unregister_netdevice: waiting for lo to become free. Usage count = 1
INFO: task syz-executor6:6848 blocked for more than 120 seconds.
      Not tainted 4.9.59-g1f46cae #78
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
 ffff8801d8898000 ffff8801c5e2a4c0 ffff8801d21cf9c0 ffff8801d8e04800
 ffff8801db321518 ffff8801d8f4f9f8 ffffffff838988eb 0000000000000246
 ffff8801d8898000 0000000000000000 ffff8801db321e40 ffff8801db321e68
Call Trace:
 [<ffffffff83899e8f>] schedule+0x7f/0x1b0 kernel/sched/core.c:3626
 [<ffffffff8389a813>] schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3659
 [<ffffffff8389fe22>] __mutex_lock_common kernel/locking/mutex.c:582 [inline]
 [<ffffffff8389fe22>] mutex_lock_nested+0x312/0x870 kernel/locking/mutex.c:621
 [<ffffffff82f14ab5>] copy_net_ns+0x155/0x280 net/core/net_namespace.c:387
 [<ffffffff8119e27f>] create_new_namespaces+0x37f/0x730 kernel/nsproxy.c:106
 [<ffffffff8119e8c1>] copy_namespaces+0x291/0x320 kernel/nsproxy.c:164
 [<ffffffff8112bb99>] copy_process.part.51+0x1c99/0x5d40 kernel/fork.c:1667
 [<ffffffff811300d0>] copy_process kernel/fork.c:1491 [inline]
 [<ffffffff811300d0>] _do_fork+0x1c0/0xd70 kernel/fork.c:1949
 [<ffffffff81130d57>] SYSC_clone kernel/fork.c:2059 [inline]
 [<ffffffff81130d57>] SyS_clone+0x37/0x50 kernel/fork.c:2053
 [<ffffffff81006517>] do_syscall_64+0x197/0x490 arch/x86/entry/common.c:280
 [<ffffffff838aa18d>] entry_SYSCALL64_slow_path+0x25/0x25
INFO: lockdep is turned off.
NMI backtrace for cpu 0
CPU: 0 PID: 513 Comm: khungtaskd Not tainted 4.9.59-g1f46cae #78
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801d8927d00 ffffffff81d911c9 0000000000000000 0000000000000000
 0000000000000000 0000000000000001 ffffffff810bd230 ffff8801d8927d38
 ffffffff81d9c2ed 0000000000000000 0000000000000000 ffff8801d8898418
Call Trace:
 [<ffffffff81d911c9>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81d911c9>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff81d9c2ed>] nmi_cpu_backtrace+0xfd/0x120 lib/nmi_backtrace.c:99
 [<ffffffff81d9c427>] nmi_trigger_cpumask_backtrace+0x117/0x190 lib/nmi_backtrace.c:60
 [<ffffffff810bd324>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37
 [<ffffffff81372220>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline]
 [<ffffffff81372220>] check_hung_task kernel/hung_task.c:125 [inline]
 [<ffffffff81372220>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline]
 [<ffffffff81372220>] watchdog+0x6f0/0xa70 kernel/hung_task.c:239
 [<ffffffff8119ad0d>] kthread+0x26d/0x300 kernel/kthread.c:211
 [<ffffffff838aa36a>] ret_from_fork+0x2a/0x40 arch/x86/entry/entry_64.S:433
NMI backtrace for cpu 1
CPU: 1 PID: 3126 Comm: rsyslogd Not tainted 4.9.59-g1f46cae #78
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8801cf6c1800 task.stack: ffff8801d0c20000
RIP: 0010:[<ffffffff81248647>] 
c [<ffffffff81248647>] atomic_cmpxchg arch/x86/include/asm/atomic.h:186 [inline]
RIP: 0010:[<ffffffff81248647>] 
c [<ffffffff81248647>] queued_spin_lock include/asm-generic/qspinlock.h:100 [inline]
RIP: 0010:[<ffffffff81248647>] 
c [<ffffffff81248647>] do_raw_spin_lock+0xb7/0x1e0 kernel/locking/spinlock_debug.c:113
RSP: 0018:ffff8801d0c27b30  EFLAGS: 00000046
RAX: 0000000000000000 RBX: ffffffff844d0aa0 RCX: 1ffff1003a184f3a
RDX: 0000000000000001 RSI: 0000000000000000 RDI: ffffffff844d0aa4
RBP: ffff8801d0c27b50 R08: 0000000000000001 R09: 0000000000000001
R10: 0000000000000000 R11: ffff8801cf6c1800 R12: ffffffff844d0aa8
R13: ffffffff844d0ab0 R14: 000000000003cc80 R15: 0000000000000e8e
FS:  00007f38ef6c5700(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffd0ab04128 CR3: 00000001caf26000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 ffffffff844d0aa0
c 0000000000000171
c ffff8801a9304480
c 000000000003cc80
c
 ffff8801d0c27b70
c ffffffff838a965a
c ffffffff81267873
c 0000000000000057
c
 ffff8801d0c27c58
c ffffffff81267873
c ffffffff81d9c7fa
c 1ffff1003a184f76
c
Call Trace:
 [<ffffffff838a965a>] __raw_spin_lock_irq include/linux/spinlock_api_smp.h:131 [inline]
 [<ffffffff838a965a>] _raw_spin_lock_irq+0x4a/0x60 kernel/locking/spinlock.c:167
 [<ffffffff81267873>] syslog_print kernel/printk/printk.c:1290 [inline]
 [<ffffffff81267873>] do_syslog+0x723/0xa80 kernel/printk/printk.c:1459
 [<ffffffff816e88e4>] kmsg_read+0x74/0xa0 fs/proc/kmsg.c:39
 [<ffffffff816bf5cf>] proc_reg_read+0xef/0x170 fs/proc/inode.c:202
 [<ffffffff8156c5f3>] __vfs_read+0x103/0x670 fs/read_write.c:452
 [<ffffffff8156db87>] vfs_read+0x107/0x330 fs/read_write.c:475
 [<ffffffff81571829>] SYSC_read fs/read_write.c:591 [inline]
 [<ffffffff81571829>] SyS_read+0xd9/0x1b0 fs/read_write.c:584
 [<ffffffff838aa0c5>] entry_SYSCALL_64_fastpath+0x23/0xc6
Code: 
c48 
cc1 
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cb6 
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cc0 
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c00 
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c08 
c74 
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c00 
c00 
c00 
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cb1 
c13 
c<85> 
cc0 
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c00 
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c00 
c48 
cb8 
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c00 
c00 
cfc 
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c4c 
c89 
ce2 
c