unregister_netdevice: waiting for lo to become free. Usage count = 1 unregister_netdevice: waiting for lo to become free. Usage count = 1 unregister_netdevice: waiting for lo to become free. Usage count = 1 unregister_netdevice: waiting for lo to become free. Usage count = 1 unregister_netdevice: waiting for lo to become free. Usage count = 1 INFO: task syz-executor3:7540 blocked for more than 120 seconds. Not tainted 4.16.0+ #17 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor3 D20712 7540 4579 0x80000002 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 __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 unregister_netdevice_notifier+0x98/0x520 net/core/dev.c:1698 raw_release+0x56/0x700 net/can/raw.c:358 sock_release+0x96/0x1b0 net/socket.c:594 sock_close+0x16/0x20 net/socket.c:1149 __fput+0x34d/0x890 fs/file_table.c:209 ____fput+0x15/0x20 fs/file_table.c:243 task_work_run+0x1e4/0x290 kernel/task_work.c:113 exit_task_work include/linux/task_work.h:22 [inline] do_exit+0x1aee/0x2730 kernel/exit.c:865 do_group_exit+0x16f/0x430 kernel/exit.c:968 get_signal+0x886/0x1960 kernel/signal.c:2469 do_signal+0x98/0x2040 arch/x86/kernel/signal.c:810 exit_to_usermode_loop+0x28a/0x310 arch/x86/entry/common.c:162 prepare_exit_to_usermode arch/x86/entry/common.c:196 [inline] syscall_return_slowpath arch/x86/entry/common.c:265 [inline] do_syscall_64+0x792/0x9d0 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x42/0xb7 RIP: 0033:0x455259 RSP: 002b:00007fa4c15dec68 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: 0000000000000000 RBX: 00007fa4c15df6d4 RCX: 0000000000455259 RDX: 0000000020000980 RSI: 00000000000089a0 RDI: 000000000000001e RBP: 000000000072bea0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 0000000000000364 R14: 00000000006f8200 R15: 0000000000000000 Showing all locks held in the system: 3 locks held by kworker/u4:3/616: #0: 00000000b64e5ad1 ((wq_completion)"%s""netns"){+.+.}, at: __write_once_size include/linux/compiler.h:215 [inline] #0: 00000000b64e5ad1 ((wq_completion)"%s""netns"){+.+.}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline] #0: 00000000b64e5ad1 ((wq_completion)"%s""netns"){+.+.}, at: atomic64_set include/asm-generic/atomic-instrumented.h:40 [inline] #0: 00000000b64e5ad1 ((wq_completion)"%s""netns"){+.+.}, at: atomic_long_set include/asm-generic/atomic-long.h:57 [inline] #0: 00000000b64e5ad1 ((wq_completion)"%s""netns"){+.+.}, at: set_work_data kernel/workqueue.c:617 [inline] #0: 00000000b64e5ad1 ((wq_completion)"%s""netns"){+.+.}, at: set_work_pool_and_clear_pending kernel/workqueue.c:644 [inline] #0: 00000000b64e5ad1 ((wq_completion)"%s""netns"){+.+.}, at: process_one_work+0xaef/0x1b50 kernel/workqueue.c:2116 #1: 00000000e390e322 (net_cleanup_work){+.+.}, at: process_one_work+0xb46/0x1b50 kernel/workqueue.c:2120 #2: 00000000c2c6ba1f (pernet_ops_rwsem){++++}, at: cleanup_net+0x11a/0xb20 net/core/net_namespace.c:490 2 locks held by khungtaskd/888: #0: 00000000595f34bc (rcu_read_lock){....}, at: check_hung_uninterruptible_tasks kernel/hung_task.c:175 [inline] #0: 00000000595f34bc (rcu_read_lock){....}, at: watchdog+0x1ff/0xf60 kernel/hung_task.c:249 #1: 00000000d545ea2a (tasklist_lock){.+.+}, at: debug_show_all_locks+0xde/0x34a kernel/locking/lockdep.c:4470 2 locks held by getty/4505: #0: 00000000f768bf0a (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 000000006bfbb7c8 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4506: #0: 00000000a076c4bd (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 00000000196ad80d (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4507: #0: 000000007a6be71c (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 00000000333f8737 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4508: #0: 0000000091b13a68 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 00000000b4921820 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4509: #0: 000000005772db47 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 00000000ff68ec45 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4510: #0: 00000000408fa7b1 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 00000000fee1158f (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 2 locks held by getty/4511: #0: 00000000948c87f3 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 000000009669b0df (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131 1 lock held by syz-executor3/7540: #0: 00000000c2c6ba1f (pernet_ops_rwsem){++++}, at: unregister_netdevice_notifier+0x98/0x520 net/core/dev.c:1698 1 lock held by syz-executor3/7638: #0: 00000000c2c6ba1f (pernet_ops_rwsem){++++}, at: copy_net_ns+0x297/0x4c0 net/core/net_namespace.c:432 1 lock held by syz-executor1/7640: #0: 00000000c2c6ba1f (pernet_ops_rwsem){++++}, at: copy_net_ns+0x297/0x4c0 net/core/net_namespace.c:432 ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 888 Comm: khungtaskd Not tainted 4.16.0+ #17 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 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.16.0+ #17 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:trace_hardirqs_off_caller+0x114/0x2c0 kernel/locking/lockdep.c:2913 RSP: 0018:ffff8801db107400 EFLAGS: 00000002 RAX: 0000000000000001 RBX: ffff8801d9ed4340 RCX: 0000000000000000 RDX: 1ffff1003b3da970 RSI: 0000000000000000 RDI: ffff8801d9ed4b80 RBP: ffff8801db107418 R08: ffff8801d9ed4340 R09: ffffed003b6258b1 R10: ffffed003b6258b1 R11: ffff8801db12c58b R12: ffff8801d9ed4340 R13: ffffffff874fb534 R14: ffff8801db107ab8 R15: 0000000000000040 FS: 0000000000000000(0000) GS:ffff8801db100000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000001ef3000 CR3: 00000001cccd3000 CR4: 00000000001406e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: trace_hardirqs_off+0xd/0x10 kernel/locking/lockdep.c:2928 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:108 [inline] _raw_spin_lock_irqsave+0x74/0xc0 kernel/locking/spinlock.c:152 rq_lock_irqsave kernel/sched/sched.h:1776 [inline] update_blocked_averages+0x124/0x1720 kernel/sched/fair.c:7664 _nohz_idle_balance+0x59a/0x7e0 kernel/sched/fair.c:9657 nohz_idle_balance kernel/sched/fair.c:9710 [inline] run_rebalance_domains+0x2be/0x4a0 kernel/sched/fair.c:9893 __do_softirq+0x2e0/0xaf5 kernel/softirq.c:285 invoke_softirq kernel/softirq.c:365 [inline] irq_exit+0x1d1/0x200 kernel/softirq.c:405 scheduler_ipi+0x52b/0xa30 kernel/sched/core.c:1778 smp_reschedule_interrupt+0xed/0x660 arch/x86/kernel/smp.c:277 reschedule_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:886 RIP: 0010:native_safe_halt+0x6/0x10 arch/x86/include/asm/irqflags.h:54 RSP: 0018:ffff8801d9edfcb0 EFLAGS: 00000286 ORIG_RAX: ffffffffffffff02 RAX: dffffc0000000000 RBX: 1ffff1003b3dbf99 RCX: 0000000000000000 RDX: 1ffffffff11630e0 RSI: 0000000000000001 RDI: ffffffff88b18700 RBP: ffff8801d9edfcb0 R08: ffff8801d9ed4340 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000001 R13: ffff8801d9edfd68 R14: ffffffff88b186f0 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:151 [inline] do_idle+0x2f4/0x3c0 kernel/sched/idle.c:241 cpu_startup_entry+0x104/0x120 kernel/sched/idle.c:346 start_secondary+0x426/0x5b0 arch/x86/kernel/smpboot.c:267 secondary_startup_64+0xa5/0xb0 arch/x86/kernel/head_64.S:242 Code: 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 0f b6 04 02 84 c0 74 08 3c 03 0f 8e 61 01 00 00 8b 83 40 08 00 00 85 c0 0f 84 a4 00 00 00 <48> 8d bb 30 08 00 00 48 b8 00 00 00 00 00 fc ff df c7 83 40 08