INFO: task syz-executor.3:2124 blocked for more than 140 seconds.
      Not tainted 4.4.174+ #17
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.3  D ffff8801c1db7aa8 24960  2124      1 0x20020004
 ffff8801c1db7aa8 ffff8800b8ff5f00 9ec0d4a9bf902dc8 ffff8800b8ff5f00
 0000000000000002 ffff8800b8ff6700 ffff8801db61f180 ffff8801db61f1a8
 ffff8801db61e898 ffff8800b8c55f00 ffff8800b8ff5f00 ffffed00383b6001
Call Trace:
 [<ffffffff82709b79>] schedule+0x99/0x1d0 kernel/sched/core.c:3355
 [<ffffffff8270a333>] schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3388
 [<ffffffff8270c492>] __mutex_lock_common kernel/locking/mutex.c:582 [inline]
 [<ffffffff8270c492>] mutex_lock_nested+0x3c2/0xb80 kernel/locking/mutex.c:621
 [<ffffffff81d48124>] __lo_release drivers/block/loop.c:1653 [inline]
 [<ffffffff81d48124>] lo_release+0x84/0x1b0 drivers/block/loop.c:1676
 [<ffffffff8154e4e1>] __blkdev_put+0x461/0x840 fs/block_dev.c:1535
 [<ffffffff8154f738>] blkdev_put+0x88/0x560 fs/block_dev.c:1600
 [<ffffffff8154fc9b>] blkdev_close+0x8b/0xb0 fs/block_dev.c:1607
 [<ffffffff8149c8c6>] __fput+0x246/0x710 fs/file_table.c:208
 [<ffffffff8149ce16>] ____fput+0x16/0x20 fs/file_table.c:244
 [<ffffffff8112f352>] task_work_run+0x202/0x2b0 kernel/task_work.c:115
 [<ffffffff81003dca>] tracehook_notify_resume include/linux/tracehook.h:191 [inline]
 [<ffffffff81003dca>] exit_to_usermode_loop+0x14a/0x170 arch/x86/entry/common.c:188
 [<ffffffff810064b9>] prepare_exit_to_usermode arch/x86/entry/common.c:221 [inline]
 [<ffffffff810064b9>] syscall_return_slowpath arch/x86/entry/common.c:286 [inline]
 [<ffffffff810064b9>] do_syscall_32_irqs_on arch/x86/entry/common.c:336 [inline]
 [<ffffffff810064b9>] do_fast_syscall_32+0x7a9/0xa90 arch/x86/entry/common.c:397
 [<ffffffff8271a350>] sysenter_flags_fixed+0xd/0x1a
3 locks held by syz-executor.3/2124:
 #0:  (&bdev->bd_mutex){+.+.+.}, at: [<ffffffff8154e13b>] __blkdev_put+0xbb/0x840 fs/block_dev.c:1516
 #1:  (loop_index_mutex){+.+.+.}, at: [<ffffffff81d480be>] lo_release+0x1e/0x1b0 drivers/block/loop.c:1675
 #2:  (loop_ctl_mutex#2){+.+.+.}, at: [<ffffffff81d48124>] __lo_release drivers/block/loop.c:1653 [inline]
 #2:  (loop_ctl_mutex#2){+.+.+.}, at: [<ffffffff81d48124>] lo_release+0x84/0x1b0 drivers/block/loop.c:1676
Sending NMI to all CPUs:
NMI backtrace for cpu 0
CPU: 0 PID: 20 Comm: khungtaskd Not tainted 4.4.174+ #17
task: ffff8801da6c2f80 task.stack: ffff8800001e8000
RIP: 0010:[<ffffffff8109b617>]  [<ffffffff8109b617>] _flat_send_IPI_mask arch/x86/kernel/apic/apic_flat_64.c:62 [inline]
RIP: 0010:[<ffffffff8109b617>]  [<ffffffff8109b617>] flat_send_IPI_mask+0xf7/0x1b0 arch/x86/kernel/apic/apic_flat_64.c:69
RSP: 0018:ffff8800001efc88  EFLAGS: 00000046
RAX: 0000000000000000 RBX: 0000000000000c00 RCX: 0000000000000000
RDX: 0000000000000c00 RSI: 0000000000000000 RDI: ffffffffff5fc300
RBP: ffff8800001efcb8 R08: 0000000000000018 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000001 R12: 0000000000000246
R13: 0000000003000000 R14: ffffffff82e5f2e0 R15: 0000000000000002
FS:  0000000000000000(0000) GS:ffff8801db600000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f61e5ce2000 CR3: 00000001d717d000 CR4: 00000000001606b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 0000000000000001 ffffffff82e5f2e0 ffffffff831a6ac0 fffffbfff0634c34
 000000000001b6c0 0000000000000008 ffff8800001efcd8 ffffffff81092bee
 0000000000000008 ffffffff82924260 ffff8800001efd30 ffffffff81ab8252
Call Trace:
 [<ffffffff81092bee>] nmi_raise_cpu_backtrace+0x5e/0x80 arch/x86/kernel/apic/hw_nmi.c:33
 [<ffffffff81ab8252>] nmi_trigger_all_cpu_backtrace.cold+0xa1/0xae lib/nmi_backtrace.c:85
 [<ffffffff81092ca4>] arch_trigger_all_cpu_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:38
 [<ffffffff813b4762>] trigger_all_cpu_backtrace include/linux/nmi.h:44 [inline]
 [<ffffffff813b4762>] check_hung_task kernel/hung_task.c:125 [inline]
 [<ffffffff813b4762>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline]
 [<ffffffff813b4762>] watchdog.cold+0xd3/0xee kernel/hung_task.c:238
 [<ffffffff811342c3>] kthread+0x273/0x310 kernel/kthread.c:211
 [<ffffffff82718fc5>] ret_from_fork+0x55/0x80 arch/x86/entry/entry_64.S:537
Code: 00 c3 5f ff 80 e6 10 75 e1 41 c1 e5 18 44 89 2c 25 10 c3 5f ff 44 89 fa 09 da 80 cf 04 41 83 ff 02 0f 44 d3 89 14 25 00 c3 5f ff <41> f7 c4 00 02 00 00 75 1e 4c 89 e7 57 9d 0f 1f 44 00 00 e8 f1 
NMI backtrace for cpu 1
CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.4.174+ #17
task: ffff8801da6897c0 task.stack: ffff8801da698000
RIP: 0010:[<ffffffff810a3eaf>]  [<ffffffff810a3eaf>] __pvclock_read_cycles arch/x86/include/asm/pvclock.h:92 [inline]
RIP: 0010:[<ffffffff810a3eaf>]  [<ffffffff810a3eaf>] pvclock_clocksource_read+0x28f/0x490 arch/x86/kernel/pvclock.c:84
RSP: 0018:ffff8801da69fca0  EFLAGS: 00000046
RAX: 00000105a59f448d RBX: ffff88021fffd040 RCX: 0000000000000001
RDX: 000000000000000a RSI: 0000000000000000 RDI: 0000000000000001
RBP: ffff8801da69fd28 R08: ffff88021fffd058 R09: 000000000000000a
R10: ffffed0043fffa09 R11: 0000000018d3b401 R12: dffffc0000000000
R13: ffff88021fffd043 R14: ffff88021fffd05d R15: 0000000018d3b401
FS:  0000000000000000(0000) GS:ffff8801db700000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fff6623b588 CR3: 00000001d717d000 CR4: 00000000001606b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 ffff8801da6897c0 ffffffff840036c8 0000000000000000 0000000000000000
 0000000000000002 ffff8801da69fd48 ffff88021fffd057 ffff88021fffd05b
 ffff88021fffd04f ffffed0043fffa0b ffff88021fffd05c ffff88021fffd048
Call Trace:
 [<ffffffff810a19b3>] kvm_clock_read+0x23/0x40 arch/x86/kernel/kvmclock.c:91
 [<ffffffff810a19d9>] kvm_clock_get_cycles+0x9/0x10 arch/x86/kernel/kvmclock.c:98
 [<ffffffff81272f08>] tk_clock_read kernel/time/timekeeping.c:140 [inline]
 [<ffffffff81272f08>] timekeeping_get_delta kernel/time/timekeeping.c:234 [inline]
 [<ffffffff81272f08>] timekeeping_get_ns kernel/time/timekeeping.c:340 [inline]
 [<ffffffff81272f08>] ktime_get kernel/time/timekeeping.c:756 [inline]
 [<ffffffff81272f08>] ktime_get+0xe8/0x1c0 kernel/time/timekeeping.c:744
 [<ffffffff8128c223>] tick_nohz_idle_exit+0x153/0x3d0 kernel/time/tick-sched.c:940
 [<ffffffff811ebd0a>] cpu_idle_loop kernel/sched/idle.c:267 [inline]
 [<ffffffff811ebd0a>] cpu_startup_entry+0x73a/0x810 kernel/sched/idle.c:301
 [<ffffffff8108719d>] start_secondary+0x31d/0x410 arch/x86/kernel/smpboot.c:245
Code: 84 f6 40 0f 95 c6 40 84 f2 0f 85 a8 01 00 00 8b 13 44 39 ca 0f 85 45 fe ff ff f6 c2 01 0f 85 3c fe ff ff f6 c1 02 4d 89 df 75 40 <4d> 89 fb 49 01 c3 f6 05 e4 10 10 02 01 74 05 83 e1 01 75 1a 48