bc/0x1180 kernel/sched/core.c:2038 wake_up_process+0x10/0x20 kernel/sched/core.c:2126 process_timeout+0x31/0x40 kernel/time/timer.c:1730 call_timer_fn+0x230/0x940 kernel/time/timer.c:1326 expire_timers kernel/time/timer.c:1363 [inline] __run_timers+0x79e/0xc50 kernel/time/timer.c:1666 run_timer_softirq+0x4c/0x70 kernel/time/timer.c:1692 __do_softirq+0x2e0/0xaf5 kernel/softirq.c:285 invoke_softirq kernel/softirq.c:365 [inline] irq_exit+0x1d1/0x200 kernel/softirq.c:405 exiting_irq arch/x86/include/asm/apic.h:525 [inline] smp_apic_timer_interrupt+0x17e/0x710 arch/x86/kernel/apic/apic.c:1052 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:862 RIP: 0010:arch_local_irq_restore arch/x86/include/asm/paravirt.h:783 [inline] RIP: 0010:kmem_cache_free+0xb3/0x2d0 mm/slab.c:3757 RSP: 0018:ffff88018efbf768 EFLAGS: 00000282 ORIG_RAX: ffffffffffffff13 RAX: 0000000000000007 RBX: ffff8801c7177a38 RCX: 1ffff1003700a12b RDX: 0000000000000000 RSI: ffff8801b8050938 RDI: 0000000000000282 RBP: ffff88018efbf788 R08: ffff8801b8050938 R09: 0000000000000006 R10: ffff8801b8050100 R11: 0000000000000000 R12: ffff8801dad48680 R13: 0000000000000282 R14: ffffffff81a98471 R15: ffff8801c7177a38 anon_vma_free mm/rmap.c:123 [inline] __put_anon_vma+0x251/0x610 mm/rmap.c:1723 put_anon_vma include/linux/rmap.h:115 [inline] unlink_anon_vmas+0x6c9/0xa40 mm/rmap.c:415 free_pgtables+0xe6/0x380 mm/memory.c:627 unmap_region+0x3d0/0x550 mm/mmap.c:2530 do_munmap+0x617/0xf90 mm/mmap.c:2744 vm_munmap+0x120/0x1a0 mm/mmap.c:2763 SYSC_munmap mm/mmap.c:2773 [inline] SyS_munmap+0x25/0x30 mm/mmap.c:2770 do_syscall_64+0x29e/0x9d0 arch/x86/entry/common.c:287 entry_SYSCALL_64_after_hwframe+0x42/0xb7 RIP: 0033:0x7f0f45ab0d37 RSP: 002b:00007ffc46dff368 EFLAGS: 00000206 ORIG_RAX: 000000000000000b RAX: ffffffffffffffda RBX: 00000000023cd640 RCX: 00007f0f45ab0d37 RDX: 0000000000000000 RSI: 0000000000001000 RDI: 00007f0f463a7000 RBP: 0000000000000000 R08: 00007f0f463a07a0 R09: 0000000000000000 R10: 1999999999999999 R11: 0000000000000206 R12: 0000000000000000 R13: 0000000000420298 R14: 00007ffc46dff7f2 R15: 000000000000000b Code: ff ff ff 48 8d bb 38 01 00 00 be 04 00 00 00 4c 89 9c 24 88 00 00 00 44 89 84 24 90 00 00 00 e8 6f 60 57 00 f0 ff 83 38 01 00 00 <4c> 8b 9c 24 88 00 00 00 44 8b 84 24 90 00 00 00 49 8d 83 30 08 INFO: NMI handler (nmi_cpu_backtrace_handler) took too long to run: 1.553 msecs