INFO: task syz-executor0:6595 blocked for more than 120 seconds.
      Not tainted 4.9.103-g0cecdf8 #38
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor0   D29512  6595   3864 0x00000004
 ffff8801c9df8000 ffff8801bb895a40 ffff8801bbb94fc0 ffff8801ca776000
 ffff8801db221c18 ffff88019a137820 ffffffff839e711d 0000000000000002
 0000000041b58ab3 ffffffff843b9803 00ffffff81221330 ffff8801db2224e8
Call Trace:
 [<ffffffff839e871f>] schedule+0x7f/0x1b0 kernel/sched/core.c:3557
 [<ffffffff81e40ba4>] blk_mq_freeze_queue_wait+0x114/0x230 block/blk-mq.c:75
 [<ffffffff81e49e9d>] blk_freeze_queue block/blk-mq.c:92 [inline]
 [<ffffffff81e49e9d>] blk_mq_freeze_queue+0x1d/0x20 block/blk-mq.c:101
 [<ffffffff825c65c5>] loop_set_status+0x1b5/0xfe0 drivers/block/loop.c:1104
 [<ffffffff825c788f>] loop_set_status64+0xbf/0x110 drivers/block/loop.c:1280
 [<ffffffff825ca096>] lo_ioctl+0x406/0x1aa0 drivers/block/loop.c:1370
 [<ffffffff81e570a6>] __blkdev_driver_ioctl block/ioctl.c:294 [inline]
 [<ffffffff81e570a6>] blkdev_ioctl+0x7b6/0x1a70 block/ioctl.c:590
 [<ffffffff8163259e>] block_ioctl+0xde/0x120 fs/block_dev.c:1688
 [<ffffffff815b27cc>] vfs_ioctl fs/ioctl.c:43 [inline]
 [<ffffffff815b27cc>] file_ioctl fs/ioctl.c:493 [inline]
 [<ffffffff815b27cc>] do_vfs_ioctl+0x1ac/0x11a0 fs/ioctl.c:677
 [<ffffffff815b384f>] SYSC_ioctl fs/ioctl.c:694 [inline]
 [<ffffffff815b384f>] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:685
 [<ffffffff81006316>] do_syscall_64+0x1a6/0x490 arch/x86/entry/common.c:282
 [<ffffffff839f8013>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb

Showing all locks held in the system:
2 locks held by khungtaskd/519:
 #0:  (rcu_read_lock){......}, at: [<ffffffff8136688c>] check_hung_uninterruptible_tasks kernel/hung_task.c:168 [inline]
 #0:  (rcu_read_lock){......}, at: [<ffffffff8136688c>] watchdog+0x11c/0xa20 kernel/hung_task.c:239
 #1:  (tasklist_lock){.+.+..}, at: [<ffffffff81425e10>] debug_show_all_locks+0x79/0x218 kernel/locking/lockdep.c:4336
1 lock held by rsyslogd/3681:
 #0:  (&f->f_pos_lock){+.+.+.}, at: [<ffffffff815d7a4c>] __fdget_pos+0xac/0xd0 fs/file.c:781
2 locks held by getty/3777:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff839f61c2>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+...}, at: [<ffffffff8211f1d2>] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2133
1 lock held by syz-executor0/6595:
 #0:  (&lo->lo_ctl_mutex/1){+.+.+.}, at: [<ffffffff825c9d1b>] lo_ioctl+0x8b/0x1aa0 drivers/block/loop.c:1344
1 lock held by syz-executor0/6653:
 #0:  (&lo->lo_ctl_mutex/1){+.+.+.}, at: [<ffffffff825c9d1b>] lo_ioctl+0x8b/0x1aa0 drivers/block/loop.c:1344
1 lock held by syz-executor0/6655:
 #0:  (&lo->lo_ctl_mutex/1){+.+.+.}, at: [<ffffffff825c9d1b>] lo_ioctl+0x8b/0x1aa0 drivers/block/loop.c:1344

=============================================

NMI backtrace for cpu 0
CPU: 0 PID: 519 Comm: khungtaskd Not tainted 4.9.103-g0cecdf8 #38
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801d85a7d08 ffffffff81eb34a9 0000000000000000 0000000000000000
 0000000000000000 0000000000000001 ffffffff810b9590 ffff8801d85a7d40
 ffffffff81ebe7a7 0000000000000000 0000000000000000 0000000000000003
Call Trace:
 [<ffffffff81eb34a9>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81eb34a9>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff81ebe7a7>] nmi_cpu_backtrace.cold.2+0x48/0x87 lib/nmi_backtrace.c:99
 [<ffffffff81ebe73a>] nmi_trigger_cpumask_backtrace+0x12a/0x14f lib/nmi_backtrace.c:60
 [<ffffffff810b9694>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37
 [<ffffffff81366e24>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline]
 [<ffffffff81366e24>] check_hung_task kernel/hung_task.c:125 [inline]
 [<ffffffff81366e24>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline]
 [<ffffffff81366e24>] watchdog+0x6b4/0xa20 kernel/hung_task.c:239
 [<ffffffff8119cead>] kthread+0x26d/0x300 kernel/kthread.c:211
 [<ffffffff839f81dc>] ret_from_fork+0x5c/0x70 arch/x86/entry/entry_64.S:373
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.9.103-g0cecdf8 #38
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8801d9a6b000 task.stack: ffff8801d9a80000
RIP: 0010:[<ffffffff839fa270>] 
c [<ffffffff839fa270>] reschedule_interrupt+0x0/0xb0 arch/x86/entry/entry_64.S:670
RSP: 0018:ffff8801d9a87d68  EFLAGS: 00000046
RAX: 0000000000000007 RBX: ffffffff84c4e1c8 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000001 RDI: ffff8801d9a6b8c4
RBP: ffff8801d9a87d98 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000001 R14: ffffffff84c5e308 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f8532758000 CR3: 00000001d387c000 CR4: 00000000001606f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 ffffffff839f6c26
c 0000000000000010
c 0000000000000246
c ffff8801d9a87d98
c
 0000000000000018
c ffffffff81235f6d
c ffff8801d9a87dd0
c ffffffff839f6265
c
 ffff8801d9a6b000
c 0000000000000000
c dffffc0000000000
c ffffffff84c5e308
c
Call Trace:
 [<ffffffff839f6265>] arch_safe_halt arch/x86/include/asm/paravirt.h:104 [inline]
 [<ffffffff839f6265>] default_idle+0x55/0x360 arch/x86/kernel/process.c:437
 [<ffffffff8106ab20>] arch_cpu_idle+0x10/0x20 arch/x86/kernel/process.c:428
 [<ffffffff839f7085>] default_idle_call+0x45/0x60 kernel/sched/idle.c:97
 [<ffffffff81222fb5>] cpuidle_idle_call kernel/sched/idle.c:155 [inline]
 [<ffffffff81222fb5>] cpu_idle_loop kernel/sched/idle.c:248 [inline]
 [<ffffffff81222fb5>] cpu_startup_entry+0x2b5/0x380 kernel/sched/idle.c:303
 [<ffffffff810ae9e8>] start_secondary+0x328/0x400 arch/x86/kernel/smpboot.c:257
Code: 
c04 
c25 
c54 
c7d 
c01 
c00 
c65 
c48 
c0f 
c44 
c24 
c25 
c58 
c7d 
c01 
c00 
c57 
ce8 
cc1 
c8d 
c60 
cfd 
ce8 
cf0 
c2a 
c00 
c00 
ce9 
cbb 
ce6 
cff 
cff 
c90 
c66 
c2e 
c0f 
c1f 
c84 
c00 
c00 
c00 
c00 
c00 
c<0f> 
c1f 
c00 
c68 
c02 
cff 
cff 
cff 
cfc 
c48 
c83 
cc4 
c88 
c4c 
c89 
c5c 
c24 
c30 
c4c 
c89 
c54 
c