INFO: task syz-executor1:22687 blocked for more than 120 seconds.
      Not tainted 4.9.76-g8dec074 #13
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor1   D28976 22687   9312 0x00000004
 ffff8801d9b71800 ffff8801c337ca80 ffff8801cbacef40 ffff8801ade0c800
 ffff8801db321b98 ffff8801c2acfb00 ffffffff8389f9fb 0000000041b58ab3
 ffffffff84191ca8 00ffffff8123ad50 ffff8801db322468 ffff8801db322490
Call Trace:
 [<ffffffff838a0f9f>] schedule+0x7f/0x1b0 kernel/sched/core.c:3550
 [<ffffffff838ad0fc>] schedule_timeout+0x56c/0x10b0 kernel/time/timer.c:1768
 [<ffffffff8389f1ae>] io_schedule_timeout+0x1be/0x390 kernel/sched/core.c:5172
 [<ffffffff838a290e>] do_wait_for_common kernel/sched/completion.c:75 [inline]
 [<ffffffff838a290e>] __wait_for_common kernel/sched/completion.c:93 [inline]
 [<ffffffff838a290e>] wait_for_common_io kernel/sched/completion.c:107 [inline]
 [<ffffffff838a290e>] wait_for_completion_io+0x20e/0x2e0 kernel/sched/completion.c:155
 [<ffffffff81cd9a5b>] submit_bio_wait+0x11b/0x180 block/bio.c:885
 [<ffffffff81d0cc07>] blkdev_issue_flush+0x157/0x220 block/blk-flush.c:518
 [<ffffffff81628e85>] blkdev_fsync+0x85/0xb0 fs/block_dev.c:378
 [<ffffffff816147ea>] vfs_fsync_range+0x10a/0x250 fs/sync.c:195
 [<ffffffff816149a2>] vfs_fsync fs/sync.c:209 [inline]
 [<ffffffff816149a2>] do_fsync+0x42/0xb0 fs/sync.c:219
 [<ffffffff81615149>] SYSC_fdatasync fs/sync.c:233 [inline]
 [<ffffffff81615149>] SyS_fdatasync+0x19/0x20 fs/sync.c:231
 [<ffffffff838b0aa8>] entry_SYSCALL_64_fastpath+0x23/0xe2

Showing all locks held in the system:
2 locks held by khungtaskd/515:
 #0:  (rcu_read_lock){......}, at: [<ffffffff81371d35>] check_hung_uninterruptible_tasks kernel/hung_task.c:168 [inline]
 #0:  (rcu_read_lock){......}, at: [<ffffffff81371d35>] watchdog+0x125/0xa70 kernel/hung_task.c:239
 #1:  (tasklist_lock){.+.+..}, at: [<ffffffff81236eb0>] debug_show_all_locks+0x70/0x280 kernel/locking/lockdep.c:4336
2 locks held by getty/3308:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff838aec72>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+.+.}, at: [<ffffffff820084b4>] n_tty_read+0x1f4/0x16c0 drivers/tty/n_tty.c:2133

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

NMI backtrace for cpu 0
CPU: 0 PID: 515 Comm: khungtaskd Not tainted 4.9.76-g8dec074 #13
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801d892fd00 ffffffff81d93169 0000000000000000 0000000000000000
 0000000000000000 0000000000000001 ffffffff810ba750 ffff8801d892fd38
 ffffffff81d9e28d 0000000000000000 0000000000000000 ffff8801c2a00418
Call Trace:
 [<ffffffff81d93169>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81d93169>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff81d9e28d>] nmi_cpu_backtrace+0xfd/0x120 lib/nmi_backtrace.c:99
 [<ffffffff81d9e3c7>] nmi_trigger_cpumask_backtrace+0x117/0x190 lib/nmi_backtrace.c:60
 [<ffffffff810ba844>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37
 [<ffffffff81372300>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline]
 [<ffffffff81372300>] check_hung_task kernel/hung_task.c:125 [inline]
 [<ffffffff81372300>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline]
 [<ffffffff81372300>] watchdog+0x6f0/0xa70 kernel/hung_task.c:239
 [<ffffffff811996ad>] kthread+0x26d/0x300 kernel/kthread.c:211
 [<ffffffff838b0db6>] ret_from_fork+0x46/0x60 arch/x86/entry/entry_64.S:460
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.9.76-g8dec074 #13
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8801da3d3000 task.stack: ffff8801da3e8000
RIP: 0010:[<ffffffff8114385c>] 
c [<ffffffff8114385c>] arch_local_irq_restore arch/x86/include/asm/paravirt.h:767 [inline]
RIP: 0010:[<ffffffff8114385c>] 
c [<ffffffff8114385c>] __local_bh_disable_ip+0x4c/0x110 kernel/softirq.c:126
RSP: 0018:ffff8801db307fa0  EFLAGS: 00000046
RAX: 0000000080000201 RBX: 0000000000000200 RCX: 0000000000000001
RDX: 0000000000000000 RSI: 0000000000000200 RDI: 0000000000000046
RBP: ffff8801db307fb8 R08: 0000000000000000 R09: 0000000000000001
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000046
R13: ffffffff811459dd R14: 0000000000000000 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f89cb66b9b8 CR3: 00000001ce434000 CR4: 0000000000160670
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 ffff8801da3d3000
c 0000000000000001
c ffffffff84a36578
c ffff8801db307fd0
c
 ffffffff811459ee
c ffffffff84a27468
c ffff8801db307fe8
c ffffffff838b528a
c
 ffffffff84a27468
c ffff8801da3efd98
c ffffffff838b2f00
c ffff8801da3efce8
c
Call Trace:
 <IRQ> 
d [<ffffffff811459ee>] local_bh_disable include/linux/bottom_half.h:18 [inline]
 <IRQ> 
d [<ffffffff811459ee>] irq_enter+0xae/0xd0 kernel/softirq.c:344
 [<ffffffff838b528a>] smp_reschedule_interrupt+0xa/0x80 arch/x86/kernel/smp.c:264
 [<ffffffff838b2f00>] reschedule_interrupt+0xa0/0xb0 arch/x86/entry/entry_64.S:758
 <EOI> 
d [<ffffffff838af6e6>] ? native_safe_halt+0x6/0x10 arch/x86/include/asm/irqflags.h:53
 [<ffffffff838aed15>] arch_safe_halt arch/x86/include/asm/paravirt.h:103 [inline]
 [<ffffffff838aed15>] default_idle+0x55/0x360 arch/x86/kernel/process.c:295
 [<ffffffff8106bbca>] arch_cpu_idle+0xa/0x10 arch/x86/kernel/process.c:286
 [<ffffffff838afb26>] default_idle_call+0x36/0x60 kernel/sched/idle.c:97
 [<ffffffff812254b0>] cpuidle_idle_call kernel/sched/idle.c:155 [inline]
 [<ffffffff812254b0>] cpu_idle_loop kernel/sched/idle.c:248 [inline]
 [<ffffffff812254b0>] cpu_startup_entry+0x2b0/0x380 kernel/sched/idle.c:303
 [<ffffffff810af803>] start_secondary+0x303/0x3e0 arch/x86/kernel/smpboot.c:254
Code: 
c58 
c0f 
c1f 
c44 
c00 
c00 
c49 
c89 
cc4 
cfa 
c66 
c0f 
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c44 
c00 
c00 
c65 
c01 
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c88 
c44 
ced 
c7e 
c65 
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c44 
ced 
c7e 
c48 
c31 
cd8 
cf6 
cc4 
cff 
c74 
c21 
c4c 
c89 
ce7 
c57 
c9d 
c<0f> 
c1f 
c44 
c00 
c00 
c65 
c8b 
c05 
c68 
c44 
ced 
c7e 
c25 
cff 
cff 
cff 
c7f 
c39 
cd8 
c74 
c11 
c