Buffer I/O error on dev loop0, logical block 3, async page read
Buffer I/O error on dev loop0, logical block 1, lost async page write
Buffer I/O error on dev loop0, logical block 2, lost async page write
Buffer I/O error on dev loop0, logical block 3, lost async page write
INFO: task syz-executor0:19515 blocked for more than 120 seconds.
      Not tainted 4.9.86-gb324a70 #50
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor0   D26760 19515  15063 0x00000004
 ffff8801d4f43000 0000000000000000 ffff8801d7684000 ffffffff84429880
 ffff8801db221b98 ffff8801d56bf270 ffffffff838a457b 0000000041b58ab3
 ffffffff84193a48 00ffffff8123c030 ffff8801db222468 ffff8801db222490
Call Trace:
 [<ffffffff838a5b1f>] schedule+0x7f/0x1b0 kernel/sched/core.c:3550
 [<ffffffff838b1c7c>] schedule_timeout+0x56c/0x10b0 kernel/time/timer.c:1768
 [<ffffffff838a3d2e>] io_schedule_timeout+0x1be/0x390 kernel/sched/core.c:5172
 [<ffffffff838a6f99>] io_schedule include/linux/sched.h:460 [inline]
 [<ffffffff838a6f99>] bit_wait_io+0x19/0xa0 kernel/sched/wait.c:582
 [<ffffffff838a6677>] __wait_on_bit+0x57/0x120 kernel/sched/wait.c:383
 [<ffffffff814325c4>] wait_on_page_bit+0xf4/0x140 mm/filemap.c:802
 [<ffffffff814327d1>] wait_on_page_writeback include/linux/pagemap.h:526 [inline]
 [<ffffffff814327d1>] __filemap_fdatawait_range+0x1c1/0x2b0 mm/filemap.c:453
 [<ffffffff814328e5>] filemap_fdatawait_range+0x25/0x50 mm/filemap.c:483
 [<ffffffff8143b624>] filemap_write_and_wait_range+0x74/0xb0 mm/filemap.c:584
 [<ffffffff8162a956>] blkdev_fsync+0x66/0xb0 fs/block_dev.c:369
 [<ffffffff816162aa>] vfs_fsync_range+0x10a/0x250 fs/sync.c:195
 [<ffffffff8162d526>] generic_write_sync include/linux/fs.h:2589 [inline]
 [<ffffffff8162d526>] blkdev_write_iter+0x2a6/0x380 fs/block_dev.c:1720
 [<ffffffff8156df30>] vfs_iter_write+0x2e0/0x450 fs/read_write.c:390
 [<ffffffff81613225>] iter_file_splice_write+0x5b5/0xb60 fs/splice.c:768
 [<ffffffff8160e065>] do_splice_from fs/splice.c:870 [inline]
 [<ffffffff8160e065>] direct_splice_actor+0x125/0x180 fs/splice.c:1037
 [<ffffffff8160f62c>] splice_direct_to_actor+0x2cc/0x800 fs/splice.c:992
 [<ffffffff8160fd07>] do_splice_direct+0x1a7/0x270 fs/splice.c:1080
 [<ffffffff81572c4b>] do_sendfile+0x54b/0xd30 fs/read_write.c:1393
 [<ffffffff81574ba1>] SYSC_sendfile64 fs/read_write.c:1448 [inline]
 [<ffffffff81574ba1>] SyS_sendfile64+0xd1/0x160 fs/read_write.c:1440
 [<ffffffff81006504>] do_syscall_64+0x1a4/0x490 arch/x86/entry/common.c:282
 [<ffffffff838b5613>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb

Showing all locks held in the system:
2 locks held by khungtaskd/515:
 #0:  (rcu_read_lock){......}, at: [<ffffffff81373065>] check_hung_uninterruptible_tasks kernel/hung_task.c:168 [inline]
 #0:  (rcu_read_lock){......}, at: [<ffffffff81373065>] watchdog+0x125/0xa70 kernel/hung_task.c:239
 #1:  (tasklist_lock){.+.+..}, at: [<ffffffff81238190>] debug_show_all_locks+0x70/0x280 kernel/locking/lockdep.c:4336
1 lock held by rsyslogd/3510:
 #0:  (&f->f_pos_lock){+.+.+.}, at: [<ffffffff815d3c2f>] __fdget_pos+0x9f/0xc0 fs/file.c:781
2 locks held by getty/3637:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff838b37f2>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+.+.}, at: [<ffffffff8200abe4>] n_tty_read+0x1f4/0x16c0 drivers/tty/n_tty.c:2133
3 locks held by kworker/u4:10/9983:
 #0:  ("writeback"){++++.+}, at: [<ffffffff811897b2>] work_static include/linux/workqueue.h:186 [inline]
 #0:  ("writeback"){++++.+}, at: [<ffffffff811897b2>] set_work_data kernel/workqueue.c:617 [inline]
 #0:  ("writeback"){++++.+}, at: [<ffffffff811897b2>] set_work_pool_and_clear_pending kernel/workqueue.c:644 [inline]
 #0:  ("writeback"){++++.+}, at: [<ffffffff811897b2>] process_one_work+0x6f2/0x1610 kernel/workqueue.c:2085
 #1:  ((&(&wb->dwork)->work)){+.+.+.}, at: [<ffffffff811897ec>] process_one_work+0x72c/0x1610 kernel/workqueue.c:2089
 #2:  (&type->s_umount_key#22){.+.+..}, at: [<ffffffff81579ce0>] trylock_super+0x20/0x100 fs/super.c:393

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

NMI backtrace for cpu 1
CPU: 1 PID: 515 Comm: khungtaskd Not tainted 4.9.86-gb324a70 #50
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801d8a37d00 ffffffff81d956f9 0000000000000000 0000000000000001
 0000000000000001 0000000000000001 ffffffff810bb190 ffff8801d8a37d38
 ffffffff81da081d 0000000000000001 0000000000000000 ffff8801c402e418
Call Trace:
 [<ffffffff81d956f9>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81d956f9>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff81da081d>] nmi_cpu_backtrace+0xfd/0x120 lib/nmi_backtrace.c:99
 [<ffffffff81da0957>] nmi_trigger_cpumask_backtrace+0x117/0x190 lib/nmi_backtrace.c:60
 [<ffffffff810bb284>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37
 [<ffffffff81373630>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline]
 [<ffffffff81373630>] check_hung_task kernel/hung_task.c:125 [inline]
 [<ffffffff81373630>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline]
 [<ffffffff81373630>] watchdog+0x6f0/0xa70 kernel/hung_task.c:239
 [<ffffffff8119a7bd>] kthread+0x26d/0x300 kernel/kthread.c:211
 [<ffffffff838b57ac>] ret_from_fork+0x5c/0x70 arch/x86/entry/entry_64.S:374
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0 skipped: idling at pc 0xffffffff838b4266