unregister_netdevice: waiting for syz5 to become free. Usage count = 1
INFO: task kworker/u8:1:1192 blocked for more than 120 seconds.
      Not tainted 4.13.0-rc4-next-20170811 #2
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
kworker/u8:1    D19984  1192      2 0x80000000
Workqueue: netns cleanup_net
Call Trace:
 context_switch kernel/sched/core.c:2786 [inline]
 __schedule+0x8e8/0x2070 kernel/sched/core.c:3362
 schedule+0x108/0x440 kernel/sched/core.c:3422
 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:8612 [inline]
 default_device_exit_batch+0x2ab/0x5d0 net/core/dev.c:8639
 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:2098
 worker_thread+0x223/0x1860 kernel/workqueue.c:2233
 kthread+0x35e/0x430 kernel/kthread.c:231
 ret_from_fork+0x2a/0x40 arch/x86/entry/entry_64.S:431
INFO: lockdep is turned off.
NMI backtrace for cpu 1
CPU: 1 PID: 636 Comm: khungtaskd Not tainted 4.13.0-rc4-next-20170811 #2
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 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:431
Sending NMI from CPU 1 to CPUs 0,2-3:
NMI backtrace for cpu 2
CPU: 2 PID: 2923 Comm: rs:main Q:Reg Not tainted 4.13.0-rc4-next-20170811 #2
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
task: ffff88003ac34740 task.stack: ffff880038780000
RIP: 0033:0x4210c0
RSP: 002b:00007ff090b1c420 EFLAGS: 00000246
RAX: 000000000065e478 RBX: 000000000243aa38 RCX: 0000000000000001
RDX: 0000000000000001 RSI: 0000000002448820 RDI: 000000000044ad88
RBP: 0000000000000000 R08: 00000000024488d0 R09: 0000000000000b6b
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000001
R13: 0000000000000000 R14: 0000000002448820 R15: 000000000245ec40
FS:  00007ff090b25700(0000) GS:ffff88006de00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000c439261000 CR3: 000000003a75a000 CR4: 00000000000006e0
NMI backtrace for cpu 0 skipped: idling at pc 0xffffffff84d66e06
NMI backtrace for cpu 3 skipped: idling at pc 0xffffffff84d66e06