Buffer I/O error on dev loop0, logical block 10, lost async page write
INFO: task syz-executor7:7873 blocked for more than 120 seconds.
      Not tainted 4.9.90-gdd1e37e #66
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor7   D27616  7873  13209 0x00000004
 ffff8801caede000 ffff8801bbd9df80 ffff8801bbd9df80 ffff8801b1401800
 ffff8801db321b98 ffff8801cd4ef940 ffffffff838a75cb 0000000041b58ab3
 ffffffff84193d90 00ffffff8123aaf0 ffff8801db322468 ffff8801db322490
Call Trace:
 [<ffffffff838a8b6f>] schedule+0x7f/0x1b0 kernel/sched/core.c:3551
 [<ffffffff838b4b2c>] schedule_timeout+0x56c/0x10b0 kernel/time/timer.c:1768
 [<ffffffff838a6d7e>] io_schedule_timeout+0x1be/0x390 kernel/sched/core.c:5173
 [<ffffffff838a9fe9>] io_schedule include/linux/sched.h:460 [inline]
 [<ffffffff838a9fe9>] bit_wait_io+0x19/0xa0 kernel/sched/wait.c:582
 [<ffffffff838a96c7>] __wait_on_bit+0x57/0x120 kernel/sched/wait.c:383
 [<ffffffff814316e4>] wait_on_page_bit+0xf4/0x140 mm/filemap.c:802
 [<ffffffff814318f1>] wait_on_page_writeback include/linux/pagemap.h:526 [inline]
 [<ffffffff814318f1>] __filemap_fdatawait_range+0x1c1/0x2b0 mm/filemap.c:453
 [<ffffffff8143b853>] filemap_fdatawait_keep_errors+0x63/0x80 mm/filemap.c:511
 [<ffffffff81615340>] fdatawait_one_bdev+0x50/0x70 fs/sync.c:94
 [<ffffffff816309f9>] iterate_bdevs+0x109/0x260 fs/block_dev.c:1978
 [<ffffffff81615c11>] sys_sync+0xe1/0x170 fs/sync.c:116
 [<ffffffff81006504>] do_syscall_64+0x1a4/0x490 arch/x86/entry/common.c:282
 [<ffffffff838b8493>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb

Showing all locks held in the system:
2 locks held by khungtaskd/516:
 #0:  (rcu_read_lock){......}, at: [<ffffffff81372185>] check_hung_uninterruptible_tasks kernel/hung_task.c:168 [inline]
 #0:  (rcu_read_lock){......}, at: [<ffffffff81372185>] watchdog+0x125/0xa70 kernel/hung_task.c:239
 #1:  (tasklist_lock){.+.+..}, at: [<ffffffff81236c50>] debug_show_all_locks+0x70/0x280 kernel/locking/lockdep.c:4336
1 lock held by rsyslogd/3655:
 #0:  (&f->f_pos_lock){+.+.+.}, at: [<ffffffff815d2f5f>] __fdget_pos+0x9f/0xc0 fs/file.c:781
2 locks held by getty/3783:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff838b66a2>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+.+.}, at: [<ffffffff8200a6a4>] n_tty_read+0x1f4/0x16c0 drivers/tty/n_tty.c:2133
3 locks held by kworker/u4:5/7020:
 #0:  ("writeback"){++++.+}, at: [<ffffffff8118af42>] work_static include/linux/workqueue.h:186 [inline]
 #0:  ("writeback"){++++.+}, at: [<ffffffff8118af42>] set_work_data kernel/workqueue.c:617 [inline]
 #0:  ("writeback"){++++.+}, at: [<ffffffff8118af42>] set_work_pool_and_clear_pending kernel/workqueue.c:644 [inline]
 #0:  ("writeback"){++++.+}, at: [<ffffffff8118af42>] process_one_work+0x6f2/0x1610 kernel/workqueue.c:2085
 #1:  ((&(&wb->dwork)->work)){+.+.+.}, at: [<ffffffff8118af7c>] process_one_work+0x72c/0x1610 kernel/workqueue.c:2089
 #2:  (&type->s_umount_key#22){.+.+..}, at: [<ffffffff815790a0>] trylock_super+0x20/0x100 fs/super.c:393
1 lock held by syz-executor7/7873:
 #0:  (&bdev->bd_mutex){+.+.+.}, at: [<ffffffff816309b8>] iterate_bdevs+0xc8/0x260 fs/block_dev.c:1976
1 lock held by syz-executor7/7881:
 #0:  (&bdev->bd_mutex){+.+.+.}, at: [<ffffffff8162d90c>] __blkdev_get+0x10c/0xd50 fs/block_dev.c:1268
1 lock held by syz-executor7/7882:
 #0:  (&bdev->bd_mutex){+.+.+.}, at: [<ffffffff816309b8>] iterate_bdevs+0xc8/0x260 fs/block_dev.c:1976
1 lock held by blkid/7880:
 #0:  (&bdev->bd_mutex){+.+.+.}, at: [<ffffffff8162e57a>] blkdev_put+0x2a/0x550 fs/block_dev.c:1621

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

NMI backtrace for cpu 1
CPU: 1 PID: 516 Comm: khungtaskd Not tainted 4.9.90-gdd1e37e #66
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801d966fd00 ffffffff81d94ee9 0000000000000000 0000000000000001
 0000000000000001 0000000000000001 ffffffff810bb920 ffff8801d966fd38
 ffffffff81da000d 0000000000000001 0000000000000000 ffff8801cbd13418
Call Trace:
 [<ffffffff81d94ee9>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81d94ee9>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff81da000d>] nmi_cpu_backtrace+0xfd/0x120 lib/nmi_backtrace.c:99
 [<ffffffff81da0147>] nmi_trigger_cpumask_backtrace+0x117/0x190 lib/nmi_backtrace.c:60
 [<ffffffff810bba14>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37
 [<ffffffff81372750>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline]
 [<ffffffff81372750>] check_hung_task kernel/hung_task.c:125 [inline]
 [<ffffffff81372750>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline]
 [<ffffffff81372750>] watchdog+0x6f0/0xa70 kernel/hung_task.c:239
 [<ffffffff8119bf4d>] kthread+0x26d/0x300 kernel/kthread.c:211
 [<ffffffff838b865c>] 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: 3653 Comm: rs:main Q:Reg Not tainted 4.9.90-gdd1e37e #66
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8801c779b000 task.stack: ffff8801b46f0000
RIP: 0010:[<ffffffff8170cf7f>] 
c [<ffffffff8170cf7f>] ext4_has_free_clusters+0x18f/0x520 fs/ext4/balloc.c:552
RSP: 0018:ffff8801b46f73a8  EFLAGS: 00000246
RAX: dffffc0000000000 RBX: 0000000000001017 RCX: 0000000000000000
RDX: 0000000000006659 RSI: 0000000000000000 RDI: ffffffff84a3a86c
RBP: ffff8801b46f73f0 R08: ffff8801ce151100 R09: 0000000000001017
R10: 0000000000000003 R11: ffff8801c779b000 R12: 0000000000000000
R13: 0000000000000001 R14: 0000000000001000 R15: ffff8801ce151100
FS:  00007fee1e2c9700(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000011a4000 CR3: 00000001c7784000 CR4: 0000000000160670
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 ffffffff00000000
c ffff8801b46f73f0
c 0000000000000000
c 0000000000000000
c
 ffff8801ce151100
c 0000000000000001
c 0000000000000000
c ffff8801af88b758
c
 ffffffffffff0000
c ffff8801b46f7418
c ffffffff8170e945
c ffff8801aacef738
c
Call Trace:
 [<ffffffff8170e945>] ext4_claim_free_clusters+0x25/0xa0 fs/ext4/balloc.c:588
 [<ffffffff817281ef>] ext4_da_reserve_space fs/ext4/inode.c:1527 [inline]
 [<ffffffff817281ef>] ext4_da_map_blocks fs/ext4/inode.c:1815 [inline]
 [<ffffffff817281ef>] ext4_da_get_block_prep+0x91f/0x1150 fs/ext4/inode.c:1888
 [<ffffffff81624f4c>] __block_write_begin_int+0x37c/0x1000 fs/buffer.c:1987
 [<ffffffff81625c00>] __block_write_begin+0x30/0x40 fs/buffer.c:2038
 [<ffffffff8174211e>] ext4_da_write_begin+0x3ee/0x1020 fs/ext4/inode.c:3004
 [<ffffffff81433471>] generic_perform_write+0x261/0x500 mm/filemap.c:2741
 [<ffffffff8143afc8>] __generic_file_write_iter+0x348/0x570 mm/filemap.c:2866
 [<ffffffff81718a5f>] ext4_file_write_iter+0x99f/0xe00 fs/ext4/file.c:165
 [<ffffffff8156ddcf>] new_sync_write fs/read_write.c:496 [inline]
 [<ffffffff8156ddcf>] __vfs_write+0x4bf/0x680 fs/read_write.c:509
 [<ffffffff8156f6f9>] vfs_write+0x189/0x530 fs/read_write.c:557
 [<ffffffff815731b9>] SYSC_write fs/read_write.c:604 [inline]
 [<ffffffff815731b9>] SyS_write+0xd9/0x1b0 fs/read_write.c:596
 [<ffffffff81006504>] do_syscall_64+0x1a4/0x490 arch/x86/entry/common.c:282
 [<ffffffff838b8493>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb
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