Buffer I/O error on dev loop7, logical block 5, lost async page write
INFO: task syz-executor1:22219 blocked for more than 140 seconds.
      Not tainted 4.9.118-g47b77b8 #20
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor1   D28488 22219   3864 0x00000004
 ffff8801d3803000 ffff8801cec4d500 ffff8801d704b480 ffff88019a518000
 ffff8801db221c18 ffff8801cf0c7a38 ffffffff839ebbad ffffffff81235627
 0000000000000000 ffff8801d38038c0 0000000600000007 ffff8801db2224e8
Call Trace:
 [<ffffffff839ed1af>] schedule+0x7f/0x1b0 kernel/sched/core.c:3553
 [<ffffffff839f87e8>] __rwsem_down_write_failed_common kernel/locking/rwsem-xadd.c:526 [inline]
 [<ffffffff839f87e8>] rwsem_down_write_failed+0x598/0x990 kernel/locking/rwsem-xadd.c:555
 [<ffffffff81ee8e67>] call_rwsem_down_write_failed+0x17/0x30 arch/x86/lib/rwsem.S:105
 [<ffffffff839f65bc>] __down_write arch/x86/include/asm/rwsem.h:125 [inline]
 [<ffffffff839f65bc>] down_write+0x5c/0xa0 kernel/locking/rwsem.c:54
 [<ffffffff815e1bfc>] inode_lock include/linux/fs.h:766 [inline]
 [<ffffffff815e1bfc>] lock_mount+0x8c/0x2c0 fs/namespace.c:2077
 [<ffffffff815e49c7>] do_add_mount+0x27/0x340 fs/namespace.c:2460
 [<ffffffff815e66b2>] do_new_mount fs/namespace.c:2527 [inline]
 [<ffffffff815e66b2>] do_mount+0x1332/0x2740 fs/namespace.c:2835
 [<ffffffff815e849e>] SYSC_mount fs/namespace.c:3051 [inline]
 [<ffffffff815e849e>] SyS_mount+0xfe/0x110 fs/namespace.c:3028
 [<ffffffff81006316>] do_syscall_64+0x1a6/0x490 arch/x86/entry/common.c:282
 [<ffffffff839fca93>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb

Showing all locks held in the system:
2 locks held by khungtaskd/519:
 #0:  (rcu_read_lock){......}, at: [<ffffffff8136679c>] check_hung_uninterruptible_tasks kernel/hung_task.c:168 [inline]
 #0:  (rcu_read_lock){......}, at: [<ffffffff8136679c>] watchdog+0x11c/0xa20 kernel/hung_task.c:239
 #1:  (tasklist_lock){.+.+..}, at: [<ffffffff81425fb7>] debug_show_all_locks+0x79/0x218 kernel/locking/lockdep.c:4336
2 locks held by rs:main Q:Reg/3664:
 #0:  (&f->f_pos_lock){+.+.+.}, at: [<ffffffff815d853c>] __fdget_pos+0xac/0xd0 fs/file.c:781
 #1:  (sb_writers#3){.+.+.+}, at: [<ffffffff8157301e>] file_start_write include/linux/fs.h:2640 [inline]
 #1:  (sb_writers#3){.+.+.+}, at: [<ffffffff8157301e>] vfs_write+0x3ae/0x530 fs/read_write.c:556
2 locks held by getty/3762:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff839fac52>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+.+.}, at: [<ffffffff821207a2>] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2142
1 lock held by syz-executor1/22171:
 #0:  (&sb->s_type->i_mutex_key#22){++++++}, at: [<ffffffff81595001>] inode_lock_shared include/linux/fs.h:776 [inline]
 #0:  (&sb->s_type->i_mutex_key#22){++++++}, at: [<ffffffff81595001>] lookup_slow+0x141/0x470 fs/namei.c:1645
1 lock held by syz-executor1/22219:
 #0:  (&sb->s_type->i_mutex_key#22){++++++}, at: [<ffffffff815e1bfc>] inode_lock include/linux/fs.h:766 [inline]
 #0:  (&sb->s_type->i_mutex_key#22){++++++}, at: [<ffffffff815e1bfc>] lock_mount+0x8c/0x2c0 fs/namespace.c:2077

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

NMI backtrace for cpu 0
CPU: 0 PID: 519 Comm: khungtaskd Not tainted 4.9.118-g47b77b8 #20
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801d85dfd08 ffffffff81eb4b89 0000000000000000 0000000000000000
 0000000000000000 0000000000000001 ffffffff810b9bd0 ffff8801d85dfd40
 ffffffff81ebfe87 0000000000000000 0000000000000000 0000000000000003
Call Trace:
 [<ffffffff81eb4b89>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81eb4b89>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff81ebfe87>] nmi_cpu_backtrace.cold.2+0x48/0x87 lib/nmi_backtrace.c:99
 [<ffffffff81ebfe1a>] nmi_trigger_cpumask_backtrace+0x12a/0x14f lib/nmi_backtrace.c:60
 [<ffffffff810b9cd4>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37
 [<ffffffff81366d34>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline]
 [<ffffffff81366d34>] check_hung_task kernel/hung_task.c:125 [inline]
 [<ffffffff81366d34>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline]
 [<ffffffff81366d34>] watchdog+0x6b4/0xa20 kernel/hung_task.c:239
 [<ffffffff8119d0ed>] kthread+0x26d/0x300 kernel/kthread.c:211
 [<ffffffff839fcc5c>] ret_from_fork+0x5c/0x70 arch/x86/entry/entry_64.S:373
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.9.118-g47b77b8 #20
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8801d9a6b000 task.stack: ffff8801d9a80000
RIP: 0010:[<ffffffff81236213>] 
c [<ffffffff81236213>] __lock_acquire+0x83/0x4070 kernel/locking/lockdep.c:3204
RSP: 0018:ffff8801db307ae0  EFLAGS: 00000082
RAX: ffffed003b660f70 RBX: 0000000000000046 RCX: 0000000000000000
RDX: dffffc0000000000 RSI: 0000000000000000 RDI: ffff8801db321c18
RBP: ffff8801db307c90 R08: 0000000000000001 R09: 0000000000000001
R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801d9a6b000
R13: 0000000000000000 R14: ffff8801db321c18 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f39efda8000 CR3: 00000001bfa9d000 CR4: 00000000001606f0
DR0: 0000000020000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Stack:
 ffff8801d9a6b000
c ffffffff846def20
c ffff8801ba4be280
c 0000000000000001
c
 ffff8801db307b28
c 0000000000000046
c 0000000000000003
c ffff8801db321ca0
c
 ffff8801ba4be270
c ffff8801db307b40
c ffffffff8127c163
c ffff8801d9a6b8c8
c
Call Trace:
 [<ffffffff8123ac70>] lock_acquire+0x130/0x3e0 kernel/locking/lockdep.c:3756
 [<ffffffff839fc9ce>] __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:112 [inline]
 [<ffffffff839fc9ce>] _raw_spin_lock_irqsave+0x4e/0x62 kernel/locking/spinlock.c:159
 [<ffffffff811f2302>] update_blocked_averages+0x52/0x520 kernel/sched/fair.c:8188
 [<ffffffff81207c34>] rebalance_domains+0xe4/0xbc0 kernel/sched/fair.c:10076
 [<ffffffff81208a09>] run_rebalance_domains+0x2f9/0x510 kernel/sched/fair.c:10333
 [<ffffffff83a0367b>] __do_softirq+0x20b/0x937 kernel/softirq.c:284
 [<ffffffff8114b277>] invoke_softirq kernel/softirq.c:364 [inline]
 [<ffffffff8114b277>] irq_exit+0x147/0x190 kernel/softirq.c:405
 [<ffffffff83a01221>] smp_reschedule_interrupt+0x71/0x90 arch/x86/kernel/smp.c:270
 [<ffffffff839fed90>] reschedule_interrupt+0xa0/0xb0 arch/x86/entry/entry_64.S:671
 <EOI> 
d [<ffffffff839fb6b6>] ? native_safe_halt+0x6/0x10 arch/x86/include/asm/irqflags.h:53
 [<ffffffff839facf5>] arch_safe_halt arch/x86/include/asm/paravirt.h:104 [inline]
 [<ffffffff839facf5>] default_idle+0x55/0x360 arch/x86/kernel/process.c:437
 [<ffffffff8106ae20>] arch_cpu_idle+0x10/0x20 arch/x86/kernel/process.c:428
 [<ffffffff839fbb15>] default_idle_call+0x45/0x60 kernel/sched/idle.c:97
 [<ffffffff812231b5>] cpuidle_idle_call kernel/sched/idle.c:155 [inline]
 [<ffffffff812231b5>] cpu_idle_loop kernel/sched/idle.c:248 [inline]
 [<ffffffff812231b5>] cpu_startup_entry+0x2b5/0x380 kernel/sched/idle.c:303
 [<ffffffff810aefa8>] start_secondary+0x328/0x400 arch/x86/kernel/smpboot.c:257
Code: 
c48 
c8d 
c84 
c24 
ca0 
c00 
c00 
c00 
c48 
cc1 
ce8 
c03 
c48 
c89 
c84 
c24 
c90 
c00 
c00 
c00 
c48 
c01 
cd0 
cc7 
c00 
cf1 
cf1 
cf1 
cf1 
cc7 
c40 
c04 
c00 
cf2 
cf2 
cf2 
cc7 
c40 
c08 
cf2 
cf2 
cf2 
cf2 
c<c7> 
c40 
c14 
cf3 
cf3 
cf3 
cf3 
c65 
c48 
c8b 
c04 
c25 
c28 
c00 
c00 
c00 
c48 
c89 
c84 
c24 
c78 
c