INFO: task syz-executor.0:2127 blocked for more than 140 seconds.
      Not tainted 4.9.171+ #49
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.0  D24648  2127      1 0x00000004
 ffff8801cf0d8000 ffff8801d42b0580 ffff8801db721000 ffff8801d7ac17c0
 ffff8801db721018 ffff8801abbe7a28 ffffffff82801dde 0000000041b58ab3
 ffffffff82e2baa0 00ffffff812003f0 ffff8801db7218f0 1ffff1003577cf34
Call Trace:
 [<0000000092ad9ce7>] schedule+0x92/0x1c0 kernel/sched/core.c:3546
 [<00000000308722aa>] schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3579
 [<00000000c7a5da09>] __mutex_lock_common kernel/locking/mutex.c:582 [inline]
 [<00000000c7a5da09>] mutex_lock_nested+0x38d/0x920 kernel/locking/mutex.c:621
 [<000000002f354eff>] lo_ioctl+0x85/0x1a10 drivers/block/loop.c:1405
 [<00000000ddcbbbbf>] __blkdev_driver_ioctl block/ioctl.c:294 [inline]
 [<00000000ddcbbbbf>] blkdev_ioctl+0xe14/0x19e0 block/ioctl.c:590
 [<0000000082c33c48>] block_ioctl+0xde/0x120 fs/block_dev.c:1696
 [<000000006bfa3f0e>] vfs_ioctl fs/ioctl.c:43 [inline]
 [<000000006bfa3f0e>] file_ioctl fs/ioctl.c:493 [inline]
 [<000000006bfa3f0e>] do_vfs_ioctl+0xb87/0x11d0 fs/ioctl.c:677
 [<00000000d3912cd3>] SYSC_ioctl fs/ioctl.c:694 [inline]
 [<00000000d3912cd3>] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:685
 [<000000003c681da0>] do_syscall_64+0x1ad/0x570 arch/x86/entry/common.c:285
 [<0000000048a3d4e7>] 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: [<00000000ee6731bf>] check_hung_uninterruptible_tasks kernel/hung_task.c:169 [inline]
 #0:  (rcu_read_lock){......}, at: [<00000000ee6731bf>] watchdog+0x14b/0xaf0 kernel/hung_task.c:263
 #1:  (tasklist_lock){.+.+..}, at: [<000000006cf808ea>] debug_show_all_locks+0x7f/0x21f kernel/locking/lockdep.c:4336
2 locks held by getty/2038:
 #0:  (&tty->ldisc_sem){++++++}, at: [<0000000058b3078d>] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:377
 #1:  (&ldata->atomic_read_lock){+.+...}, at: [<000000000f5237ea>] n_tty_read+0x1fe/0x1820 drivers/tty/n_tty.c:2156
1 lock held by syz-executor.0/2127:
 #0:  (loop_ctl_mutex/1){+.+.+.}, at: [<000000002f354eff>] lo_ioctl+0x85/0x1a10 drivers/block/loop.c:1405
2 locks held by syz-executor.4/2130:
 #0:  (&bdev->bd_mutex){+.+.+.}, at: [<00000000f5ed457c>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273
 #1:  (loop_index_mutex){+.+.+.}, at: [<0000000045671aea>] lo_open+0x1d/0xb0 drivers/block/loop.c:1622
2 locks held by syz-executor.5/2141:
 #0:  (&bdev->bd_mutex){+.+.+.}, at: [<00000000f5ed457c>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273
 #1:  (loop_index_mutex){+.+.+.}, at: [<0000000045671aea>] lo_open+0x1d/0xb0 drivers/block/loop.c:1622
2 locks held by syz-executor.2/2142:
 #0:  (&bdev->bd_mutex){+.+.+.}, at: [<00000000f5ed457c>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273
 #1:  (loop_index_mutex){+.+.+.}, at: [<0000000045671aea>] lo_open+0x1d/0xb0 drivers/block/loop.c:1622
1 lock held by syz-executor.3/2143:
 #0:  (&bdev->bd_mutex){+.+.+.}, at: [<00000000f5ed457c>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273
3 locks held by blkid/8228:
 #0:  (&bdev->bd_mutex){+.+.+.}, at: [<0000000026199f4e>] __blkdev_put+0xbb/0x840 fs/block_dev.c:1587
 #1:  (loop_index_mutex){+.+.+.}, at: [<0000000037c723f0>] lo_release+0x1e/0x1b0 drivers/block/loop.c:1664
 #2:  (loop_ctl_mutex#2){+.+.+.}, at: [<0000000068603882>] __lo_release drivers/block/loop.c:1642 [inline]
 #2:  (loop_ctl_mutex#2){+.+.+.}, at: [<0000000068603882>] lo_release+0x84/0x1b0 drivers/block/loop.c:1665
2 locks held by syz-executor.1/8231:
 #0:  (loop_ctl_mutex/1){+.+.+.}, at: [<000000002f354eff>] lo_ioctl+0x85/0x1a10 drivers/block/loop.c:1405
 #1:  (&bdev->bd_mutex){+.+.+.}, at: [<000000001752f386>] blkdev_reread_part+0x1f/0x40 block/ioctl.c:189
2 locks held by blkid/8234:
 #0:  (&bdev->bd_mutex){+.+.+.}, at: [<00000000f5ed457c>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273
 #1:  (loop_index_mutex){+.+.+.}, at: [<0000000045671aea>] lo_open+0x1d/0xb0 drivers/block/loop.c:1622

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

NMI backtrace for cpu 1
CPU: 1 PID: 24 Comm: khungtaskd Not tainted 4.9.171+ #49
 ffff8801d98d7cc8 ffffffff81b4fb61 0000000000000001 0000000000000000
 0000000000000001 ffffffff81097501 dffffc0000000000 ffff8801d98d7d00
 ffffffff81b5adfc 0000000000000001 0000000000000000 0000000000000001
Call Trace:
 [<00000000a3fd88d6>] __dump_stack lib/dump_stack.c:15 [inline]
 [<00000000a3fd88d6>] dump_stack+0xc1/0x120 lib/dump_stack.c:51
 [<00000000ec6d442e>] nmi_cpu_backtrace.cold+0x47/0x87 lib/nmi_backtrace.c:99
 [<00000000ced378ed>] nmi_trigger_cpumask_backtrace+0x124/0x155 lib/nmi_backtrace.c:60
 [<000000004ddfb6ee>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37
 [<00000000b79fd1f4>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline]
 [<00000000b79fd1f4>] check_hung_task kernel/hung_task.c:126 [inline]
 [<00000000b79fd1f4>] check_hung_uninterruptible_tasks kernel/hung_task.c:183 [inline]
 [<00000000b79fd1f4>] watchdog+0x670/0xaf0 kernel/hung_task.c:263
 [<00000000df07863f>] kthread+0x278/0x310 kernel/kthread.c:211
 [<000000007f99747d>] 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 0xffffffff82810e52