unregister_netdevice: waiting for syz2 to become free. Usage count = 1 INFO: task kworker/u4:7:7700 blocked for more than 120 seconds. Not tainted 4.13.0-rc3+ #14 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. kworker/u4:7 D15696 7700 2 0x00000000 Workqueue: netns cleanup_net 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_timeout+0x1ce/0x250 kernel/time/timer.c:1688 wait_woken+0x10f/0x280 kernel/sched/wait.c:363 rtnl_lock_unregistering net/core/dev.c:8572 [inline] default_device_exit_batch+0x2ab/0x5d0 net/core/dev.c:8599 ops_exit_list.isra.6+0x100/0x150 net/core/net_namespace.c:145 cleanup_net+0x5c7/0xb50 net/core/net_namespace.c:483 process_one_work+0xbf3/0x1bc0 kernel/workqueue.c:2097 worker_thread+0x223/0x1860 kernel/workqueue.c:2231 kthread+0x35e/0x430 kernel/kthread.c:231 ret_from_fork+0x2a/0x40 arch/x86/entry/entry_64.S:425 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/2890: #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/2891: #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/2892: #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/2893: #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/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 3 locks held by kworker/u4:7/7700: #0: ("%s""netns"){.+.+.+}, at: [] __write_once_size include/linux/compiler.h:279 [inline] #0: ("%s""netns"){.+.+.+}, at: [] atomic64_set arch/x86/include/asm/atomic64_64.h:33 [inline] #0: ("%s""netns"){.+.+.+}, at: [] atomic_long_set include/asm-generic/atomic-long.h:56 [inline] #0: ("%s""netns"){.+.+.+}, at: [] set_work_data kernel/workqueue.c:617 [inline] #0: ("%s""netns"){.+.+.+}, at: [] set_work_pool_and_clear_pending kernel/workqueue.c:644 [inline] #0: ("%s""netns"){.+.+.+}, at: [] process_one_work+0xadf/0x1bc0 kernel/workqueue.c:2090 #1: (net_cleanup_work){+.+.+.}, at: [] process_one_work+0xb32/0x1bc0 kernel/workqueue.c:2094 #2: (net_mutex){+.+.+.}, at: [] cleanup_net+0x247/0xb50 net/core/net_namespace.c:449 1 lock held by syz-executor2/11760: #0: (net_mutex){+.+.+.}, at: [] copy_net_ns+0x239/0x580 net/core/net_namespace.c:409 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 553 Comm: khungtaskd Not tainted 4.13.0-rc3+ #14 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 CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.13.0-rc3+ #14 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 task: ffffffff8502b340 task.stack: ffffffff85000000 RIP: 0010:reschedule_interrupt+0x0/0xa0 arch/x86/entry/entry_64.S:725 RSP: 0018:ffffffff85007cb8 EFLAGS: 00000082 RAX: dffffc0000000000 RBX: 1ffffffff0a00f9f RCX: 0000000000000000 RDX: 1ffffffff0a193dc RSI: 0000000000000001 RDI: ffffffff850c9ee0 RBP: ffffffff85007ce0 R08: ffffffff84e38a80 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: ffffffff850c9ed0 R13: ffffffff85007d98 R14: 0000000000000000 R15: ffffffff8502b340 FS: 0000000000000000(0000) GS:ffff8801dc000000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000000000252b000 CR3: 00000001d5a24000 CR4: 00000000001406f0 DR0: 0000000020001008 DR1: 0000000020001008 DR2: 0000000020000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600 Call Trace: arch_safe_halt arch/x86/include/asm/paravirt.h:98 [inline] default_idle+0xbf/0x460 arch/x86/kernel/process.c:341 arch_cpu_idle+0xa/0x10 arch/x86/kernel/process.c:332 default_idle_call+0x36/0x90 kernel/sched/idle.c:98 cpuidle_idle_call kernel/sched/idle.c:156 [inline] do_idle+0x256/0x3b0 kernel/sched/idle.c:246 cpu_startup_entry+0x18/0x20 kernel/sched/idle.c:351 rest_init+0xfb/0x100 init/main.c:436 start_kernel+0x70d/0x733 init/main.c:701 x86_64_start_reservations+0x2a/0x2c arch/x86/kernel/head64.c:317 x86_64_start_kernel+0x13c/0x149 arch/x86/kernel/head64.c:298 secondary_startup_64+0x9f/0x9f arch/x86/kernel/head_64.S:219 Code: e7 65 ff 04 25 54 64 01 00 65 48 0f 44 24 25 58 64 01 00 57 e8 21 50 b6 fc e8 bd 31 00 00 e9 cb e6 ff ff 0f 1f 84 00 00 00 00 00 <0f> 1f 00 68 02 ff ff ff fc 48 83 c4 88 4c 89 5c 24 30 4c 89 54