unregister_netdevice: waiting for lo to become free. Usage count = 8 unregister_netdevice: waiting for lo to become free. Usage count = 8 unregister_netdevice: waiting for lo to become free. Usage count = 8 unregister_netdevice: waiting for lo to become free. Usage count = 8 unregister_netdevice: waiting for lo to become free. Usage count = 8 INFO: task syz-executor7:12468 blocked for more than 120 seconds. Not tainted 4.16.0+ #1 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor7 D25096 12468 9283 0x00000004 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 __rwsem_down_write_failed_common+0x919/0x15d0 kernel/locking/rwsem-xadd.c:566 rwsem_down_write_failed+0xe/0x10 kernel/locking/rwsem-xadd.c:595 call_rwsem_down_write_failed+0x17/0x30 arch/x86/lib/rwsem.S:117 __down_write arch/x86/include/asm/rwsem.h:142 [inline] down_write+0xa2/0x120 kernel/locking/rwsem.c:72 register_netdevice_notifier+0xb4/0x8f0 net/core/dev.c:1629 bcm_init+0x259/0x300 net/can/bcm.c:1484 can_create+0x28a/0x4b0 net/can/af_can.c:183 __sock_create+0x526/0x920 net/socket.c:1285 sock_create net/socket.c:1325 [inline] __sys_socket+0x100/0x250 net/socket.c:1355 SYSC_socket net/socket.c:1364 [inline] SyS_socket+0x24/0x30 net/socket.c:1362 do_syscall_64+0x29e/0x9d0 arch/x86/entry/common.c:287 entry_SYSCALL_64_after_hwframe+0x42/0xb7 RIP: 0033:0x455279 RSP: 002b:00007f342f451c68 EFLAGS: 00000246 ORIG_RAX: 0000000000000029 RAX: ffffffffffffffda RBX: 00007f342f4526d4 RCX: 0000000000455279 RDX: 0000000000000002 RSI: 0000000000000002 RDI: 000000000000001d RBP: 000000000072bea0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 0000000000000613 R14: 00000000006fc268 R15: 0000000000000000 Showing all locks held in the system: 3 locks held by kworker/u4:0/6: #0: 000000000fd4c7c4 ((wq_completion)"%s""netns"){+.+.}, at: __write_once_size include/linux/compiler.h:215 [inline] #0: 000000000fd4c7c4 ((wq_completion)"%s""netns"){+.+.}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline] #0: 000000000fd4c7c4 ((wq_completion)"%s""netns"){+.+.}, at: atomic64_set include/asm-generic/atomic-instrumented.h:40 [inline] #0: 000000000fd4c7c4 ((wq_completion)"%s""netns"){+.+.}, at: atomic_long_set include/asm-generic/atomic-long.h:57 [inline] #0: 000000000fd4c7c4 ((wq_completion)"%s""netns"){+.+.}, at: set_work_data kernel/workqueue.c:617 [inline] #0: 000000000fd4c7c4 ((wq_completion)"%s""netns"){+.+.}, at: set_work_pool_and_clear_pending kernel/workqueue.c:644 [inline] #0: 000000000fd4c7c4 ((wq_completion)"%s""netns"){+.+.}, at: process_one_work+0xaef/0x1b50 kernel/workqueue.c:2116 #1: 00000000921ffdab (net_cleanup_work){+.+.}, at: process_one_work+0xb46/0x1b50 kernel/workqueue.c:2120 #2: 00000000a72d9f7b (pernet_ops_rwsem){++++}, at: cleanup_net+0x11a/0xb20 net/core/net_namespace.c:490 2 locks held by khungtaskd/888: #0: 00000000723513dd (rcu_read_lock){....}, at: check_hung_uninterruptible_tasks kernel/hung_task.c:175 [inline] #0: 00000000723513dd (rcu_read_lock){....}, at: watchdog+0x1ff/0xf60 kernel/hung_task.c:249 #1: 00000000b1e241f0 (tasklist_lock){.+.+}, at: debug_show_all_locks+0xde/0x34a kernel/locking/lockdep.c:4470 2 locks held by getty/4466: #0: 0000000035a3592b (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 00000000513860f3 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4467: #0: 000000007cc3708e (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 00000000567fa835 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4468: #0: 000000001fcdd5ac (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 000000003bcb32a6 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4469: #0: 0000000004217cff (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 0000000032ee1e94 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4470: #0: 0000000067b537de (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 00000000bdcd93ba (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4471: #0: 000000005f35dc84 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 000000002b2f4cad (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4472: #0: 00000000aa5c1e9e (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 000000008842be5e (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 1 lock held by syz-executor7/12468: #0: 00000000a72d9f7b (pernet_ops_rwsem){++++}, at: register_netdevice_notifier+0xb4/0x8f0 net/core/dev.c:1629 1 lock held by syz-executor7/12471: #0: 00000000a72d9f7b (pernet_ops_rwsem){++++}, at: register_netdevice_notifier+0xb4/0x8f0 net/core/dev.c:1629 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 888 Comm: khungtaskd Not tainted 4.16.0+ #1 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: 0 Comm: swapper/0 Not tainted 4.16.0+ #1 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:debug_lockdep_rcu_enabled.part.1+0xf/0x60 kernel/rcu/update.c:298 RSP: 0018:ffff8801db007bd8 EFLAGS: 00000002 RAX: dffffc0000000000 RBX: 1ffff1003b600f85 RCX: 0000000000000000 RDX: 0000000000000004 RSI: 0000000000000001 RDI: ffffffff88e77980 RBP: ffff8801db007be0 R08: 0000000000000000 R09: 0000000000000000 R10: ffffffff88a765f8 R11: ffffffff88a75dc0 R12: ffff8801db007d08 R13: ffffffff8a4d78c8 R14: ffff8801d8777b90 R15: 1ffff1003b600f91 FS: 0000000000000000(0000) GS:ffff8801db000000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000000000132c000 CR3: 00000001afc6e000 CR4: 00000000001406f0 DR0: 0000000020000000 DR1: 0000000020000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600 Call Trace: debug_lockdep_rcu_enabled+0x77/0x90 kernel/rcu/update.c:300 trace_lock_release include/trace/events/lock.h:58 [inline] lock_release+0x578/0xa10 kernel/locking/lockdep.c:3938 seqcount_lockdep_reader_access include/linux/seqlock.h:82 [inline] read_seqcount_begin include/linux/seqlock.h:164 [inline] ktime_get+0x15b/0x430 kernel/time/timekeeping.c:738 tick_nohz_start_idle kernel/time/tick-sched.c:546 [inline] tick_nohz_irq_exit+0x7e/0x100 kernel/time/tick-sched.c:1018 tick_irq_exit kernel/softirq.c:387 [inline] irq_exit+0x1bb/0x200 kernel/softirq.c:407 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:native_safe_halt+0x6/0x10 arch/x86/include/asm/irqflags.h:54 RSP: 0018:ffffffff88a07bc0 EFLAGS: 00000282 ORIG_RAX: ffffffffffffff13 RAX: dffffc0000000000 RBX: 1ffffffff1140f7b RCX: 0000000000000000 RDX: 1ffffffff11630f0 RSI: 0000000000000001 RDI: ffffffff88b18780 RBP: ffffffff88a07bc0 R08: ffffed003b6046c3 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 R13: ffffffff88a07c78 R14: ffffffff8958d860 R15: 0000000000000000 arch_safe_halt arch/x86/include/asm/paravirt.h:94 [inline] default_idle+0xc2/0x440 arch/x86/kernel/process.c:354 arch_cpu_idle+0x10/0x20 arch/x86/kernel/process.c:345 default_idle_call+0x6d/0x90 kernel/sched/idle.c:93 cpuidle_idle_call kernel/sched/idle.c:153 [inline] do_idle+0x395/0x560 kernel/sched/idle.c:262 cpu_startup_entry+0x104/0x120 kernel/sched/idle.c:368 rest_init+0xe1/0xe4 init/main.c:441 start_kernel+0x906/0x92d init/main.c:737 x86_64_start_reservations+0x29/0x2b arch/x86/kernel/head64.c:443 x86_64_start_kernel+0x76/0x79 arch/x86/kernel/head64.c:424 secondary_startup_64+0xa5/0xb0 arch/x86/kernel/head_64.S:242 Code: ff 48 8b 7d c8 e8 c2 70 50 00 e9 9c fd ff ff 0f 1f 00 66 2e 0f 1f 84 00 00 00 00 00 48 b8 00 00 00 00 00 fc ff df 55 48 89 e5 53 <65> 48 8b 1c 25 c0 ed 01 00 48 8d bb 34 08 00 00 48 89 fa 48 c1