unregister_netdevice: waiting for syz5 to become free. Usage count = 1 INFO: task syz-executor5:31889 blocked for more than 120 seconds. Not tainted 4.13.0-rc4+ #2 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor5 D24304 31889 3019 0x00000004 Call Trace: context_switch kernel/sched/core.c:2771 [inline] __schedule+0x8e8/0x2070 kernel/sched/core.c:3332 schedule+0x108/0x440 kernel/sched/core.c:3391 schedule_preempt_disabled+0x10/0x20 kernel/sched/core.c:3449 __mutex_lock_common kernel/locking/mutex.c:833 [inline] __mutex_lock+0xadf/0x1870 kernel/locking/mutex.c:893 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908 sock_ioctl+0x367/0x440 net/socket.c:1023 vfs_ioctl fs/ioctl.c:45 [inline] do_vfs_ioctl+0x1b1/0x1520 fs/ioctl.c:685 SYSC_ioctl fs/ioctl.c:700 [inline] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:691 entry_SYSCALL_64_fastpath+0x1f/0xbe RIP: 0033:0x4512e9 RSP: 002b:00007faf60c91c08 EFLAGS: 00000216 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 0000000000718150 RCX: 00000000004512e9 RDX: 0000000020b12ff0 RSI: 00000000000089a1 RDI: 000000000000001d RBP: 0000000000000086 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000216 R12: 00000000004bf238 R13: 00000000ffffffff R14: 000000000000001b R15: 0000000000000084 Showing all locks held in the system: 2 locks held by khungtaskd/553: #0: (rcu_read_lock){......}, at: [] check_hung_uninterruptible_tasks kernel/hung_task.c:175 [inline] #0: (rcu_read_lock){......}, at: [] watchdog+0x1c5/0xd60 kernel/hung_task.c:249 #1: (tasklist_lock){.+.+..}, at: [] debug_show_all_locks+0xd2/0x410 kernel/locking/lockdep.c:4417 2 locks held by getty/2894: #0: (&tty->ldisc_sem){++++++}, at: [] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:367 #1: (&ldata->atomic_read_lock){+.+...}, at: [] n_tty_read+0x2ef/0x1a40 drivers/tty/n_tty.c:2133 2 locks held by getty/2895: #0: (&tty->ldisc_sem){++++++}, at: [] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:367 #1: (&ldata->atomic_read_lock){+.+...}, at: [] n_tty_read+0x2ef/0x1a40 drivers/tty/n_tty.c:2133 2 locks held by getty/2896: #0: (&tty->ldisc_sem){++++++}, at: [] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:367 #1: (&ldata->atomic_read_lock){+.+...}, at: [] n_tty_read+0x2ef/0x1a40 drivers/tty/n_tty.c:2133 2 locks held by getty/2897: #0: (&tty->ldisc_sem){++++++}, at: [] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:367 #1: (&ldata->atomic_read_lock){+.+...}, at: [] n_tty_read+0x2ef/0x1a40 drivers/tty/n_tty.c:2133 2 locks held by getty/2898: #0: (&tty->ldisc_sem){++++++}, at: [] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:367 #1: (&ldata->atomic_read_lock){+.+...}, at: [] n_tty_read+0x2ef/0x1a40 drivers/tty/n_tty.c:2133 2 locks held by getty/2899: #0: (&tty->ldisc_sem){++++++}, at: [] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:367 #1: (&ldata->atomic_read_lock){+.+...}, at: [] n_tty_read+0x2ef/0x1a40 drivers/tty/n_tty.c:2133 2 locks held by getty/2900: #0: (&tty->ldisc_sem){++++++}, at: [] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:367 #1: (&ldata->atomic_read_lock){+.+...}, at: [] n_tty_read+0x2ef/0x1a40 drivers/tty/n_tty.c:2133 1 lock held by syz-executor5/31868: #0: (br_ioctl_mutex){+.+.+.}, at: [] sock_ioctl+0x367/0x440 net/socket.c:1023 1 lock held by syz-executor5/31889: #0: (br_ioctl_mutex){+.+.+.}, at: [] sock_ioctl+0x367/0x440 net/socket.c:1023 1 lock held by syz-executor2/31872: #0: (br_ioctl_mutex){+.+.+.}, at: [] sock_ioctl+0x367/0x440 net/socket.c:1023 1 lock held by syz-executor0/31900: #0: (br_ioctl_mutex){+.+.+.}, at: [] sock_ioctl+0x367/0x440 net/socket.c:1023 1 lock held by syz-executor0/31918: #0: (br_ioctl_mutex){+.+.+.}, at: [] sock_ioctl+0x367/0x440 net/socket.c:1023 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 553 Comm: khungtaskd Not tainted 4.13.0-rc4+ #2 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:16 [inline] dump_stack+0x194/0x257 lib/dump_stack.c:52 nmi_cpu_backtrace+0x20e/0x240 lib/nmi_backtrace.c:102 nmi_trigger_cpumask_backtrace+0x122/0x180 lib/nmi_backtrace.c:61 arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37 trigger_all_cpu_backtrace include/linux/nmi.h:105 [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+0x35e/0x430 kernel/kthread.c:231 ret_from_fork+0x2a/0x40 arch/x86/entry/entry_64.S:425 Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 skipped: idling at pc 0xffffffff844a41e6