INFO: task syz-executor0:15189 blocked for more than 120 seconds.
      Not tainted 4.9.76-g8e170a5 #11
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor0   D29584 15189   5090 0x00000004
 ffff8801cb2c9800 0000000000000000 ffff8801d608e4c0 ffff8801cd8b4800
 ffff8801db221b98 ffff8801cbbdfb00 ffffffff8389f9fb 0000000041b58ab3
 ffffffff84191c90 00ffffff8123ad50 ffff8801db222468 ffff8801db222490
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
 [<ffffffff81cd9a3b>] submit_bio_wait+0x11b/0x180 block/bio.c:885
 [<ffffffff81d0cbe7>] 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/514:
 #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/3301:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff838aec72>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+.+.}, at: [<ffffffff82008494>] n_tty_read+0x1f4/0x16c0 drivers/tty/n_tty.c:2133

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

NMI backtrace for cpu 1
CPU: 1 PID: 514 Comm: khungtaskd Not tainted 4.9.76-g8e170a5 #11
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801d8affd00 ffffffff81d93149 0000000000000000 0000000000000001
 0000000000000001 0000000000000001 ffffffff810ba750 ffff8801d8affd38
 ffffffff81d9e26d 0000000000000001 0000000000000000 ffff8801c9c1cc18
Call Trace:
 [<ffffffff81d93149>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81d93149>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff81d9e26d>] nmi_cpu_backtrace+0xfd/0x120 lib/nmi_backtrace.c:99
 [<ffffffff81d9e3a7>] 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 1 to CPUs 0:
NMI backtrace for cpu 0 skipped: idling at pc 0xffffffff838af6e6