INFO: task syz-executor3:4212 blocked for more than 120 seconds. Not tainted 4.16.0-rc1+ #314 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor3 D19392 4212 1 0x80000006 Call Trace: context_switch kernel/sched/core.c:2862 [inline] __schedule+0x905/0x2070 kernel/sched/core.c:3440 schedule+0xf5/0x430 kernel/sched/core.c:3499 schedule_preempt_disabled+0x10/0x20 kernel/sched/core.c:3557 __mutex_lock_common kernel/locking/mutex.c:833 [inline] __mutex_lock+0xaad/0x1a80 kernel/locking/mutex.c:893 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908 rtnl_lock+0x17/0x20 net/core/rtnetlink.c:74 tun_detach drivers/net/tun.c:745 [inline] tun_chr_close+0x37/0x60 drivers/net/tun.c:3179 __fput+0x327/0x7e0 fs/file_table.c:209 ____fput+0x15/0x20 fs/file_table.c:243 task_work_run+0x199/0x270 kernel/task_work.c:113 exit_task_work include/linux/task_work.h:22 [inline] do_exit+0x9bb/0x1ad0 kernel/exit.c:865 do_group_exit+0x149/0x400 kernel/exit.c:968 get_signal+0x73a/0x16d0 kernel/signal.c:2469 do_signal+0x90/0x1e90 arch/x86/kernel/signal.c:809 exit_to_usermode_loop+0x258/0x2f0 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+0x6e5/0x940 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x42/0xb7 RIP: 0033:0x40dd9a RSP: 002b:0000000000a2ed68 EFLAGS: 00000246 ORIG_RAX: 000000000000003d RAX: fffffffffffffe00 RBX: 0000000000000051 RCX: 000000000040dd9a RDX: 0000000040000000 RSI: 0000000000a2ed94 RDI: ffffffffffffffff RBP: 0000000000a2eda0 R08: 0000000000000001 R09: 0000000002625940 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000a2f420 R13: 0000000000000195 R14: 0000000000000000 R15: 0000000002625914 Showing all locks held in the system: 2 locks held by khungtaskd/756: #0: (rcu_read_lock){....}, at: [<000000006b36ceac>] check_hung_uninterruptible_tasks kernel/hung_task.c:175 [inline] #0: (rcu_read_lock){....}, at: [<000000006b36ceac>] watchdog+0x1c5/0xd60 kernel/hung_task.c:249 #1: (tasklist_lock){.+.+}, at: [<000000005abe57a4>] debug_show_all_locks+0xd3/0x3d0 kernel/locking/lockdep.c:4470 2 locks held by getty/4132: #0: (&tty->ldisc_sem){++++}, at: [<00000000595260b7>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000c36b84df>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 2 locks held by getty/4133: #0: (&tty->ldisc_sem){++++}, at: [<00000000595260b7>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000c36b84df>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 2 locks held by getty/4134: #0: (&tty->ldisc_sem){++++}, at: [<00000000595260b7>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000c36b84df>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 2 locks held by getty/4135: #0: (&tty->ldisc_sem){++++}, at: [<00000000595260b7>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000c36b84df>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 2 locks held by getty/4136: #0: (&tty->ldisc_sem){++++}, at: [<00000000595260b7>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000c36b84df>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 2 locks held by getty/4137: #0: (&tty->ldisc_sem){++++}, at: [<00000000595260b7>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000c36b84df>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 2 locks held by getty/4138: #0: (&tty->ldisc_sem){++++}, at: [<00000000595260b7>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000c36b84df>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 1 lock held by syz-executor3/4212: #0: (rtnl_mutex){+.+.}, at: [<00000000a8309eae>] rtnl_lock+0x17/0x20 net/core/rtnetlink.c:74 3 locks held by kworker/0:2/4726: #0: ((wq_completion)"%s"("ipv6_addrconf")){+.+.}, at: [<00000000302cad21>] process_one_work+0xaaf/0x1af0 kernel/workqueue.c:2084 #1: ((addr_chk_work).work){+.+.}, at: [<0000000095b7c7c2>] process_one_work+0xb01/0x1af0 kernel/workqueue.c:2088 #2: (rtnl_mutex){+.+.}, at: [<00000000a8309eae>] rtnl_lock+0x17/0x20 net/core/rtnetlink.c:74 3 locks held by kworker/0:3/7235: #0: ((wq_completion)"events_power_efficient"){+.+.}, at: [<00000000302cad21>] process_one_work+0xaaf/0x1af0 kernel/workqueue.c:2084 #1: ((reg_check_chans).work){+.+.}, at: [<0000000095b7c7c2>] process_one_work+0xb01/0x1af0 kernel/workqueue.c:2088 #2: (rtnl_mutex){+.+.}, at: [<00000000a8309eae>] rtnl_lock+0x17/0x20 net/core/rtnetlink.c:74 1 lock held by syz-executor6/7622: #0: (sk_lock-AF_INET6){+.+.}, at: [<000000002f175fa6>] lock_sock include/net/sock.h:1463 [inline] #0: (sk_lock-AF_INET6){+.+.}, at: [<000000002f175fa6>] ipv6_getsockopt+0x1c5/0x2e0 net/ipv6/ipv6_sockglue.c:1370 1 lock held by syz-executor6/7641: #0: (rtnl_mutex){+.+.}, at: [<00000000a8309eae>] rtnl_lock+0x17/0x20 net/core/rtnetlink.c:74 1 lock held by syz-executor6/7667: #0: (sk_lock-AF_INET6){+.+.}, at: [<000000002f175fa6>] lock_sock include/net/sock.h:1463 [inline] #0: (sk_lock-AF_INET6){+.+.}, at: [<000000002f175fa6>] ipv6_getsockopt+0x1c5/0x2e0 net/ipv6/ipv6_sockglue.c:1370 1 lock held by syz-executor6/7673: #0: (rtnl_mutex){+.+.}, at: [<00000000a8309eae>] rtnl_lock+0x17/0x20 net/core/rtnetlink.c:74 1 lock held by syz-executor3/7643: #0: (rtnl_mutex){+.+.}, at: [<00000000a8309eae>] rtnl_lock+0x17/0x20 net/core/rtnetlink.c:74 1 lock held by syz-executor2/7648: #0: (rtnl_mutex){+.+.}, at: [<00000000a8309eae>] rtnl_lock+0x17/0x20 net/core/rtnetlink.c:74 1 lock held by syz-executor2/7670: #0: (rtnl_mutex){+.+.}, at: [<00000000a8309eae>] rtnl_lock+0x17/0x20 net/core/rtnetlink.c:74 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 756 Comm: khungtaskd Not tainted 4.16.0-rc1+ #314 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0x194/0x257 lib/dump_stack.c:53 nmi_cpu_backtrace+0x1d2/0x210 lib/nmi_backtrace.c:103 nmi_trigger_cpumask_backtrace+0x122/0x180 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+0x90c/0xd60 kernel/hung_task.c:249 kthread+0x33c/0x400 kernel/kthread.c:238 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:407 Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 skipped: idling at native_safe_halt+0x6/0x10 arch/x86/include/asm/irqflags.h:54