INFO: task syz-executor7:9770 blocked for more than 120 seconds.
      Not tainted 4.4.110-gdac1439 #13
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor7   D ffff8801d1c67890 28536  9770   3565 0x20020004
 ffff8801d1c67890 ffff8801d1c67840 0000000000000246 0000000000000286
 0000000041b58ab3 ffffffff83fa8300 ffff8801db31fdb8 ffff8801db31fde0
 ffff8801db31f4d8 ffff8801d4f40000 ffff8800b582af80 ffff8801d1c60000
Call Trace:
 [<ffffffff837675ba>] schedule+0x9a/0x1c0 kernel/sched/core.c:3351
 [<ffffffff81c97160>] blk_mq_freeze_queue_wait+0x120/0x240 block/blk-mq.c:95
 [<ffffffff81c9f6dd>] blk_freeze_queue block/blk-mq.c:112 [inline]
 [<ffffffff81c9f6dd>] blk_mq_freeze_queue+0x1d/0x20 block/blk-mq.c:121
 [<ffffffff8241cbe2>] loop_set_status+0x1a2/0xfc0 drivers/block/loop.c:1112
 [<ffffffff8241da9a>] loop_set_status_compat+0x9a/0x100 drivers/block/loop.c:1499
 [<ffffffff82421e44>] lo_compat_ioctl+0x114/0x140 drivers/block/loop.c:1527
 [<ffffffff81cf8e64>] compat_blkdev_ioctl+0x3d4/0x3b10 block/compat_ioctl.c:751
 [<ffffffff8161de7a>] C_SYSC_ioctl fs/compat_ioctl.c:1592 [inline]
 [<ffffffff8161de7a>] compat_SyS_ioctl+0x28a/0x2540 fs/compat_ioctl.c:1544
 [<ffffffff81006d84>] do_syscall_32_irqs_on arch/x86/entry/common.c:390 [inline]
 [<ffffffff81006d84>] do_fast_syscall_32+0x314/0x890 arch/x86/entry/common.c:457
 [<ffffffff83776f6a>] sysenter_flags_fixed+0xd/0x17
1 lock held by syz-executor7/9770:
 #0:  (&lo->lo_ctl_mutex#2){+.+.+.}, at: [<ffffffff82421e39>] lo_compat_ioctl+0x109/0x140 drivers/block/loop.c:1526
Sending NMI to all CPUs:
NMI backtrace for cpu 0
CPU: 0 PID: 485 Comm: khungtaskd Not tainted 4.4.110-gdac1439 #13
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8800bac0af80 task.stack: ffff8800bb0e0000
RIP: 0010:[<ffffffff810c39c7>]  [<ffffffff810c39c7>] native_apic_mem_write arch/x86/include/asm/apic.h:94 [inline]
RIP: 0010:[<ffffffff810c39c7>]  [<ffffffff810c39c7>] __default_send_IPI_dest_field arch/x86/include/asm/ipi.h:119 [inline]
RIP: 0010:[<ffffffff810c39c7>]  [<ffffffff810c39c7>] _flat_send_IPI_mask arch/x86/kernel/apic/apic_flat_64.c:61 [inline]
RIP: 0010:[<ffffffff810c39c7>]  [<ffffffff810c39c7>] flat_send_IPI_mask+0xf7/0x1a0 arch/x86/kernel/apic/apic_flat_64.c:69
RSP: 0018:ffff8800bb0e7cb8  EFLAGS: 00000046
RAX: 0000000003000000 RBX: 0000000000000c00 RCX: 0000000000000000
RDX: 0000000000000c00 RSI: 0000000000000000 RDI: ffffffffff5fb300
RBP: ffff8800bb0e7ce0 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000001 R12: 0000000000000246
R13: 0000000000000003 R14: ffffffff8426ea20 R15: 0000000000000002
FS:  0000000000000000(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f5f06697140 CR3: 00000001d392e000 CR4: 0000000000160670
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 ffffffff8426ea20 ffffffff847ee1c0 000000000001bca0 0000000000000040
 dffffc0000000000 ffff8800bb0e7d00 ffffffff810b94fb ffffffff839f56a0
 0000000000000003 ffff8800bb0e7d60 ffffffff81d0fd97 ffffffff81419d23
Call Trace:
 [<ffffffff810b94fb>] nmi_raise_cpu_backtrace+0x5b/0x70 arch/x86/kernel/apic/hw_nmi.c:33
 [<ffffffff81d0fd97>] nmi_trigger_all_cpu_backtrace+0x4a7/0x550 lib/nmi_backtrace.c:85
 [<ffffffff810b9594>] arch_trigger_all_cpu_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:38
 [<ffffffff81367b8a>] trigger_all_cpu_backtrace include/linux/nmi.h:44 [inline]
 [<ffffffff81367b8a>] check_hung_task kernel/hung_task.c:125 [inline]
 [<ffffffff81367b8a>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline]
 [<ffffffff81367b8a>] watchdog+0x6fa/0xae0 kernel/hung_task.c:238
 [<ffffffff81190818>] kthread+0x268/0x300 kernel/kthread.c:211
 [<ffffffff837759df>] ret_from_fork+0x3f/0x70 arch/x86/entry/entry_64.S:494
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 5b 23 17 00 4c 89 e7 57 9d 0f 1f 
NMI backtrace for cpu 1
CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.4.110-gdac1439 #13
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8801da3a17c0 task.stack: ffff8801da3b0000
RIP: 0010:[<ffffffff810d0526>]  [<ffffffff810d0526>] native_safe_halt+0x6/0x10 arch/x86/include/asm/irqflags.h:49
RSP: 0018:ffff8801da3b7d78  EFLAGS: 00000246
RAX: 0000000000000007 RBX: ffffffff847dc2c8 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000001 RDI: ffff8801da3a202c
RBP: ffff8801da3b7d78 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: ffffffffff600400 CR3: 00000001d392e000 CR4: 0000000000160670
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 ffff8801da3b7db0 ffffffff81027e15 ffff8801da3b8000 ffffffff847dc2c8
 0000000000000000 0000000000000000 dffffc0000000000 ffff8801da3b7dc0
 ffffffff8102938a ffff8801da3b7dd8 ffffffff81220438 ffff8801da3b8000
Call Trace:
 [<ffffffff81027e15>] arch_safe_halt arch/x86/include/asm/paravirt.h:117 [inline]
 [<ffffffff81027e15>] default_idle+0x55/0x3c0 arch/x86/kernel/process.c:291
 [<ffffffff8102938a>] arch_cpu_idle+0xa/0x10 arch/x86/kernel/process.c:282
 [<ffffffff81220438>] default_idle_call+0x48/0x70 kernel/sched/idle.c:93
 [<ffffffff81220b45>] cpuidle_idle_call kernel/sched/idle.c:157 [inline]
 [<ffffffff81220b45>] cpu_idle_loop kernel/sched/idle.c:253 [inline]
 [<ffffffff81220b45>] cpu_startup_entry+0x605/0x820 kernel/sched/idle.c:301
 [<ffffffff810ad7a4>] start_secondary+0x304/0x3e0 arch/x86/kernel/smpboot.c:242
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