INFO: task jbd2/sda1-8:1923 blocked for more than 140 seconds.
      Not tainted 4.9.112-g9e79039 #7
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
jbd2/sda1-8     D26872  1923      2 0x00000000
 ffff8801cd976000 0000000000000000 ffff8801b710ef40 ffff8801d30f8000
 ffff8801db321c18 ffff8801cdbef580 ffffffff839e907d 0000000041b58ab3
 ffffffff843c36c0 ffffffff812361d0 0000000200000012 ffff8801db3224e8
Call Trace:
 [<ffffffff839ea67f>] schedule+0x7f/0x1b0 kernel/sched/core.c:3557
 [<ffffffff839f6a91>] schedule_timeout+0x861/0xf70 kernel/time/timer.c:1768
 [<ffffffff839e885a>] io_schedule_timeout+0x1ba/0x390 kernel/sched/core.c:5180
 [<ffffffff839ebac9>] io_schedule include/linux/sched.h:460 [inline]
 [<ffffffff839ebac9>] bit_wait_io+0x19/0xa0 kernel/sched/wait.c:582
 [<ffffffff839eb213>] __wait_on_bit+0x93/0x120 kernel/sched/wait.c:383
 [<ffffffff839eb548>] out_of_line_wait_on_bit+0xe8/0x120 kernel/sched/wait.c:396
 [<ffffffff8162321c>] wait_on_bit_io include/linux/wait.h:1070 [inline]
 [<ffffffff8162321c>] __wait_on_buffer+0x5c/0x70 fs/buffer.c:124
 [<ffffffff818926e2>] wait_on_buffer include/linux/buffer_head.h:347 [inline]
 [<ffffffff818926e2>] journal_wait_on_commit_record fs/jbd2/commit.c:176 [inline]
 [<ffffffff818926e2>] jbd2_journal_commit_transaction+0x4342/0x6050 fs/jbd2/commit.c:875
 [<ffffffff818a456a>] kjournald2+0x22a/0x830 fs/jbd2/journal.c:224
 [<ffffffff8119d0bd>] kthread+0x26d/0x300 kernel/kthread.c:211
 [<ffffffff839fa11c>] ret_from_fork+0x5c/0x70 arch/x86/entry/entry_64.S:373

Showing all locks held in the system:
2 locks held by khungtaskd/518:
 #0:  (rcu_read_lock){......}, at: [<ffffffff8136675c>] check_hung_uninterruptible_tasks kernel/hung_task.c:168 [inline]
 #0:  (rcu_read_lock){......}, at: [<ffffffff8136675c>] watchdog+0x11c/0xa20 kernel/hung_task.c:239
 #1:  (tasklist_lock){.+.+..}, at: [<ffffffff81425de7>] debug_show_all_locks+0x79/0x218 kernel/locking/lockdep.c:4336
2 locks held by getty/3779:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff839f8122>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+...}, at: [<ffffffff8211edc2>] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2142
1 lock held by syz-executor3/4727:
 #0:  (uuid_mutex){+.+.+.}, at: [<ffffffff81ab1f36>] btrfs_scan_one_device+0xa6/0x440 fs/btrfs/volumes.c:1140
3 locks held by syz-executor5/4720:
 #0:  (&bdev->bd_mutex){+.+.+.}, at: [<ffffffff81630b5b>] __blkdev_put+0xbb/0x840 fs/block_dev.c:1579
 #1:  (loop_index_mutex){+.+.+.}, at: [<ffffffff825cc7cf>] lo_release+0x1f/0x1a0 drivers/block/loop.c:1597
 #2:  (&lo->lo_ctl_mutex#2){+.+.+.}, at: [<ffffffff825cc835>] __lo_release drivers/block/loop.c:1575 [inline]
 #2:  (&lo->lo_ctl_mutex#2){+.+.+.}, at: [<ffffffff825cc835>] lo_release+0x85/0x1a0 drivers/block/loop.c:1598
1 lock held by syz-executor5/4747:
 #0:  (&bdev->bd_mutex){+.+.+.}, at: [<ffffffff816313ec>] __blkdev_get+0x10c/0xd60 fs/block_dev.c:1268

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

NMI backtrace for cpu 1
CPU: 1 PID: 518 Comm: khungtaskd Not tainted 4.9.112-g9e79039 #7
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801d91b7d08 ffffffff81eb3249 0000000000000000 0000000000000001
 0000000000000001 0000000000000001 ffffffff810b9bd0 ffff8801d91b7d40
 ffffffff81ebe547 0000000000000001 0000000000000000 0000000000000002
Call Trace:
 [<ffffffff81eb3249>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81eb3249>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff81ebe547>] nmi_cpu_backtrace.cold.2+0x48/0x87 lib/nmi_backtrace.c:99
 [<ffffffff81ebe4da>] nmi_trigger_cpumask_backtrace+0x12a/0x14f lib/nmi_backtrace.c:60
 [<ffffffff810b9cd4>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37
 [<ffffffff81366cf4>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline]
 [<ffffffff81366cf4>] check_hung_task kernel/hung_task.c:125 [inline]
 [<ffffffff81366cf4>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline]
 [<ffffffff81366cf4>] watchdog+0x6b4/0xa20 kernel/hung_task.c:239
 [<ffffffff8119d0bd>] kthread+0x26d/0x300 kernel/kthread.c:211
 [<ffffffff839fa11c>] ret_from_fork+0x5c/0x70 arch/x86/entry/entry_64.S:373
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 3881 Comm: syz-executor1 Not tainted 4.9.112-g9e79039 #7
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8801d86eb000 task.stack: ffff8801a07e0000
RIP: 0010:[<ffffffff812365df>] 
c [<ffffffff812365df>] __lock_acquire+0x40f/0x4070 kernel/locking/lockdep.c:3293
RSP: 0018:ffff8801a07e79d0  EFLAGS: 00000002
RAX: 0000000000000004 RBX: ffff8801d86eb940 RCX: 000000000000000e
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff8801d86eb964
RBP: ffff8801a07e7b78 R08: 0000000000000001 R09: 0000000000000000
R10: ffff8801d86eb000 R11: 1ffff1003b0dd727 R12: 0000000000000056
R13: 0000000000000003 R14: ffff8801d86eb8b4 R15: 0000000000000000
FS:  0000000002372940(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffcb4b2cf9c CR3: 00000001a062a000 CR4: 00000000001606f0
DR0: 0000000020000000 DR1: 00000000200001c0 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600
Stack:
 ffff8801d86eb8b4
c ffff8801d86eb962
c ffff8801a07e7b98
c 0000000000000046
c
 ffff8801d86eb000
c dffffc0000000000
c ffff8801a07e7a40
c ffff8801a07e7a48
c
 ffffffff81f1acab
c ffffffff846c9760
c ffffffff846c9760
c 000060fe24a24448
c
Call Trace:
 [<ffffffff8123acb0>] lock_acquire+0x130/0x3e0 kernel/locking/lockdep.c:3756
 [<ffffffff839f9316>] __raw_spin_lock include/linux/spinlock_api_smp.h:144 [inline]
 [<ffffffff839f9316>] _raw_spin_lock+0x36/0x50 kernel/locking/spinlock.c:151
 [<ffffffff815c40df>] spin_lock include/linux/spinlock.h:302 [inline]
 [<ffffffff815c40df>] d_walk+0xef/0x720 fs/dcache.c:1220
 [<ffffffff815c4882>] shrink_dcache_parent+0xd2/0x120 fs/dcache.c:1450
 [<ffffffff81595fd2>] vfs_rmdir2+0x1d2/0x420 fs/namei.c:3884
 [<ffffffff815aa75f>] do_rmdir+0x3af/0x3f0 fs/namei.c:3951
 [<ffffffff815ac8ba>] SYSC_rmdir fs/namei.c:3969 [inline]
 [<ffffffff815ac8ba>] SyS_rmdir+0x1a/0x20 fs/namei.c:3967
 [<ffffffff81006316>] do_syscall_64+0x1a6/0x490 arch/x86/entry/common.c:282
 [<ffffffff839f9f53>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb
Code: 
ce6 
c07 
c01 
cc2 
c0f 
cb6 
c43 
c21 
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c03 
cc1 
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c05 
c83 
ce0 
c1f 
c09 
cd0 
c89 
cca 
c0f 
cb6 
c4b 
c22 
c41 
c89 
cc7 
c44 
c89 
cc0 
c83 
ce2 
c03 
c83 
ce0 
c01 
c41 
c09 
cf7 
cc1 
ce0 
c02 
c<44> 
c88 
c7b 
c21 
c83 
ce1 
cf8 
c09 
cd1 
c09 
cc1 
c45 
c85 
cc9 
c0f 
c95 
cc0 
c83 
ce1 
cf7 
cc1 
c