INFO: task syz-executor0:22618 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-executor0   D29000 22618   3372 0x00000104
 ffff8801cb31af00 ffff8801d14caa00 ffff8801d03a9500 ffff8801c997af00
 ffff8801db321498 ffff8801cc0c7940 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
 [<ffffffff81006527>] do_syscall_64+0x197/0x490 arch/x86/entry/common.c:280
 [<ffffffff838b378d>] entry_SYSCALL64_slow_path+0x25/0x25

Showing all locks held in the system:
3 locks held by kworker/u4:0/6:
 #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
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
1 lock held by rsyslogd/3187:
 #0:  (&f->f_pos_lock){+.+.+.}, at: [<ffffffff815cc97f>] __fdget_pos+0x9f/0xc0 fs/file.c:781
2 locks held by getty/3280:
 #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-executor0/22618:
 #0:  (&bdev->bd_mutex){+.+.+.}, at: [<ffffffff8162a468>] iterate_bdevs+0xc8/0x260 fs/block_dev.c:1974
1 lock held by syz-executor0/22634:
 #0:  (&bdev->bd_mutex){+.+.+.}, at: [<ffffffff8162a468>] iterate_bdevs+0xc8/0x260 fs/block_dev.c:1974
1 lock held by syz-executor3/22638:
 #0:  (&bdev->bd_mutex){+.+.+.}, at: [<ffffffff816273dc>] __blkdev_get+0x10c/0xd50 fs/block_dev.c:1266
1 lock held by syz-executor3/22641:
 #0:  (&bdev->bd_mutex){+.+.+.}, at: [<ffffffff816273dc>] __blkdev_get+0x10c/0xd50 fs/block_dev.c:1266
1 lock held by syz-executor5/22693:
 #0:  (&bdev->bd_mutex){+.+.+.}, at: [<ffffffff816273dc>] __blkdev_get+0x10c/0xd50 fs/block_dev.c:1266
1 lock held by syz-executor5/22698:
 #0:  (&bdev->bd_mutex){+.+.+.}, at: [<ffffffff816273dc>] __blkdev_get+0x10c/0xd50 fs/block_dev.c:1266

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

NMI backtrace for cpu 1
CPU: 1 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
 ffff8801d8987d00 ffffffff81d8d829 0000000000000000 0000000000000001
 0000000000000001 0000000000000001 ffffffff810bd010 ffff8801d8987d38
 ffffffff81d9893d 0000000000000001 0000000000000000 ffff8801cb319b18
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 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.9.40-ged32335 #10
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffffffff84426880 task.stack: ffffffff84400000
RIP: 0010:[<ffffffff810c6aec>] 
c [<ffffffff810c6aec>] native_apic_mem_write+0xc/0x10 arch/x86/include/asm/apic.h:98
RSP: 0018:ffff8801db207fd0  EFLAGS: 00010046
RAX: dffffc0000000000 RBX: ffffffff841fe840 RCX: 0000000000000000
RDX: 1ffffffff083fd26 RSI: 0000000000000000 RDI: 00000000000000b0
RBP: ffff8801db207fd0 R08: 0000000000000001 R09: ffff88021fffd008
R10: ffff88021fffd018 R11: ffff88021fffd010 R12: 0000000000000000
R13: 0000000000000000 R14: ffffffff84a2e378 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000c436917810 CR3: 00000001cdda1000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 ffff8801db207fe8
c ffffffff810aecba
c ffffffff84a1f508
c ffffffff84407db8
c
 ffffffff838b575c
c ffffffff84407d08
c <EOI> 
c 0000000000000000
c ffffffff84a2e378
c
 0000000000000000
c 0000000000000000
c ffffffff84407db8
c ffffffff84a1f508
c
Call Trace:
 <IRQ> 
d [<ffffffff810aecba>] apic_eoi arch/x86/include/asm/apic.h:403 [inline]
 <IRQ> 
d [<ffffffff810aecba>] ack_APIC_irq arch/x86/include/asm/apic.h:447 [inline]
 <IRQ> 
d [<ffffffff810aecba>] smp_reschedule_interrupt+0x5a/0x80 arch/x86/kernel/smp.c:265
 [<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
 [<ffffffff8389ee94>] rest_init+0x184/0x190 init/main.c:408
 [<ffffffff84a668a7>] start_kernel+0x679/0x6ae init/main.c:662
 [<ffffffff84a6529d>] x86_64_start_reservations+0x2a/0x2c arch/x86/kernel/head64.c:196
 [<ffffffff84a653df>] x86_64_start_kernel+0x140/0x163 arch/x86/kernel/head64.c:177
Code: 
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c