INFO: task syz-executor.0:2106 blocked for more than 140 seconds.
      Not tainted 4.9.169+ #43
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.0  D25528  2106      1 0x00000004
 ffff8801d1fd4740 ffff8801d16e5d80 ffff8801db721000 ffff8801d71eaf80
 ffff8801db721018 ffff8801a941fa28 ffffffff8280152e 0000000041b58ab3
 ffffffff82e2b8b0 00ffffff81200360 ffff8801db7218f0 1ffff10035283f34
Call Trace:
 [<000000006f151792>] schedule+0x92/0x1c0 kernel/sched/core.c:3546
 [<00000000b1f6b46c>] schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3579
 [<000000009a2a4898>] __mutex_lock_common kernel/locking/mutex.c:582 [inline]
 [<000000009a2a4898>] mutex_lock_nested+0x38d/0x920 kernel/locking/mutex.c:621
 [<00000000953426a4>] lo_ioctl+0x85/0x1a10 drivers/block/loop.c:1405
 [<000000008062c495>] __blkdev_driver_ioctl block/ioctl.c:294 [inline]
 [<000000008062c495>] blkdev_ioctl+0xe14/0x19e0 block/ioctl.c:590
 [<00000000f60ab35b>] block_ioctl+0xde/0x120 fs/block_dev.c:1696
 [<00000000b324917e>] vfs_ioctl fs/ioctl.c:43 [inline]
 [<00000000b324917e>] file_ioctl fs/ioctl.c:493 [inline]
 [<00000000b324917e>] do_vfs_ioctl+0xb87/0x11d0 fs/ioctl.c:677
 [<00000000bc456614>] SYSC_ioctl fs/ioctl.c:694 [inline]
 [<00000000bc456614>] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:685
 [<000000003a85f5b9>] do_syscall_64+0x1ad/0x570 arch/x86/entry/common.c:285
 [<00000000746b7212>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb

Showing all locks held in the system:
2 locks held by khungtaskd/24:
 #0:  (rcu_read_lock){......}, at: [<00000000a3cad110>] check_hung_uninterruptible_tasks kernel/hung_task.c:168 [inline]
 #0:  (rcu_read_lock){......}, at: [<00000000a3cad110>] watchdog+0x13c/0xae0 kernel/hung_task.c:239
 #1:  (tasklist_lock){.+.+..}, at: [<0000000084c57697>] debug_show_all_locks+0x7f/0x21f kernel/locking/lockdep.c:4339
2 locks held by getty/2016:
 #0:  (&tty->ldisc_sem){++++++}, at: [<00000000323c428d>] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:377
 #1:  (&ldata->atomic_read_lock){+.+...}, at: [<00000000c93e6d0d>] n_tty_read+0x1fe/0x1820 drivers/tty/n_tty.c:2156
1 lock held by syz-executor.0/2106:
 #0:  (loop_ctl_mutex/1){+.+.+.}, at: [<00000000953426a4>] lo_ioctl+0x85/0x1a10 drivers/block/loop.c:1405
2 locks held by syz-executor.4/4253:
 #0:  (&bdev->bd_mutex){+.+.+.}, at: [<000000009655a16d>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273
 #1:  (loop_index_mutex){+.+.+.}, at: [<00000000e896dd9b>] lo_open+0x1d/0xb0 drivers/block/loop.c:1622
3 locks held by syz-executor.1/15004:
 #0:  (&bdev->bd_mutex){+.+.+.}, at: [<000000002022c8d0>] __blkdev_put+0xbb/0x840 fs/block_dev.c:1587
 #1:  (loop_index_mutex){+.+.+.}, at: [<0000000076bd689e>] lo_release+0x1e/0x1b0 drivers/block/loop.c:1664
 #2:  (loop_ctl_mutex#2){+.+.+.}, at: [<000000007476dd6e>] __lo_release drivers/block/loop.c:1642 [inline]
 #2:  (loop_ctl_mutex#2){+.+.+.}, at: [<000000007476dd6e>] lo_release+0x84/0x1b0 drivers/block/loop.c:1665
2 locks held by syz-executor.3/15001:
 #0:  (loop_ctl_mutex/1){+.+.+.}, at: [<00000000953426a4>] lo_ioctl+0x85/0x1a10 drivers/block/loop.c:1405
 #1:  (&bdev->bd_mutex){+.+.+.}, at: [<00000000e6cf671e>] blkdev_reread_part+0x1f/0x40 block/ioctl.c:189
1 lock held by syz-executor.3/15035:
 #0:  (&bdev->bd_mutex){+.+.+.}, at: [<000000009655a16d>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273
1 lock held by blkid/15024:
 #0:  (&bdev->bd_mutex){+.+.+.}, at: [<000000009655a16d>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273
2 locks held by blkid/15025:
 #0:  (&bdev->bd_mutex){+.+.+.}, at: [<000000009655a16d>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273
 #1:  (loop_index_mutex){+.+.+.}, at: [<00000000e896dd9b>] lo_open+0x1d/0xb0 drivers/block/loop.c:1622

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

NMI backtrace for cpu 1
CPU: 1 PID: 24 Comm: khungtaskd Not tainted 4.9.169+ #43
 ffff8801d98d7cc8 ffffffff81b4f7f1 0000000000000001 0000000000000000
 0000000000000001 ffffffff81097401 dffffc0000000000 ffff8801d98d7d00
 ffffffff81b5aa8c 0000000000000001 0000000000000000 0000000000000001
Call Trace:
 [<00000000a9fc8cf2>] __dump_stack lib/dump_stack.c:15 [inline]
 [<00000000a9fc8cf2>] dump_stack+0xc1/0x120 lib/dump_stack.c:51
 [<000000009ae5524b>] nmi_cpu_backtrace.cold+0x47/0x87 lib/nmi_backtrace.c:99
 [<000000006811e240>] nmi_trigger_cpumask_backtrace+0x124/0x155 lib/nmi_backtrace.c:60
 [<00000000587219b7>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37
 [<00000000f7220b78>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline]
 [<00000000f7220b78>] check_hung_task kernel/hung_task.c:125 [inline]
 [<00000000f7220b78>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline]
 [<00000000f7220b78>] watchdog+0x661/0xae0 kernel/hung_task.c:239
 [<00000000bebeadfd>] kthread+0x278/0x310 kernel/kthread.c:211
 [<000000000de42fa4>] ret_from_fork+0x5c/0x70 arch/x86/entry/entry_64.S:373
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0 skipped: idling at pc 0xffffffff828105a2