INFO: task syz-executor4:27733 blocked for more than 120 seconds.
      Not tainted 4.9.107-gdb2c520 #49
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor4   D29000 27733   3820 0x00000004
 ffff8801be8b8000 0000000000000000 ffff8801d3fb7480 ffffffff84629800
 ffff8801db221c18 ffff8801cdc97aa0 ffffffff839e8c1d 1ffff10039b92f48
 ffffffff85542240 0000000041b58ab3 00ffffff843c2388 ffff8801db2224e8
Call Trace:
 [<ffffffff839ea21f>] schedule+0x7f/0x1b0 kernel/sched/core.c:3557
 [<ffffffff839f6631>] schedule_timeout+0x861/0xf70 kernel/time/timer.c:1768
 [<ffffffff839e83fa>] io_schedule_timeout+0x1ba/0x390 kernel/sched/core.c:5180
 [<ffffffff839ebb53>] do_wait_for_common kernel/sched/completion.c:75 [inline]
 [<ffffffff839ebb53>] __wait_for_common kernel/sched/completion.c:93 [inline]
 [<ffffffff839ebb53>] wait_for_common_io kernel/sched/completion.c:107 [inline]
 [<ffffffff839ebb53>] wait_for_completion_io+0x203/0x2e0 kernel/sched/completion.c:155
 [<ffffffff81dfb5a2>] submit_bio_wait+0x112/0x180 block/bio.c:885
 [<ffffffff81e2dcf2>] blkdev_issue_flush+0x152/0x220 block/blk-flush.c:518
 [<ffffffff8162f005>] blkdev_fsync+0x85/0xb0 fs/block_dev.c:378
 [<ffffffff8161a60c>] vfs_fsync_range+0x10c/0x260 fs/sync.c:195
 [<ffffffff8161a7d2>] vfs_fsync fs/sync.c:209 [inline]
 [<ffffffff8161a7d2>] do_fsync+0x42/0xb0 fs/sync.c:219
 [<ffffffff8161af79>] SYSC_fdatasync fs/sync.c:233 [inline]
 [<ffffffff8161af79>] SyS_fdatasync+0x19/0x20 fs/sync.c:231
 [<ffffffff81006316>] do_syscall_64+0x1a6/0x490 arch/x86/entry/common.c:282
 [<ffffffff839f9b13>] 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
1 lock held by rsyslogd/3612:
 #0:  (&f->f_pos_lock){+.+.+.}, at: [<ffffffff815d7fac>] __fdget_pos+0xac/0xd0 fs/file.c:781
2 locks held by getty/3708:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff839f7cc2>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+.+.}, at: [<ffffffff8211fc62>] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2133

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

NMI backtrace for cpu 0
CPU: 0 PID: 519 Comm: khungtaskd Not tainted 4.9.107-gdb2c520 #49
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801d89cfd08 ffffffff81eb3da9 0000000000000000 0000000000000000
 0000000000000000 0000000000000001 ffffffff810b96a0 ffff8801d89cfd40
 ffffffff81ebf0a7 0000000000000000 0000000000000000 0000000000000003
Call Trace:
 [<ffffffff81eb3da9>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81eb3da9>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff81ebf0a7>] nmi_cpu_backtrace.cold.2+0x48/0x87 lib/nmi_backtrace.c:99
 [<ffffffff81ebf03a>] 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
 [<ffffffff839f9cdc>] 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: 3610 Comm: rs:main Q:Reg Not tainted 4.9.107-gdb2c520 #49
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8801c0d18000 task.stack: ffff8801c0cf0000
RIP: 0010:[<ffffffff81230a55>] 
c [<ffffffff81230a55>] lock_is_held+0x105/0x140 kernel/locking/lockdep.c:3799
RSP: 0018:ffff8801c0cf7408  EFLAGS: 00000246
RAX: 0000000000000007 RBX: 0000000000000003 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff846def20 RDI: 0000000000000246
RBP: ffff8801c0cf7418 R08: ffff8801c0d189d8 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801c0d18000
R13: 0000000000000000 R14: ffffffff8183ccf4 R15: 0000000000000246
FS:  00007f360ff15700(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f2eb7973140 CR3: 00000001bd9e8000 CR4: 00000000001606f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 ffffea0006f80b80
c ffffffff8183ccf4
c ffff8801c0cf7430
c ffffffff8127c053
c
 ffff8801be02eee0
c ffff8801c0cf7468
c ffffffff815382e4
c ffff8801cd94ecb8
c
 0000000000000007
c ffff8801be02eee0
c ffff8801cd94d500
c ffff8801be2af368
c
Call Trace:
 [<ffffffff8127c053>] rcu_read_lock_sched_held+0x103/0x120 kernel/rcu/update.c:112
 [<ffffffff815382e4>] trace_kmem_cache_free include/trace/events/kmem.h:143 [inline]
 [<ffffffff815382e4>] kmem_cache_free+0x294/0x310 mm/slub.c:2981
 [<ffffffff8183ccf4>] ext4_es_free_extent+0x214/0x470 fs/ext4/extents_status.c:370
 [<ffffffff8183f6d1>] __es_remove_extent+0x511/0x830 fs/ext4/extents_status.c:915
 [<ffffffff81841a95>] ext4_es_remove_extent+0xa5/0x310 fs/ext4/extents_status.c:966
 [<ffffffff817ff56c>] ext4_ext_truncate+0x15c/0x280 fs/ext4/extents.c:4647
 [<ffffffff817547b5>] ext4_truncate+0xa15/0x12c0 fs/ext4/inode.c:4259
 [<ffffffff8175694b>] ext4_truncate_failed_write fs/ext4/truncate.h:15 [inline]
 [<ffffffff8175694b>] ext4_da_write_begin+0x4eb/0x1020 fs/ext4/inode.c:3015
 [<ffffffff81435c91>] generic_perform_write+0x301/0x510 mm/filemap.c:2740
 [<ffffffff8143d722>] __generic_file_write_iter+0x352/0x540 mm/filemap.c:2865
 [<ffffffff8172cea3>] ext4_file_write_iter+0x463/0xd90 fs/ext4/file.c:165
 [<ffffffff8156ead0>] new_sync_write fs/read_write.c:496 [inline]
 [<ffffffff8156ead0>] __vfs_write+0x3e0/0x580 fs/read_write.c:509
 [<ffffffff815728c7>] vfs_write+0x187/0x530 fs/read_write.c:557
 [<ffffffff815766f9>] SYSC_write fs/read_write.c:604 [inline]
 [<ffffffff815766f9>] SyS_write+0xd9/0x1c0 fs/read_write.c:596
 [<ffffffff81006316>] do_syscall_64+0x1a6/0x490 arch/x86/entry/common.c:282
 [<ffffffff839f9b13>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb
Code: 
cb6 
c14 
c02 
c48 
c89 
cf8 
c83 
ce0 
c07 
c83 
cc0 
c03 
c38 
cd0 
c7c 
c04 
c84 
cd2 
c75 
c3a 
c41 
cc7 
c84 
c24 
cc4 
c08 
c00 
c00 
c00 
c00 
c00 
c00 
c48 
c89 
cdf 
c57 
c9d 
c0f 
c1f 
c44 
c00 
c00 
c5b 
c<44> 
c89 
ce8 
c41 
c5c 
c41 
c5d 
c5d 
cc3 
c41 
cbd 
c01 
c00 
c00 
c00 
c5b 
c44 
c89 
ce8 
c41 
c5c 
c