unregister_netdevice: waiting for lo to become free. Usage count = 3
INFO: task syz-executor4:13203 blocked for more than 120 seconds.
      Not tainted 4.4.113-g202e079 #1
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor4   D ffff8801d15e7878 27296 13203   3388 0x00000002
 ffff8801d15e7878 ffff8801cf415f00 0000000000000000 0000000000000007
 ffff8801cf415f00 dffffc0000000000 ffff8801db21fdb8 ffff8801db21fde0
 ffff8801db21f4d8 ffffffff84217840 ffff8801cf415f00 0000000000000000
Call Trace:
 [<ffffffff83763a1a>] schedule+0x7a/0x1b0 kernel/sched/core.c:3351
 [<ffffffff83764213>] schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3384
 [<ffffffff837687d6>] __mutex_lock_common kernel/locking/mutex.c:582 [inline]
 [<ffffffff837687d6>] mutex_lock_nested+0x306/0x850 kernel/locking/mutex.c:621
 [<ffffffff815d308a>] blkdev_put+0x2a/0x550 fs/block_dev.c:1558
 [<ffffffff815d363b>] blkdev_close+0x8b/0xb0 fs/block_dev.c:1607
 [<ffffffff81522363>] __fput+0x233/0x6d0 fs/file_table.c:208
 [<ffffffff81522885>] ____fput+0x15/0x20 fs/file_table.c:244
 [<ffffffff8118b9d4>] task_work_run+0x104/0x180 kernel/task_work.c:115
 [<ffffffff81132f7a>] exit_task_work include/linux/task_work.h:21 [inline]
 [<ffffffff81132f7a>] do_exit+0x82a/0x2a10 kernel/exit.c:755
 [<ffffffff81139418>] do_group_exit+0x108/0x320 kernel/exit.c:885
 [<ffffffff8115c872>] get_signal+0x4f2/0x1550 kernel/signal.c:2317
 [<ffffffff8100e7fb>] do_signal+0x8b/0x1d40 arch/x86/kernel/signal.c:712
 [<ffffffff810035fa>] exit_to_usermode_loop+0x11a/0x160 arch/x86/entry/common.c:247
 [<ffffffff81006535>] prepare_exit_to_usermode arch/x86/entry/common.c:282 [inline]
 [<ffffffff81006535>] syscall_return_slowpath+0x1b5/0x1f0 arch/x86/entry/common.c:347
 [<ffffffff83771ce9>] int_ret_from_sys_call+0x25/0xa3
1 lock held by syz-executor4/13203:
 #0:  (&bdev->bd_mutex){+.+.+.}, at: [<ffffffff815d308a>] blkdev_put+0x2a/0x550 fs/block_dev.c:1558
Sending NMI to all CPUs:
NMI backtrace for cpu 0
CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.4.113-g202e079 #1
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffffffff84217840 task.stack: ffffffff84200000
RIP: 0010:[<ffffffff810d0536>]  [<ffffffff810d0536>] native_safe_halt+0x6/0x10 arch/x86/include/asm/irqflags.h:49
RSP: 0018:ffffffff84207dc0  EFLAGS: 00000246
RAX: 0000000000000007 RBX: ffffffff847dd788 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000001 RDI: ffffffff842180ac
RBP: ffffffff84207dc0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: fffffbfff0708868 R14: ffffffff847ebaf8 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fff6dfda928 CR3: 00000000b60d6000 CR4: 0000000000160670
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 ffffffff84207df8 ffffffff81027ed5 ffffffff84208000 ffffffff847dd788
 fffffbfff0708868 ffffffff847ebaf8 0000000000000000 ffffffff84207e08
 ffffffff8102945a ffffffff84207e20 ffffffff81220418 dffffc0000000000
Call Trace:
 [<ffffffff81027ed5>] arch_safe_halt arch/x86/include/asm/paravirt.h:117 [inline]
 [<ffffffff81027ed5>] default_idle+0x55/0x3c0 arch/x86/kernel/process.c:291
 [<ffffffff8102945a>] arch_cpu_idle+0xa/0x10 arch/x86/kernel/process.c:282
 [<ffffffff81220418>] default_idle_call+0x48/0x70 kernel/sched/idle.c:93
 [<ffffffff81220b1d>] cpuidle_idle_call kernel/sched/idle.c:157 [inline]
 [<ffffffff81220b1d>] cpu_idle_loop kernel/sched/idle.c:253 [inline]
 [<ffffffff81220b1d>] cpu_startup_entry+0x5fd/0x8f0 kernel/sched/idle.c:301
 [<ffffffff8375ead9>] rest_init+0x189/0x190 init/main.c:410
 [<ffffffff84821811>] start_kernel+0x6b9/0x6ee init/main.c:682
 [<ffffffff84820312>] x86_64_start_reservations+0x2a/0x2c arch/x86/kernel/head64.c:196
 [<ffffffff84820454>] x86_64_start_kernel+0x140/0x163 arch/x86/kernel/head64.c:185
Code: 00 00 00 00 00 55 48 89 e5 fa 5d c3 66 0f 1f 84 00 00 00 00 00 55 48 89 e5 fb 5d c3 66 0f 1f 84 00 00 00 00 00 55 48 89 e5 fb f4 <5d> c3 0f 1f 84 00 00 00 00 00 55 48 89 e5 f4 5d c3 66 0f 1f 84 
NMI backtrace for cpu 1
CPU: 1 PID: 486 Comm: khungtaskd Not tainted 4.4.113-g202e079 #1
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8800bad5af80 task.stack: ffff8800bacd8000
RIP: 0010:[<ffffffff810c3cf7>]  [<ffffffff810c3cf7>] native_apic_mem_write arch/x86/include/asm/apic.h:94 [inline]
RIP: 0010:[<ffffffff810c3cf7>]  [<ffffffff810c3cf7>] __default_send_IPI_dest_field arch/x86/include/asm/ipi.h:119 [inline]
RIP: 0010:[<ffffffff810c3cf7>]  [<ffffffff810c3cf7>] _flat_send_IPI_mask arch/x86/kernel/apic/apic_flat_64.c:61 [inline]
RIP: 0010:[<ffffffff810c3cf7>]  [<ffffffff810c3cf7>] flat_send_IPI_mask+0xf7/0x1a0 arch/x86/kernel/apic/apic_flat_64.c:69
RSP: 0018:ffff8800bacdfcb8  EFLAGS: 00000046
RAX: 0000000003000000 RBX: 0000000000000c00 RCX: 0000000000000000
RDX: 0000000000000c00 RSI: 0000000000000000 RDI: ffffffffff5fb300
RBP: ffff8800bacdfce0 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000001 R12: 0000000000000246
R13: 0000000000000003 R14: ffffffff8426f2e0 R15: 0000000000000002
FS:  0000000000000000(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000c427019000 CR3: 00000000b60d6000 CR4: 0000000000160670
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 ffffffff8426f2e0 ffffffff847ef680 fffffbfff08fd984 dffffc0000000000
 ffff8801db31bca0 ffff8800bacdfd00 ffffffff810b982b ffffffff839f6100
 0000000000000003 ffff8800bacdfd60 ffffffff81d0d6f4 ffffffff8141a093
Call Trace:
 [<ffffffff810b982b>] nmi_raise_cpu_backtrace+0x5b/0x70 arch/x86/kernel/apic/hw_nmi.c:33
 [<ffffffff81d0d6f4>] nmi_trigger_all_cpu_backtrace+0x4a4/0x550 lib/nmi_backtrace.c:85
 [<ffffffff810b98c4>] arch_trigger_all_cpu_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:38
 [<ffffffff81367b6a>] trigger_all_cpu_backtrace include/linux/nmi.h:44 [inline]
 [<ffffffff81367b6a>] check_hung_task kernel/hung_task.c:125 [inline]
 [<ffffffff81367b6a>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline]
 [<ffffffff81367b6a>] watchdog+0x6fa/0xae0 kernel/hung_task.c:238
 [<ffffffff811907d8>] kthread+0x268/0x300 kernel/kthread.c:211
 [<ffffffff83771f85>] ret_from_fork+0x55/0x80 arch/x86/entry/entry_64.S:506
Code: b3 5f ff f6 c4 10 75 e1 44 89 e8 c1 e0 18 89 04 25 10 b3 5f ff 44 89 fa 09 da 80 cf 04 41 83 ff 02 0f 44 d3 89 14 25 00 b3 5f ff <41> f7 c4 00 02 00 00 74 1a e8 8b 20 17 00 4c 89 e7 57 9d 0f 1f