INFO: task syz-executor5:9059 blocked for more than 120 seconds.
      Not tainted 4.9.67-g12cae95 #105
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor5   D28784  9059   3592 0x00000004
 ffff8801a4523000 ffff8801a292e4c0 ffff8801a292e4c0 ffff8801a8ea9800
 ffff8801db221418 ffff8801c7247ba8 ffffffff838981cb 0000000000000001
 0000000000000007 00ff8801a4523000 ffff8801db221ce8 ffff8801db221d10
Call Trace:
 [<ffffffff8389976f>] schedule+0x7f/0x1b0 kernel/sched/core.c:3550
 [<ffffffff8389a0f3>] schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3583
 [<ffffffff8389f702>] __mutex_lock_common kernel/locking/mutex.c:582 [inline]
 [<ffffffff8389f702>] mutex_lock_nested+0x312/0x870 kernel/locking/mutex.c:621
 [<ffffffff824b0f46>] loop_control_ioctl+0x176/0x300 drivers/block/loop.c:1907
 [<ffffffff815aa59a>] vfs_ioctl fs/ioctl.c:43 [inline]
 [<ffffffff815aa59a>] do_vfs_ioctl+0x1aa/0x1140 fs/ioctl.c:679
 [<ffffffff815ab5bf>] SYSC_ioctl fs/ioctl.c:694 [inline]
 [<ffffffff815ab5bf>] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:685
 [<ffffffff838a9985>] entry_SYSCALL_64_fastpath+0x23/0xc6

Showing all locks held in the system:
2 locks held by khungtaskd/514:
 #0:  (rcu_read_lock){......}, at: [<ffffffff8136fe05>] check_hung_uninterruptible_tasks kernel/hung_task.c:168 [inline]
 #0:  (rcu_read_lock){......}, at: [<ffffffff8136fe05>] watchdog+0x125/0xa70 kernel/hung_task.c:239
 #1:  (tasklist_lock){.+.+..}, at: [<ffffffff812355d0>] debug_show_all_locks+0x70/0x280 kernel/locking/lockdep.c:4336
1 lock held by rsyslogd/3140:
 #0:  (&f->f_pos_lock){+.+.+.}, at: [<ffffffff815cf8df>] __fdget_pos+0x9f/0xc0 fs/file.c:781
2 locks held by getty/3228:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff838a7b92>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+.+.}, at: [<ffffffff82001d24>] n_tty_read+0x1f4/0x16c0 drivers/tty/n_tty.c:2133
2 locks held by syz-executor5/9059:
 #0:  (loop_index_mutex){+.+.+.}, at: [<ffffffff824b0e4a>] loop_control_ioctl+0x7a/0x300 drivers/block/loop.c:1893
 #1:  (&lo->lo_ctl_mutex#2){+.+.+.}, at: [<ffffffff824b0f46>] loop_control_ioctl+0x176/0x300 drivers/block/loop.c:1907
1 lock held by syz-executor5/9112:
 #0:  (loop_index_mutex){+.+.+.}, at: [<ffffffff824b0e4a>] loop_control_ioctl+0x7a/0x300 drivers/block/loop.c:1893
2 locks held by syz-executor4/9078:
 #0:  (&lo->lo_ctl_mutex/1){+.+.+.}, at: [<ffffffff824ae98f>] lo_ioctl+0x8f/0x1990 drivers/block/loop.c:1337
 #1:  (&bdev->bd_mutex){+.+.+.}, at: [<ffffffff81d325de>] blkdev_reread_part+0x1e/0x40 block/ioctl.c:189
1 lock held by syz-executor4/9089:
 #0:  (&lo->lo_ctl_mutex/1){+.+.+.}, at: [<ffffffff824ae98f>] lo_ioctl+0x8f/0x1990 drivers/block/loop.c:1337
2 locks held by blkid/9108:
 #0:  (&bdev->bd_mutex){+.+.+.}, at: [<ffffffff8162a1fc>] __blkdev_get+0x10c/0xd50 fs/block_dev.c:1268
 #1:  (loop_index_mutex){+.+.+.}, at: [<ffffffff824a98eb>] lo_open+0x1b/0xa0 drivers/block/loop.c:1548

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

NMI backtrace for cpu 1
CPU: 1 PID: 514 Comm: khungtaskd Not tainted 4.9.67-g12cae95 #105
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801d893fd00 ffffffff81d906e9 0000000000000000 0000000000000001
 0000000000000001 0000000000000001 ffffffff810ba170 ffff8801d893fd38
 ffffffff81d9b80d 0000000000000001 0000000000000000 ffff8801a8d6cc18
Call Trace:
 [<ffffffff81d906e9>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81d906e9>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff81d9b80d>] nmi_cpu_backtrace+0xfd/0x120 lib/nmi_backtrace.c:99
 [<ffffffff81d9b947>] nmi_trigger_cpumask_backtrace+0x117/0x190 lib/nmi_backtrace.c:60
 [<ffffffff810ba264>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37
 [<ffffffff813703d0>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline]
 [<ffffffff813703d0>] check_hung_task kernel/hung_task.c:125 [inline]
 [<ffffffff813703d0>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline]
 [<ffffffff813703d0>] watchdog+0x6f0/0xa70 kernel/hung_task.c:239
 [<ffffffff811985ad>] kthread+0x26d/0x300 kernel/kthread.c:211
 [<ffffffff838a9c2a>] ret_from_fork+0x2a/0x40 arch/x86/entry/entry_64.S:433
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.9.67-g12cae95 #105
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffffffff84426880 task.stack: ffffffff84400000
RIP: 0010:[<ffffffff838ab990>] 
c [<ffffffff838ab990>] reschedule_interrupt+0x0/0xa0 arch/x86/entry/entry_64.S:731
RSP: 0018:ffffffff84407d98  EFLAGS: 00000046
RAX: 0000000000000007 RBX: ffffffff84a1f5e8 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000001 RDI: ffffffff8442712c
RBP: ffffffff84407dc0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: ffffffff84a2e6f8 R14: 0000000000000000 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000000215b000 CR3: 00000001d038c000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 ffffffff838a8606
c 0000000000000010
c 0000000000000246
c ffffffff84407dc0
c
 0000000000000018
c ffffffff84407df8
c ffffffff838a7c35
c ffffffff84426880
c
 0000000000000000
c ffffffff84a2e6f8
c 0000000000000000
c 0000000000000000
c
Call Trace:
 [<ffffffff838a7c35>] arch_safe_halt arch/x86/include/asm/paravirt.h:103 [inline]
 [<ffffffff838a7c35>] default_idle+0x55/0x360 arch/x86/kernel/process.c:295
 [<ffffffff8106baca>] arch_cpu_idle+0xa/0x10 arch/x86/kernel/process.c:286
 [<ffffffff838a8a46>] default_idle_call+0x36/0x60 kernel/sched/idle.c:97
 [<ffffffff81223bd0>] cpuidle_idle_call kernel/sched/idle.c:155 [inline]
 [<ffffffff81223bd0>] cpu_idle_loop kernel/sched/idle.c:248 [inline]
 [<ffffffff81223bd0>] cpu_startup_entry+0x2b0/0x380 kernel/sched/idle.c:303
 [<ffffffff83894e14>] rest_init+0x184/0x190 init/main.c:407
 [<ffffffff84a668a7>] start_kernel+0x679/0x6ae init/main.c:661
 [<ffffffff84a6529d>] x86_64_start_reservations+0x2a/0x2c arch/x86/kernel/head64.c:196
 [<ffffffff84a653df>] x86_64_start_kernel+0x140/0x163 arch/x86/kernel/head64.c:177
Code: 
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c