INFO: task syz-executor874:3914 blocked for more than 120 seconds.
      Not tainted 4.9.108-gb7d377b #47
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor874 D28232  3914   3911 0x00000000
 ffff8801d6d78000 0000000000000000 ffff8801d6e25a40 ffff8801d9a6b000
 ffff8801db321c18 ffff8801b654f9c8 ffffffff839e8aed ffff8801d6d788c8
 ffffed003adaf118 ffff8801d6d78000 00fffc0000000000 ffff8801db3224e8
Call Trace:
 [<ffffffff839ea0ef>] schedule+0x7f/0x1b0 kernel/sched/core.c:3557
 [<ffffffff839eaa73>] schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3590
 [<ffffffff839eeef6>] __mutex_lock_common kernel/locking/mutex.c:582 [inline]
 [<ffffffff839eeef6>] mutex_lock_nested+0x326/0x870 kernel/locking/mutex.c:621
 [<ffffffff825ca87b>] lo_ioctl+0x8b/0x1aa0 drivers/block/loop.c:1344
 [<ffffffff81e57a26>] __blkdev_driver_ioctl block/ioctl.c:294 [inline]
 [<ffffffff81e57a26>] blkdev_ioctl+0x7b6/0x1a70 block/ioctl.c:590
 [<ffffffff81632b8e>] block_ioctl+0xde/0x120 fs/block_dev.c:1688
 [<ffffffff815b2b9c>] vfs_ioctl fs/ioctl.c:43 [inline]
 [<ffffffff815b2b9c>] file_ioctl fs/ioctl.c:493 [inline]
 [<ffffffff815b2b9c>] do_vfs_ioctl+0x1ac/0x11a0 fs/ioctl.c:677
 [<ffffffff815b3c1f>] SYSC_ioctl fs/ioctl.c:694 [inline]
 [<ffffffff815b3c1f>] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:685
 [<ffffffff81006316>] do_syscall_64+0x1a6/0x490 arch/x86/entry/common.c:282
 [<ffffffff839f99d3>] 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: [<ffffffff8136662c>] check_hung_uninterruptible_tasks kernel/hung_task.c:168 [inline]
 #0:  (rcu_read_lock){......}, at: [<ffffffff8136662c>] watchdog+0x11c/0xa20 kernel/hung_task.c:239
 #1:  (tasklist_lock){.+.+..}, at: [<ffffffff81425cb7>] debug_show_all_locks+0x79/0x218 kernel/locking/lockdep.c:4336
2 locks held by getty/3776:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff839f7b92>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+...}, at: [<ffffffff8211fce2>] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2133
1 lock held by syz-executor874/3914:
 #0:  (&lo->lo_ctl_mutex/1){+.+.+.}, at: [<ffffffff825ca87b>] lo_ioctl+0x8b/0x1aa0 drivers/block/loop.c:1344
1 lock held by syz-executor874/3916:
 #0:  (&lo->lo_ctl_mutex/1){+.+.+.}, at: [<ffffffff825ca87b>] lo_ioctl+0x8b/0x1aa0 drivers/block/loop.c:1344
1 lock held by syz-executor874/3917:
 #0:  (&lo->lo_ctl_mutex/1){+.+.+.}, at: [<ffffffff825ca87b>] lo_ioctl+0x8b/0x1aa0 drivers/block/loop.c:1344
1 lock held by syz-executor874/3919:
 #0:  (&lo->lo_ctl_mutex/1){+.+.+.}, at: [<ffffffff825ca87b>] lo_ioctl+0x8b/0x1aa0 drivers/block/loop.c:1344
1 lock held by syz-executor874/3920:
 #0:  (&lo->lo_ctl_mutex/1){+.+.+.}, at: [<ffffffff825ca87b>] lo_ioctl+0x8b/0x1aa0 drivers/block/loop.c:1344
1 lock held by syz-executor874/3921:
 #0:  (&lo->lo_ctl_mutex/1){+.+.+.}, at: [<ffffffff825ca87b>] lo_ioctl+0x8b/0x1aa0 drivers/block/loop.c:1344
1 lock held by syz-executor874/3922:
 #0:  (&lo->lo_ctl_mutex/1){+.+.+.}, at: [<ffffffff825ca87b>] lo_ioctl+0x8b/0x1aa0 drivers/block/loop.c:1344
1 lock held by syz-executor874/3923:
 #0:  (&lo->lo_ctl_mutex/1){+.+.+.}, at: [<ffffffff825ca87b>] lo_ioctl+0x8b/0x1aa0 drivers/block/loop.c:1344
1 lock held by syz-executor874/3924:
 #0:  (&lo->lo_ctl_mutex/1){+.+.+.}, at: [<ffffffff825ca87b>] lo_ioctl+0x8b/0x1aa0 drivers/block/loop.c:1344
1 lock held by syz-executor874/3926:
 #0:  (&lo->lo_ctl_mutex/1){+.+.+.}, at: [<ffffffff825ca87b>] lo_ioctl+0x8b/0x1aa0 drivers/block/loop.c:1344
1 lock held by syz-executor874/3927:
 #0:  (&lo->lo_ctl_mutex/1){+.+.+.}, at: [<ffffffff825ca87b>] lo_ioctl+0x8b/0x1aa0 drivers/block/loop.c:1344
1 lock held by syz-executor874/3928:
 #0:  (&lo->lo_ctl_mutex/1){+.+.+.}, at: [<ffffffff825ca87b>] lo_ioctl+0x8b/0x1aa0 drivers/block/loop.c:1344
1 lock held by syz-executor874/3929:
 #0:  (&lo->lo_ctl_mutex/1){+.+.+.}, at: [<ffffffff825ca87b>] lo_ioctl+0x8b/0x1aa0 drivers/block/loop.c:1344
1 lock held by syz-executor874/3930:
 #0:  (&lo->lo_ctl_mutex/1){+.+.+.}, at: [<ffffffff825ca87b>] lo_ioctl+0x8b/0x1aa0 drivers/block/loop.c:1344
1 lock held by syz-executor874/3932:
 #0:  (&lo->lo_ctl_mutex/1){+.+.+.}, at: [<ffffffff825ca87b>] lo_ioctl+0x8b/0x1aa0 drivers/block/loop.c:1344
1 lock held by syz-executor874/3933:
 #0:  (&lo->lo_ctl_mutex/1){+.+.+.}, at: [<ffffffff825ca87b>] lo_ioctl+0x8b/0x1aa0 drivers/block/loop.c:1344
1 lock held by blkid/3934:
 #0:  (&lo->lo_ctl_mutex/1){+.+.+.}, at: [<ffffffff825ca87b>] lo_ioctl+0x8b/0x1aa0 drivers/block/loop.c:1344

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

NMI backtrace for cpu 1
CPU: 1 PID: 519 Comm: khungtaskd Not tainted 4.9.108-gb7d377b #47
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801d8607d08 ffffffff81eb3e29 0000000000000000 0000000000000001
 0000000000000001 0000000000000001 ffffffff810b96a0 ffff8801d8607d40
 ffffffff81ebf127 0000000000000001 0000000000000000 0000000000000003
Call Trace:
 [<ffffffff81eb3e29>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81eb3e29>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff81ebf127>] nmi_cpu_backtrace.cold.2+0x48/0x87 lib/nmi_backtrace.c:99
 [<ffffffff81ebf0ba>] nmi_trigger_cpumask_backtrace+0x12a/0x14f lib/nmi_backtrace.c:60
 [<ffffffff810b97a4>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37
 [<ffffffff81366bc4>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline]
 [<ffffffff81366bc4>] check_hung_task kernel/hung_task.c:125 [inline]
 [<ffffffff81366bc4>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline]
 [<ffffffff81366bc4>] watchdog+0x6b4/0xa20 kernel/hung_task.c:239
 [<ffffffff8119d04d>] kthread+0x26d/0x300 kernel/kthread.c:211
 [<ffffffff839f9b9c>] 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
CPU: 0 PID: 3913 Comm: syz-executor874 Not tainted 4.9.108-gb7d377b #47
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8801d6834800 task.stack: ffff8801d6120000
RIP: 0033:[<0000000000400a06>] 
c [<0000000000400a06>] 0x400a06
RSP: 002b:00007ffde71f8cb0  EFLAGS: 00000202
RAX: 0000000000000001 RBX: 00000000006dac58 RCX: 00000000004496b9
RDX: 0000000000000012 RSI: 00000000004ae17d RDI: 0000000000000011
RBP: 0000000000000001 R08: 00000000004002e0 R09: 00000000004002e0
R10: 00000000004002e0 R11: 0000000000000206 R12: 00000000006dac44
R13: 00000000006dadc0 R14: 000000000000000c R15: 0000000000000011
FS:  0000000001b8b880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000056213d70e000 CR3: 00000001d87a0000 CR4: 00000000001606f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400