INFO: task syz-executor2:9879 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 ffff8800a6d2f8a8 29416  9879   3558 0x00000004
 ffff8800a6d2f8a8 ffff8800a6d2f858 0000000000000246 0000000000000292
 0000000041b58ab3 ffffffff83fa7300 ffff8801db31f878 ffff8801db31f8a0
 ffff8801db31ef98 ffff8800a6d3c740 ffff8800a6d3af80 ffff8800a6d28000
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-executor2/9879:
 #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: 486 Comm: khungtaskd Not tainted 4.4.107-g610c835 #12
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8800bb1f8000 task.stack: ffff8800bb2e8000
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:ffff8800bb2efcb8  EFLAGS: 00000046
RAX: 0000000003000000 RBX: 0000000000000c00 RCX: 0000000000000000
RDX: 0000000000000c00 RSI: 0000000000000000 RDI: ffffffffff5fb300
RBP: ffff8800bb2efce0 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000001 R12: 0000000000000246
R13: 0000000000000003 R14: ffffffff8426abe0 R15: 0000000000000002
FS:  0000000000000000(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f522ba8c000 CR3: 00000001da115000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 ffffffff8426abe0 ffffffff847e8600 00000000000194a0 0000000000000040
 dffffc0000000000 ffff8800bb2efd00 ffffffff810b8e1b ffffffff839f53e0
 0000000000000003 ffff8800bb2efd60 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 
NMI backtrace for cpu 1
CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.4.107-g610c835 #12
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8801da2997c0 task.stack: ffff8801da2a8000
RIP: 0010:[<ffffffff83775ea0>]  [<ffffffff83775ea0>] reschedule_interrupt+0x0/0xa0 arch/x86/entry/entry_64.S:717
RSP: 0018:ffff8801da2afd48  EFLAGS: 00000046
RAX: 0000000000000007 RBX: ffffffff847d6708 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000001 RDI: ffff8801da29a02c
RBP: ffff8801da2afd78 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000001
R13: 0000000000000000 R14: 0000000000000000 R15: dffffc0000000000
FS:  0000000000000000(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffc8606eb2c CR3: 00000001da115000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 ffffffff810cf516 0000000000000010 0000000000000246 ffff8801da2afd78
 0000000000000018 ffffffff81233c3d ffff8801da2afdb0 ffffffff81027d75
 ffff8801da2b0000 ffffffff847d6708 0000000000000000 0000000000000000
Call Trace:
 [<ffffffff81027d75>] arch_safe_halt arch/x86/include/asm/paravirt.h:117 [inline]
 [<ffffffff81027d75>] default_idle+0x55/0x3c0 arch/x86/kernel/process.c:291
 [<ffffffff810292ea>] arch_cpu_idle+0xa/0x10 arch/x86/kernel/process.c:282
 [<ffffffff8121e338>] default_idle_call+0x48/0x70 kernel/sched/idle.c:93
 [<ffffffff8121ea45>] cpuidle_idle_call kernel/sched/idle.c:157 [inline]
 [<ffffffff8121ea45>] cpu_idle_loop kernel/sched/idle.c:253 [inline]
 [<ffffffff8121ea45>] cpu_startup_entry+0x605/0x820 kernel/sched/idle.c:301
 [<ffffffff810ad2e4>] start_secondary+0x304/0x3e0 arch/x86/kernel/smpboot.c:251
Code: 01 00 65 48 0f 44 24 25 98 3e 01 00 57 e8 92 d1 88 fd e8 34 53 93 fd e9 bb e9 ff ff 0f 1f 44 00 00 66 2e 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