INFO: task syz-executor.3:2128 blocked for more than 140 seconds.
      Not tainted 4.9.170+ #45
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.3  D25528  2128      1 0x00000004
 ffff8801d070df00 ffff8801d2eb1080 ffff8801db621000 ffff8801cc1b5f00
 ffff8801db621018 ffff8801ad3efa28 ffffffff8280185e ffffffff82e2bb28
 ffffffff81208040 0000000200000000 ffff8801db6218f0 1ffff10035a7df34
Call Trace:
 [<00000000aa1256cf>] schedule+0x92/0x1c0 kernel/sched/core.c:3546
 [<00000000c92b8452>] schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3579
 [<000000006195358f>] __mutex_lock_common kernel/locking/mutex.c:582 [inline]
 [<000000006195358f>] mutex_lock_nested+0x38d/0x920 kernel/locking/mutex.c:621
 [<00000000647790fd>] lo_ioctl+0x85/0x1a10 drivers/block/loop.c:1405
 [<00000000646037c2>] __blkdev_driver_ioctl block/ioctl.c:294 [inline]
 [<00000000646037c2>] blkdev_ioctl+0xe14/0x19e0 block/ioctl.c:590
 [<000000004fc76d2a>] block_ioctl+0xde/0x120 fs/block_dev.c:1696
 [<00000000b055403e>] vfs_ioctl fs/ioctl.c:43 [inline]
 [<00000000b055403e>] file_ioctl fs/ioctl.c:493 [inline]
 [<00000000b055403e>] do_vfs_ioctl+0xb87/0x11d0 fs/ioctl.c:677
 [<0000000075a6617c>] SYSC_ioctl fs/ioctl.c:694 [inline]
 [<0000000075a6617c>] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:685
 [<000000007d609519>] do_syscall_64+0x1ad/0x570 arch/x86/entry/common.c:285
 [<000000004370a53b>] 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: [<00000000ca43c104>] check_hung_uninterruptible_tasks kernel/hung_task.c:169 [inline]
 #0:  (rcu_read_lock){......}, at: [<00000000ca43c104>] watchdog+0x14b/0xaf0 kernel/hung_task.c:263
 #1:  (tasklist_lock){.+.+..}, at: [<000000003fc311a8>] debug_show_all_locks+0x7f/0x21f kernel/locking/lockdep.c:4339
2 locks held by getty/2038:
 #0:  (&tty->ldisc_sem){++++++}, at: [<00000000a9a1bbd8>] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:377
 #1:  (&ldata->atomic_read_lock){+.+...}, at: [<00000000961f61ef>] n_tty_read+0x1fe/0x1820 drivers/tty/n_tty.c:2156
1 lock held by syz-executor.3/2128:
 #0:  (loop_ctl_mutex/1){+.+.+.}, at: [<00000000647790fd>] lo_ioctl+0x85/0x1a10 drivers/block/loop.c:1405
2 locks held by syz-executor.4/2133:
 #0:  (&bdev->bd_mutex){+.+.+.}, at: [<000000000a879a62>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273
 #1:  (loop_index_mutex){+.+.+.}, at: [<00000000e7d817c9>] lo_open+0x1d/0xb0 drivers/block/loop.c:1622
1 lock held by syz-executor.5/2139:
 #0:  (&bdev->bd_mutex){+.+.+.}, at: [<000000000a879a62>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273
2 locks held by syz-executor.1/2149:
 #0:  (&bdev->bd_mutex){+.+.+.}, at: [<000000000a879a62>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273
 #1:  (loop_index_mutex){+.+.+.}, at: [<00000000e7d817c9>] lo_open+0x1d/0xb0 drivers/block/loop.c:1622
2 locks held by syz-executor.0/3758:
 #0:  (&bdev->bd_mutex){+.+.+.}, at: [<000000000a879a62>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273
 #1:  (loop_index_mutex){+.+.+.}, at: [<00000000e7d817c9>] lo_open+0x1d/0xb0 drivers/block/loop.c:1622
2 locks held by syz-executor.2/11901:
 #0:  (loop_ctl_mutex/1){+.+.+.}, at: [<00000000647790fd>] lo_ioctl+0x85/0x1a10 drivers/block/loop.c:1405
 #1:  (&bdev->bd_mutex){+.+.+.}, at: [<0000000018322141>] blkdev_reread_part+0x1f/0x40 block/ioctl.c:189
1 lock held by syz-executor.2/11916:
 #0:  (&bdev->bd_mutex){+.+.+.}, at: [<000000000a879a62>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273
3 locks held by blkid/11900:
 #0:  (&bdev->bd_mutex){+.+.+.}, at: [<0000000004d9a2d9>] __blkdev_put+0xbb/0x840 fs/block_dev.c:1587
 #1:  (loop_index_mutex){+.+.+.}, at: [<000000003f98676c>] lo_release+0x1e/0x1b0 drivers/block/loop.c:1664
 #2:  (loop_ctl_mutex#2){+.+.+.}, at: [<0000000092218ee1>] __lo_release drivers/block/loop.c:1642 [inline]
 #2:  (loop_ctl_mutex#2){+.+.+.}, at: [<0000000092218ee1>] lo_release+0x84/0x1b0 drivers/block/loop.c:1665
2 locks held by blkid/11908:
 #0:  (&bdev->bd_mutex){+.+.+.}, at: [<000000000a879a62>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273
 #1:  (loop_index_mutex){+.+.+.}, at: [<00000000e7d817c9>] lo_open+0x1d/0xb0 drivers/block/loop.c:1622

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

NMI backtrace for cpu 0
CPU: 0 PID: 24 Comm: khungtaskd Not tainted 4.9.170+ #45
 ffff8801d98d7cc8 ffffffff81b4fb21 0000000000000000 0000000000000000
 0000000000000000 ffffffff81097401 dffffc0000000000 ffff8801d98d7d00
 ffffffff81b5adbc 0000000000000000 0000000000000000 0000000000000000
Call Trace:
 [<000000007fc8e236>] __dump_stack lib/dump_stack.c:15 [inline]
 [<000000007fc8e236>] dump_stack+0xc1/0x120 lib/dump_stack.c:51
 [<00000000c44bfff4>] nmi_cpu_backtrace.cold+0x47/0x87 lib/nmi_backtrace.c:99
 [<000000006e0af315>] nmi_trigger_cpumask_backtrace+0x124/0x155 lib/nmi_backtrace.c:60
 [<00000000295dd39e>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37
 [<000000007f864611>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline]
 [<000000007f864611>] check_hung_task kernel/hung_task.c:126 [inline]
 [<000000007f864611>] check_hung_uninterruptible_tasks kernel/hung_task.c:183 [inline]
 [<000000007f864611>] watchdog+0x670/0xaf0 kernel/hung_task.c:263
 [<0000000071f9705f>] kthread+0x278/0x310 kernel/kthread.c:211
 [<00000000c2296bc7>] 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 skipped: idling at pc 0xffffffff828108d2