Buffer I/O error on dev loop0, logical block 5, lost async page write
Buffer I/O error on dev loop0, logical block 6, lost async page write
Buffer I/O error on dev loop0, logical block 7, lost async page write
Buffer I/O error on dev loop0, logical block 8, lost async page write
Buffer I/O error on dev loop0, logical block 9, lost async page write
INFO: task syz-executor0:16435 blocked for more than 120 seconds.
      Not tainted 4.9.94-g8683408 #3
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor0   D27864 16435   3822 0x20020004
 ffff8801ba441800 0000000000000000 ffff8801b964af40 ffffffff84429800
 ffff8801db221b98 ffff8801b7dbf650 ffffffff838c040d 0000000041b58ab3
 ffffffff841a49d8 ffffffff81234350 00ffffff81463340 ffff8801db222468
Call Trace:
 [<ffffffff838c1a0f>] schedule+0x7f/0x1b0 kernel/sched/core.c:3557
 [<ffffffff838cde21>] schedule_timeout+0x861/0xf70 kernel/time/timer.c:1768
 [<ffffffff838bfbea>] io_schedule_timeout+0x1ba/0x390 kernel/sched/core.c:5180
 [<ffffffff838c2e59>] io_schedule include/linux/sched.h:460 [inline]
 [<ffffffff838c2e59>] bit_wait_io+0x19/0xa0 kernel/sched/wait.c:582
 [<ffffffff838c25a3>] __wait_on_bit+0x93/0x120 kernel/sched/wait.c:383
 [<ffffffff81431d70>] wait_on_page_bit+0x130/0x140 mm/filemap.c:802
 [<ffffffff81431f41>] wait_on_page_writeback include/linux/pagemap.h:526 [inline]
 [<ffffffff81431f41>] __filemap_fdatawait_range+0x1c1/0x290 mm/filemap.c:453
 [<ffffffff81432035>] filemap_fdatawait_range+0x25/0x50 mm/filemap.c:483
 [<ffffffff8143ad75>] filemap_write_and_wait_range+0x85/0xb0 mm/filemap.c:584
 [<ffffffff8162c6d6>] blkdev_fsync+0x66/0xb0 fs/block_dev.c:369
 [<ffffffff81617cfc>] vfs_fsync_range+0x10c/0x260 fs/sync.c:195
 [<ffffffff81630de9>] generic_write_sync include/linux/fs.h:2607 [inline]
 [<ffffffff81630de9>] blkdev_write_iter+0x2a9/0x370 fs/block_dev.c:1720
 [<ffffffff8156c3a0>] new_sync_write fs/read_write.c:496 [inline]
 [<ffffffff8156c3a0>] __vfs_write+0x3e0/0x580 fs/read_write.c:509
 [<ffffffff81570197>] vfs_write+0x187/0x530 fs/read_write.c:557
 [<ffffffff81573fc9>] SYSC_write fs/read_write.c:604 [inline]
 [<ffffffff81573fc9>] SyS_write+0xd9/0x1c0 fs/read_write.c:596
 [<ffffffff81006da7>] do_syscall_32_irqs_on arch/x86/entry/common.c:325 [inline]
 [<ffffffff81006da7>] do_fast_syscall_32+0x2f7/0x870 arch/x86/entry/common.c:387
 [<ffffffff838d2a10>] entry_SYSENTER_compat+0x90/0xa2 arch/x86/entry/entry_64_compat.S:137

Showing all locks held in the system:
2 locks held by khungtaskd/515:
 #0:  (rcu_read_lock){......}, at: [<ffffffff813646bc>] check_hung_uninterruptible_tasks kernel/hung_task.c:168 [inline]
 #0:  (rcu_read_lock){......}, at: [<ffffffff813646bc>] watchdog+0x11c/0xa20 kernel/hung_task.c:239
 #1:  (tasklist_lock){.+.+..}, at: [<ffffffff81423bb0>] debug_show_all_locks+0x79/0x218 kernel/locking/lockdep.c:4336
1 lock held by rsyslogd/3647:
 #0:  (&f->f_pos_lock){+.+.+.}, at: [<ffffffff815d565c>] __fdget_pos+0xac/0xd0 fs/file.c:781
2 locks held by getty/3743:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff838cf4b2>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+.+.}, at: [<ffffffff82007082>] n_tty_read+0x202/0x16b0 drivers/tty/n_tty.c:2133
3 locks held by kworker/u4:7/7132:
 #0:  ("writeback"){++++.+}, at: [<ffffffff8118ad0e>] work_static include/linux/workqueue.h:186 [inline]
 #0:  ("writeback"){++++.+}, at: [<ffffffff8118ad0e>] set_work_data kernel/workqueue.c:617 [inline]
 #0:  ("writeback"){++++.+}, at: [<ffffffff8118ad0e>] set_work_pool_and_clear_pending kernel/workqueue.c:644 [inline]
 #0:  ("writeback"){++++.+}, at: [<ffffffff8118ad0e>] process_one_work+0x6ee/0x1500 kernel/workqueue.c:2085
 #1:  ((&(&wb->dwork)->work)){+.+.+.}, at: [<ffffffff8118ad48>] process_one_work+0x728/0x1500 kernel/workqueue.c:2089
 #2:  (&type->s_umount_key#29){.+.+..}, at: [<ffffffff81579e90>] trylock_super+0x20/0xf0 fs/super.c:393

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

NMI backtrace for cpu 1
CPU: 1 PID: 515 Comm: khungtaskd Not tainted 4.9.94-g8683408 #3
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801d871fd08 ffffffff81d9b509 0000000000000000 0000000000000001
 0000000000000001 0000000000000001 ffffffff810b7d60 ffff8801d871fd40
 ffffffff81da6837 0000000000000001 0000000000000000 0000000000000002
Call Trace:
 [<ffffffff81d9b509>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81d9b509>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff81da6837>] nmi_cpu_backtrace.cold.2+0x48/0x87 lib/nmi_backtrace.c:99
 [<ffffffff81da67ca>] nmi_trigger_cpumask_backtrace+0x12a/0x14f lib/nmi_backtrace.c:60
 [<ffffffff810b7e64>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37
 [<ffffffff81364c54>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline]
 [<ffffffff81364c54>] check_hung_task kernel/hung_task.c:125 [inline]
 [<ffffffff81364c54>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline]
 [<ffffffff81364c54>] watchdog+0x6b4/0xa20 kernel/hung_task.c:239
 [<ffffffff8119ad2d>] kthread+0x26d/0x300 kernel/kthread.c:211
 [<ffffffff838d14dc>] 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: 18368 Comm: ipvs-m:1:0 Not tainted 4.9.94-g8683408 #3
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8801a7551800 task.stack: ffff8801a6be0000
RIP: 0010:[<ffffffff8123492b>] 
c [<ffffffff8123492b>] mark_irqflags kernel/locking/lockdep.c:2953 [inline]
RIP: 0010:[<ffffffff8123492b>] 
c [<ffffffff8123492b>] __lock_acquire+0x5db/0x4070 kernel/locking/lockdep.c:3302
RSP: 0018:ffff8801a6be7850  EFLAGS: 00000046
RAX: 0000000000000000 RBX: ffff8801a75520c8 RCX: ffff8801a75520e9
RDX: 1ffff10034eaa509 RSI: 0000000000000002 RDI: ffff8801a7552848
RBP: ffff8801a6be7a00 R08: 0000000000000001 R09: 0000000000000001
R10: ffff8801a7551800 R11: 0000000000000001 R12: 0000000000000022
R13: 0000000000000000 R14: 0000000000000000 R15: ffff8801a75520ea
FS:  0000000000000000(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000c420009e80 CR3: 00000001b9fd4000 CR4: 0000000000160670
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 0000000000000000
c 1ffff10034d7cf19
c 0000000200000001
c ffff8801db318558
c
 0000000000000000
c ffff880100000000
c ffff8801d9acd680
c ffff8801a7552108
c
 ffff8801a75520b8
c ffff8801a7552110
c ffff8801a75520c0
c ffff8801a75520c8
c
Call Trace:
 [<ffffffff81238e30>] lock_acquire+0x130/0x3e0 kernel/locking/lockdep.c:3756
 [<ffffffff811b8a55>] finish_lock_switch kernel/sched/sched.h:1210 [inline]
 [<ffffffff811b8a55>] finish_task_switch+0x1e5/0x640 kernel/sched/core.c:2825
 [<ffffffff838c0415>] context_switch kernel/sched/core.c:2958 [inline]
 [<ffffffff838c0415>] __schedule+0x655/0x1bd0 kernel/sched/core.c:3502
 [<ffffffff838c1a0f>] schedule+0x7f/0x1b0 kernel/sched/core.c:3557
 [<ffffffff838cda4b>] schedule_timeout+0x48b/0xf70 kernel/time/timer.c:1791
 [<ffffffff838aac86>] sync_thread_master+0x272/0x6e3 net/netfilter/ipvs/ip_vs_sync.c:1703
 [<ffffffff8119ad2d>] kthread+0x26d/0x300 kernel/kthread.c:211
 [<ffffffff838d14dc>] ret_from_fork+0x5c/0x70 arch/x86/entry/entry_64.S:373
Code: 
c00 
c00 
c48 
cb8 
c00 
c00 
c00 
c00 
c00 
cfc 
cff 
cdf 
c48 
c89 
cfa 
c48 
cc1 
cea 
c03 
c0f 
cb6 
c04 
c02 
c84 
cc0 
c74 
c08 
c3c 
c03 
c0f 
c8e 
cd6 
c2e 
c00 
c00 
c41 
cf6 
c82 
c48 
c10 
c00 
c00 
c80 
c<74> 
c62 
c48 
cb8 
c00 
c00 
c00 
c00 
c00 
cfc 
cff 
cdf 
c4c 
c89 
cfa 
c48 
cc1 
cea 
c03 
c0f 
cb6 
c