INFO: task syz-executor4:9382 blocked for more than 120 seconds.
      Not tainted 4.9.110-g00a0bcb #7
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor4   D29416  9382   3849 0x20020004
 ffff8801cd756000 0000000000000000 ffff8801d7906f40 ffff8801d9a6b000
 ffff8801db321c18 ffff8801ba797a70 ffffffff839e6ded 0000000041b58ab3
 ffffffff843c30c8 ffffffff81236160 00ff8801d552df80 ffff8801db3224e8
Call Trace:
 [<ffffffff839e83ef>] schedule+0x7f/0x1b0 kernel/sched/core.c:3557
 [<ffffffff839f4801>] schedule_timeout+0x861/0xf70 kernel/time/timer.c:1768
 [<ffffffff839e65ca>] io_schedule_timeout+0x1ba/0x390 kernel/sched/core.c:5180
 [<ffffffff839e9d23>] do_wait_for_common kernel/sched/completion.c:75 [inline]
 [<ffffffff839e9d23>] __wait_for_common kernel/sched/completion.c:93 [inline]
 [<ffffffff839e9d23>] wait_for_common_io kernel/sched/completion.c:107 [inline]
 [<ffffffff839e9d23>] wait_for_completion_io+0x203/0x2e0 kernel/sched/completion.c:155
 [<ffffffff81df9b22>] submit_bio_wait+0x112/0x180 block/bio.c:885
 [<ffffffff81e2c272>] blkdev_issue_flush+0x152/0x220 block/blk-flush.c:518
 [<ffffffff8162f095>] blkdev_fsync+0x85/0xb0 fs/block_dev.c:378
 [<ffffffff8161a69c>] vfs_fsync_range+0x10c/0x260 fs/sync.c:195
 [<ffffffff814ed677>] SYSC_msync mm/msync.c:89 [inline]
 [<ffffffff814ed677>] SyS_msync+0x297/0x3a0 mm/msync.c:31
 [<ffffffff81006da7>] do_syscall_32_irqs_on arch/x86/entry/common.c:325 [inline]
 [<ffffffff81006da7>] do_fast_syscall_32+0x2f7/0x870 arch/x86/entry/common.c:387
 [<ffffffff839f93d0>] entry_SYSENTER_compat+0x90/0xa2 arch/x86/entry/entry_64_compat.S:137

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/3781:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff839f5e92>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+...}, at: [<ffffffff8211e1e2>] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2133

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

NMI backtrace for cpu 0
CPU: 0 PID: 519 Comm: khungtaskd Not tainted 4.9.110-g00a0bcb #7
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801d8457d08 ffffffff81eb2329 0000000000000000 0000000000000000
 0000000000000000 0000000000000001 ffffffff810b9580 ffff8801d8457d40
 ffffffff81ebd627 0000000000000000 0000000000000000 0000000000000002
Call Trace:
 [<ffffffff81eb2329>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81eb2329>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff81ebd627>] nmi_cpu_backtrace.cold.2+0x48/0x87 lib/nmi_backtrace.c:99
 [<ffffffff81ebd5ba>] nmi_trigger_cpumask_backtrace+0x12a/0x14f lib/nmi_backtrace.c:60
 [<ffffffff810b9684>] 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
 [<ffffffff839f7e9c>] 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
CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.9.110-g00a0bcb #7
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8801d9a6b000 task.stack: ffff8801d9a80000
RIP: 0010:[<ffffffff81f19ee5>] 
c [<ffffffff81f19ee5>] __this_cpu_preempt_check+0x5/0x20 lib/smp_processor_id.c:61
RSP: 0018:ffff8801db307fb0  EFLAGS: 00000002
RAX: 0000000000000080 RBX: ffffffff84433860 RCX: 0000000000000000
RDX: 0000000000010001 RSI: 0000000000000000 RDI: ffffffff83c4ad40
RBP: ffff8801db307fb8 R08: 0000000000000001 R09: 0000000000000004
R10: ffffed0043fffa09 R11: 0000000000000001 R12: 0000000000000000
R13: 0000000000000001 R14: ffffffff84c5e688 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f57af6e6140 CR3: 00000001ca4b0000 CR4: 00000000001606f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 ffffffff84433860
c ffff8801db307fd0
c ffffffff8114b1ba
c ffffffff84433860
c
 ffff8801db307fe8
c ffffffff839fc461
c ffffffff84c4e548
c ffff8801d9a87d98
c
 ffffffff839f9fd0
c ffff8801d9a87ce8
c <EOI> 
c 0000000000000000
c ffffffff84c5e688
c
Call Trace:
 <IRQ> 
d [<ffffffff8114b1ba>] ksoftirqd_running kernel/softirq.c:86 [inline]
 <IRQ> 
d [<ffffffff8114b1ba>] invoke_softirq kernel/softirq.c:354 [inline]
 <IRQ> 
d [<ffffffff8114b1ba>] irq_exit+0xda/0x190 kernel/softirq.c:405
 [<ffffffff839fc461>] smp_reschedule_interrupt+0x71/0x90 arch/x86/kernel/smp.c:270
 [<ffffffff839f9fd0>] reschedule_interrupt+0xa0/0xb0 arch/x86/entry/entry_64.S:671
 <EOI> 
d [<ffffffff839f68f6>] ? native_safe_halt+0x6/0x10 arch/x86/include/asm/irqflags.h:53
 [<ffffffff839f5f35>] arch_safe_halt arch/x86/include/asm/paravirt.h:104 [inline]
 [<ffffffff839f5f35>] default_idle+0x55/0x360 arch/x86/kernel/process.c:437
 [<ffffffff8106ad10>] arch_cpu_idle+0x10/0x20 arch/x86/kernel/process.c:428
 [<ffffffff839f6d55>] default_idle_call+0x45/0x60 kernel/sched/idle.c:97
 [<ffffffff81223185>] cpuidle_idle_call kernel/sched/idle.c:155 [inline]
 [<ffffffff81223185>] cpu_idle_loop kernel/sched/idle.c:248 [inline]
 [<ffffffff81223185>] cpu_startup_entry+0x2b5/0x380 kernel/sched/idle.c:303
 [<ffffffff810ae958>] start_secondary+0x328/0x400 arch/x86/kernel/smpboot.c:257
Code: 
c66 
c0f 
c1f 
c44 
c00 
c00 
c55 
c48 
c89 
ce5 
ce8 
c77 
c4a 
c44 
cff 
c48 
cc7 
cc6 
ca0 
cd9 
ce2 
c83 
c48 
cc7 
cc7 
ce0 
cd9 
ce2 
c83 
ce8 
c74 
cfe 
cff 
cff 
c5d 
cc3 
c66 
c90 
c55 
c48 
c89 
ce5 
c53 
c<48> 
c89 
cfb 
ce8 
c53 
c4a 
c44 
cff 
c48 
c89 
cde 
c48 
cc7 
cc7 
c20 
cda 
ce2 
c83 
ce8 
c54 
cfe 
c