INFO: task syz-executor2:12693 blocked for more than 120 seconds.
      Not tainted 4.4.107-g610c835 #12
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor2   D ffff8801ccf2f8a8 28944 12693   3538 0x00000004
 ffff8801ccf2f8a8 ffff8801ccf2f858 0000000000000246 0000000000000292
 0000000041b58ab3 ffffffff83fa7300 ffff8801db31f878 ffff8801db31f8a0
 ffff8801db31ef98 ffff8801d950c740 ffff8801d99f2f80 ffff8801ccf28000
Call Trace:
 [<ffffffff83765d3a>] schedule+0x9a/0x1c0 kernel/sched/core.c:3351
 [<ffffffff81c968a0>] blk_mq_freeze_queue_wait+0x120/0x240 block/blk-mq.c:95
 [<ffffffff81c9ee1d>] blk_freeze_queue block/blk-mq.c:112 [inline]
 [<ffffffff81c9ee1d>] blk_mq_freeze_queue+0x1d/0x20 block/blk-mq.c:121
 [<ffffffff8241bc52>] loop_set_status+0x1a2/0xfc0 drivers/block/loop.c:1112
 [<ffffffff8241cefe>] loop_set_status64+0xae/0x130 drivers/block/loop.c:1284
 [<ffffffff824200c3>] lo_ioctl+0xce3/0x19c0 drivers/block/loop.c:1374
 [<ffffffff81caca1b>] __blkdev_driver_ioctl block/ioctl.c:288 [inline]
 [<ffffffff81caca1b>] blkdev_ioctl+0x4ab/0x1990 block/ioctl.c:584
 [<ffffffff815d0c0e>] block_ioctl+0xde/0x120 fs/block_dev.c:1625
 [<ffffffff815589ba>] vfs_ioctl fs/ioctl.c:43 [inline]
 [<ffffffff815589ba>] do_vfs_ioctl+0x7aa/0xee0 fs/ioctl.c:607
 [<ffffffff8155917f>] SYSC_ioctl fs/ioctl.c:622 [inline]
 [<ffffffff8155917f>] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:613
 [<ffffffff83773d36>] entry_SYSCALL_64_fastpath+0x16/0x76
1 lock held by syz-executor2/12693:
 #0:  (&lo->lo_ctl_mutex/1){+.+.+.}, at: [<ffffffff8241f46f>] lo_ioctl+0x8f/0x19c0 drivers/block/loop.c:1348
Sending NMI to all CPUs:
NMI backtrace for cpu 0
CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.4.107-g610c835 #12
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffffffff84214840 task.stack: ffffffff84200000
RIP: 0010:[<ffffffff812d26a0>]  [<ffffffff812d26a0>] tick_nohz_restart+0x0/0x190 kernel/time/tick-sched.c:148
RSP: 0018:ffffffff84207dd0  EFLAGS: 00000046
RAX: dffffc0000000000 RBX: ffff8801db217440 RCX: ffffffff81365ed9
RDX: 1ffff1003b642e9d RSI: 0000003811990ef1 RDI: ffff8801db217440
RBP: ffffffff84207e00 R08: 1ffffffff08823c8 R09: 0000000000000001
R10: 0000000000000000 R11: dffffc0000000000 R12: ffff8801db2174b4
R13: 0000000000000001 R14: 0000003811990ef1 R15: dffffc0000000000
FS:  0000000000000000(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000001a4c800 CR3: 00000001d53a2000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 ffffffff812d4707 ffffffff84207df0 ffffffff84208000 ffffffff847d6708
 0000000000000000 0000000000000000 ffffffff84207ed0 ffffffff8121e727
 ffffffff84207e98 ffffffff84200008 ffffffff84200008 fffffbfff0840001
Call Trace:
 [<ffffffff8121e727>] cpu_idle_loop kernel/sched/idle.c:267 [inline]
 [<ffffffff8121e727>] cpu_startup_entry+0x2e7/0x820 kernel/sched/idle.c:301
 [<ffffffff83760d89>] rest_init+0x189/0x190 init/main.c:409
 [<ffffffff8481a80c>] start_kernel+0x6b4/0x6e9 init/main.c:680
 [<ffffffff84819312>] x86_64_start_reservations+0x2a/0x2c arch/x86/kernel/head64.c:196
 [<ffffffff84819454>] x86_64_start_kernel+0x140/0x163 arch/x86/kernel/head64.c:185
Code: 3c 02 00 75 11 49 83 45 00 01 e9 48 ff ff ff e8 d7 9a 22 00 eb c3 4c 89 ef e8 ed 9a 22 00 eb e5 e8 e6 9a 22 00 e9 54 ff ff ff 90 <55> 48 89 e5 41 56 49 89 f6 41 55 41 54 53 48 89 fb e8 7a b4 08 
NMI backtrace for cpu 1
CPU: 1 PID: 485 Comm: khungtaskd Not tainted 4.4.107-g610c835 #12
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8800bacb17c0 task.stack: ffff8800bb328000
RIP: 0010:[<ffffffff810c32e7>]  [<ffffffff810c32e7>] native_apic_mem_write arch/x86/include/asm/apic.h:94 [inline]
RIP: 0010:[<ffffffff810c32e7>]  [<ffffffff810c32e7>] __default_send_IPI_dest_field arch/x86/include/asm/ipi.h:119 [inline]
RIP: 0010:[<ffffffff810c32e7>]  [<ffffffff810c32e7>] _flat_send_IPI_mask arch/x86/kernel/apic/apic_flat_64.c:61 [inline]
RIP: 0010:[<ffffffff810c32e7>]  [<ffffffff810c32e7>] flat_send_IPI_mask+0xf7/0x1a0 arch/x86/kernel/apic/apic_flat_64.c:69
RSP: 0018:ffff8800bb32fcb8  EFLAGS: 00000046
RAX: 0000000003000000 RBX: 0000000000000c00 RCX: 0000000000000000
RDX: 0000000000000c00 RSI: 0000000000000000 RDI: ffffffffff5fb300
RBP: ffff8800bb32fce0 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000001 R12: 0000000000000246
R13: 0000000000000003 R14: ffffffff8426abe0 R15: 0000000000000002
FS:  0000000000000000(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000001a5d000 CR3: 00000001d53a2000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 ffffffff8426abe0 ffffffff847e8600 00000000000194a0 0000000000000040
 dffffc0000000000 ffff8800bb32fd00 ffffffff810b8e1b ffffffff839f53e0
 0000000000000003 ffff8800bb32fd60 ffffffff81d0f4d7 ffffffff81417c73
Call Trace:
 [<ffffffff810b8e1b>] nmi_raise_cpu_backtrace+0x5b/0x70 arch/x86/kernel/apic/hw_nmi.c:33
 [<ffffffff81d0f4d7>] nmi_trigger_all_cpu_backtrace+0x4a7/0x550 lib/nmi_backtrace.c:85
 [<ffffffff810b8eb4>] arch_trigger_all_cpu_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:38
 [<ffffffff81365a7a>] trigger_all_cpu_backtrace include/linux/nmi.h:44 [inline]
 [<ffffffff81365a7a>] check_hung_task kernel/hung_task.c:125 [inline]
 [<ffffffff81365a7a>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline]
 [<ffffffff81365a7a>] watchdog+0x6fa/0xae0 kernel/hung_task.c:238
 [<ffffffff8118dea8>] kthread+0x268/0x300 kernel/kthread.c:211
 [<ffffffff837740ef>] ret_from_fork+0x3f/0x70 arch/x86/entry/entry_64.S:468
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 3b 09 17 00 4c 89 e7 57 9d 0f 1f