INFO: task syz-executor2:20828 blocked for more than 120 seconds.
      Not tainted 4.9.40-ged32335 #10
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor2   D29040 20828   3414 0x00000004
 ffff8801cd0e9780 ffff8801d8df24c0 ffff8801d5b7da40 ffff8801d8de2f00
 ffff8801db321498 ffff8801a5d479a0 ffffffff838a22bb 0000000041b58ab3
 ffffffff841902c8 00ffffff812373d0 ffff8801db321db0 ffff8801db321dd8
Call Trace:
 [<ffffffff838a3872>] schedule+0x92/0x1b0 kernel/sched/core.c:3624
 [<ffffffff838afb12>] schedule_timeout+0x6a2/0xec0 kernel/time/timer.c:1738
 [<ffffffff838a1a6e>] io_schedule_timeout+0x1be/0x390 kernel/sched/core.c:5242
 [<ffffffff838a4ce9>] io_schedule include/linux/sched.h:460 [inline]
 [<ffffffff838a4ce9>] bit_wait_io+0x19/0xa0 kernel/sched/wait.c:582
 [<ffffffff838a43c7>] __wait_on_bit+0x57/0x120 kernel/sched/wait.c:383
 [<ffffffff8142c704>] wait_on_page_bit+0xf4/0x140 mm/filemap.c:802
 [<ffffffff8142c911>] wait_on_page_writeback include/linux/pagemap.h:526 [inline]
 [<ffffffff8142c911>] __filemap_fdatawait_range+0x1c1/0x2b0 mm/filemap.c:453
 [<ffffffff81436883>] filemap_fdatawait_keep_errors+0x63/0x80 mm/filemap.c:511
 [<ffffffff8160ed70>] fdatawait_one_bdev+0x50/0x70 fs/sync.c:94
 [<ffffffff8162a4a9>] iterate_bdevs+0x109/0x260 fs/block_dev.c:1976
 [<ffffffff8160f641>] sys_sync+0xe1/0x170 fs/sync.c:116
 [<ffffffff838b36c5>] entry_SYSCALL_64_fastpath+0x23/0xc6

Showing all locks held in the system:
2 locks held by khungtaskd/519:
 #0:  (rcu_read_lock){......}, at: [<ffffffff8136d275>] check_hung_uninterruptible_tasks kernel/hung_task.c:168 [inline]
 #0:  (rcu_read_lock){......}, at: [<ffffffff8136d275>] watchdog+0x125/0xa70 kernel/hung_task.c:239
 #1:  (tasklist_lock){.+.+..}, at: [<ffffffff81233524>] debug_show_all_locks+0x74/0x290 kernel/locking/lockdep.c:4329
3 locks held by kworker/u4:3/1356:
 #0:  ("writeback"){++++.+}, at: [<ffffffff81189e29>] __write_once_size include/linux/compiler.h:272 [inline]
 #0:  ("writeback"){++++.+}, at: [<ffffffff81189e29>] atomic64_set arch/x86/include/asm/atomic64_64.h:33 [inline]
 #0:  ("writeback"){++++.+}, at: [<ffffffff81189e29>] atomic_long_set include/asm-generic/atomic-long.h:56 [inline]
 #0:  ("writeback"){++++.+}, at: [<ffffffff81189e29>] set_work_data kernel/workqueue.c:615 [inline]
 #0:  ("writeback"){++++.+}, at: [<ffffffff81189e29>] set_work_pool_and_clear_pending kernel/workqueue.c:642 [inline]
 #0:  ("writeback"){++++.+}, at: [<ffffffff81189e29>] process_one_work+0x6a9/0x15f0 kernel/workqueue.c:2089
 #1:  ((&(&wb->dwork)->work)){+.+.+.}, at: [<ffffffff81189e5b>] process_one_work+0x6db/0x15f0 kernel/workqueue.c:2093
 #2:  (&type->s_umount_key#28){.+.+..}, at: [<ffffffff81573320>] trylock_super+0x20/0x100 fs/super.c:393
1 lock held by rsyslogd/3198:
 #0:  (&f->f_pos_lock){+.+.+.}, at: [<ffffffff815cc97f>] __fdget_pos+0x9f/0xc0 fs/file.c:781
2 locks held by getty/3298:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff838b18c2>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+.+.}, at: [<ffffffff81fff0f4>] n_tty_read+0x1f4/0x16c0 drivers/tty/n_tty.c:2133
1 lock held by syz-executor2/20828:
 #0:  (&bdev->bd_mutex){+.+.+.}, at: [<ffffffff8162a468>] iterate_bdevs+0xc8/0x260 fs/block_dev.c:1974
1 lock held by syz-executor2/20839:
 #0:  (&bdev->bd_mutex){+.+.+.}, at: [<ffffffff8162a468>] iterate_bdevs+0xc8/0x260 fs/block_dev.c:1974

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

NMI backtrace for cpu 0
CPU: 0 PID: 519 Comm: khungtaskd Not tainted 4.9.40-ged32335 #10
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801d88a7d00 ffffffff81d8d829 0000000000000000 0000000000000000
 0000000000000000 0000000000000001 ffffffff810bd010 ffff8801d88a7d38
 ffffffff81d9893d 0000000000000000 0000000000000000 ffff8801d68a6198
Call Trace:
 [<ffffffff81d8d829>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81d8d829>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff81d9893d>] nmi_cpu_backtrace+0xfd/0x120 lib/nmi_backtrace.c:99
 [<ffffffff81d98a77>] nmi_trigger_cpumask_backtrace+0x117/0x190 lib/nmi_backtrace.c:60
 [<ffffffff810bd104>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37
 [<ffffffff8136d840>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline]
 [<ffffffff8136d840>] check_hung_task kernel/hung_task.c:125 [inline]
 [<ffffffff8136d840>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline]
 [<ffffffff8136d840>] watchdog+0x6f0/0xa70 kernel/hung_task.c:239
 [<ffffffff8119ad8d>] kthread+0x26d/0x300 kernel/kthread.c:211
 [<ffffffff838b396a>] ret_from_fork+0x2a/0x40 arch/x86/entry/entry_64.S:433
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.9.40-ged32335 #10
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8801da29af00 task.stack: ffff8801da2b0000
RIP: 0010:[<ffffffff81205b43>] 
c [<ffffffff81205b43>] find_busiest_group+0x333/0xef0 kernel/sched/fair.c:8423
RSP: 0018:ffff8801db307a80  EFLAGS: 00000a03
RAX: dffffc0000000000 RBX: ffff8801db307cc0 RCX: 00000000000007e3
RDX: 0000000000000003 RSI: 0000000000000000 RDI: ffff8801db307cec
RBP: ffff8801db307be8 R08: 1ffff1003b660f9d R09: 000000000000000c
R10: ffff8801db221480 R11: 000000000000000c R12: ffff8801db307bc0
R13: 1ffff1003b660f58 R14: ffff8801da15ed80 R15: 0000000000000fc6
FS:  0000000000000000(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000c434272618 CR3: 00000001d0644000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 0000000000000046
c 0000000000000046
c ffff8801da29af00
c ffff8801db321498
c
 ffffffff83a575a0
c 000000000000024d
c ffff8801db307ce8
c 0000000041b58ab3
c
 0000000041b58ab3
c ffffffff84189ac3
c ffffffff81205810
c ffffffff81dd8a50
c
Call Trace:
 [<ffffffff81206a3c>] load_balance+0x33c/0x2d50 kernel/sched/fair.c:8669
 [<ffffffff8120bac8>] rebalance_domains+0x5f8/0xb00 kernel/sched/fair.c:9319
 [<ffffffff8120c2e1>] run_rebalance_domains+0x311/0x610 kernel/sched/fair.c:9533
 [<ffffffff838b655d>] __do_softirq+0x22d/0x964 kernel/softirq.c:284
 [<ffffffff811478c5>] invoke_softirq kernel/softirq.c:364 [inline]
 [<ffffffff811478c5>] irq_exit+0x165/0x190 kernel/softirq.c:405
 [<ffffffff810aeccb>] smp_reschedule_interrupt+0x6b/0x80 arch/x86/kernel/smp.c:267
 [<ffffffff838b575c>] reschedule_interrupt+0x8c/0xa0 arch/x86/entry/entry_64.S:732
 <EOI> 
d [<ffffffff838b2336>] ? native_safe_halt+0x6/0x10 arch/x86/include/asm/irqflags.h:53
 [<ffffffff838b1965>] arch_safe_halt arch/x86/include/asm/paravirt.h:103 [inline]
 [<ffffffff838b1965>] default_idle+0x55/0x360 arch/x86/kernel/process.c:295
 [<ffffffff8106c35a>] arch_cpu_idle+0xa/0x10 arch/x86/kernel/process.c:286
 [<ffffffff838b2786>] default_idle_call+0x36/0x60 kernel/sched/idle.c:97
 [<ffffffff812263bc>] cpuidle_idle_call kernel/sched/idle.c:155 [inline]
 [<ffffffff812263bc>] cpu_idle_loop kernel/sched/idle.c:248 [inline]
 [<ffffffff812263bc>] cpu_startup_entry+0x30c/0x3d0 kernel/sched/idle.c:303
 [<ffffffff810b1583>] start_secondary+0x303/0x3e0 arch/x86/kernel/smpboot.c:262
Code: 
c24 
c84 
c48 
c89 
cc1 
c49 
c89 
c84 
c24 
c40 
cff 
cff 
cff 
c83 
cfa 
c02 
c0f 
c84 
c64 
c05 
c00 
c00 
c48 
c8d 
c7b 
c2c 
c48 
cb8 
c00 
c00 
c00 
c00 
c00 
cfc 
cff 
cdf 
c49 
c89 
cf8 
c49 
cc1 
ce8 
c03 
c<45> 
c0f 
cb6 
c04 
c00 
c48 
c89 
cf8 
c83 
ce0 
c07 
c83 
cc0 
c03 
c44 
c38 
cc0 
c7c 
c09 
c45 
c84 
c