INFO: task syz-executor4:1802 blocked for more than 140 seconds.
      Not tainted 4.9.113-g9905591 #14
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor4   D26800  1802  15260 0x00000004
 ffff8801ce12b000 ffff8801aa46f9c0 ffff8801d4fbb480 ffff8801a3f28000
 ffff8801db221c18 ffff8801be14f650 ffffffff839e929d dffffc0000000000
 ffff8801b72deab0 ffff8801be14f610 00ff8801ce12b8c0 ffff8801db2224e8
Call Trace:
 [<ffffffff839ea89f>] schedule+0x7f/0x1b0 kernel/sched/core.c:3553
 [<ffffffff815c7d52>] d_wait_lookup fs/dcache.c:2455 [inline]
 [<ffffffff815c7d52>] d_alloc_parallel+0xeb2/0x17c0 fs/dcache.c:2537
 [<ffffffff81594d0c>] lookup_slow+0x19c/0x470 fs/namei.c:1650
 [<ffffffff815a1336>] walk_component+0x716/0x1bb0 fs/namei.c:1784
 [<ffffffff815a3c96>] lookup_last fs/namei.c:2266 [inline]
 [<ffffffff815a3c96>] path_lookupat.isra.41+0x186/0x410 fs/namei.c:2283
 [<ffffffff815a9747>] filename_lookup.part.55+0x177/0x370 fs/namei.c:2317
 [<ffffffff815a9b03>] filename_lookup fs/namei.c:2310 [inline]
 [<ffffffff815a9b03>] user_path_at_empty+0x53/0x70 fs/namei.c:2578
 [<ffffffff81580ae6>] user_path_at include/linux/namei.h:55 [inline]
 [<ffffffff81580ae6>] vfs_fstatat+0xc6/0x170 fs/stat.c:106
 [<ffffffff81581c96>] vfs_stat fs/stat.c:123 [inline]
 [<ffffffff81581c96>] SYSC_newstat+0x86/0xf0 fs/stat.c:270
 [<ffffffff8158209d>] SyS_newstat+0x1d/0x30 fs/stat.c:266
 [<ffffffff81006316>] do_syscall_64+0x1a6/0x490 arch/x86/entry/common.c:282
 [<ffffffff839fa193>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb

Showing all locks held in the system:
2 locks held by khungtaskd/520:
 #0:  (rcu_read_lock){......}, at: [<ffffffff8136675c>] check_hung_uninterruptible_tasks kernel/hung_task.c:168 [inline]
 #0:  (rcu_read_lock){......}, at: [<ffffffff8136675c>] watchdog+0x11c/0xa20 kernel/hung_task.c:239
 #1:  (tasklist_lock){.+.+..}, at: [<ffffffff81425de7>] debug_show_all_locks+0x79/0x218 kernel/locking/lockdep.c:4336
2 locks held by getty/3774:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff839f8342>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+.+.}, at: [<ffffffff8211ee22>] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2142
1 lock held by syz-executor4/1802:
 #0:  (&type->i_mutex_dir_key#4){++++++}, at: [<ffffffff81594cb1>] inode_lock_shared include/linux/fs.h:776 [inline]
 #0:  (&type->i_mutex_dir_key#4){++++++}, at: [<ffffffff81594cb1>] lookup_slow+0x141/0x470 fs/namei.c:1645

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

NMI backtrace for cpu 0
CPU: 0 PID: 520 Comm: khungtaskd Not tainted 4.9.113-g9905591 #14
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801d8b2fd08 ffffffff81eb32a9 0000000000000000 0000000000000000
 0000000000000000 0000000000000001 ffffffff810b9bd0 ffff8801d8b2fd40
 ffffffff81ebe5a7 0000000000000000 0000000000000000 0000000000000003
Call Trace:
 [<ffffffff81eb32a9>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81eb32a9>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff81ebe5a7>] nmi_cpu_backtrace.cold.2+0x48/0x87 lib/nmi_backtrace.c:99
 [<ffffffff81ebe53a>] 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
 [<ffffffff81366cf4>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline]
 [<ffffffff81366cf4>] check_hung_task kernel/hung_task.c:125 [inline]
 [<ffffffff81366cf4>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline]
 [<ffffffff81366cf4>] watchdog+0x6b4/0xa20 kernel/hung_task.c:239
 [<ffffffff8119d0ad>] kthread+0x26d/0x300 kernel/kthread.c:211
 [<ffffffff839fa35c>] 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: 1849 Comm: syz-executor4 Not tainted 4.9.113-g9905591 #14
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8801cf659800 task.stack: ffff8801a2af0000
RIP: 0010:[<ffffffff811bbec0>] 
c [<ffffffff811bbec0>] preempt_count_add+0x0/0x170 include/linux/rcupdate.h:878
RSP: 0018:ffff8801a2af7380  EFLAGS: 00000046
RAX: 0000000000000007 RBX: ffff88019a4b4560 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000001
RBP: ffff8801a2af73a0 R08: ffff8801cf65a110 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000296
R13: ffff8801a2af74a8 R14: ffff88019a4b4560 R15: 0000000000000001
FS:  00007fbe4bf2b700(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fab936f8000 CR3: 00000001d390a000 CR4: 00000000001606f0
DR0: 0000000020000000 DR1: 0000000020000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600
Stack:
 ffffffff839fa09e
c 0000000000000246
c 1ffff1003455ee79
c ffff8801a2af7428
c
 ffff8801a2af7450
c ffffffff812215bb
c ffff8801a2af73d8
c 0000000000000246
c
 ffff8801cf659800
c 0000000041b58ab3
c ffffffff843bbae3
c ffffffff81221550
c
Call Trace:
 [<ffffffff812215bb>] prepare_to_wait_event+0x6b/0x450 kernel/sched/wait.c:213
 [<ffffffff81907bbe>] request_wait_answer+0x22e/0x6e0 fs/fuse/dev.c:459
 [<ffffffff819086c9>] __fuse_request_send+0x109/0x1b0 fs/fuse/dev.c:480
 [<ffffffff819087cd>] fuse_request_send+0x5d/0x70 fs/fuse/dev.c:493
 [<ffffffff81912a24>] fuse_simple_request+0x2f4/0x660 fs/fuse/dev.c:551
 [<ffffffff8191adc3>] fuse_lookup_name+0x253/0x5d0 fs/fuse/dir.c:369
 [<ffffffff8191b22d>] fuse_lookup+0xed/0x3a0 fs/fuse/dir.c:406
 [<ffffffff81594dae>] lookup_slow+0x23e/0x470 fs/namei.c:1668
 [<ffffffff815a1336>] walk_component+0x716/0x1bb0 fs/namei.c:1784
 [<ffffffff815a3c96>] lookup_last fs/namei.c:2266 [inline]
 [<ffffffff815a3c96>] path_lookupat.isra.41+0x186/0x410 fs/namei.c:2283
 [<ffffffff815a9747>] filename_lookup.part.55+0x177/0x370 fs/namei.c:2317
 [<ffffffff815a9b03>] filename_lookup fs/namei.c:2310 [inline]
 [<ffffffff815a9b03>] user_path_at_empty+0x53/0x70 fs/namei.c:2578
 [<ffffffff815e5164>] user_path include/linux/namei.h:60 [inline]
 [<ffffffff815e5164>] do_mount+0x134/0x2740 fs/namespace.c:2780
 [<ffffffff815e814e>] SYSC_mount fs/namespace.c:3051 [inline]
 [<ffffffff815e814e>] SyS_mount+0xfe/0x110 fs/namespace.c:3028
 [<ffffffff81006316>] do_syscall_64+0x1a6/0x490 arch/x86/entry/common.c:282
 [<ffffffff839fa193>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb
Code: 
c97 
c37 
c0c 
c00 
c84 
cc0 
c75 
cf5 
c48 
cc7 
cc2 
c40 
c77 
cc5 
c83 
cbe 
c6d 
c03 
c00 
c00 
c48 
cc7 
cc7 
c00 
c70 
cc5 
c83 
cc6 
c05 
c8b 
cf0 
ca8 
c03 
c01 
ce8 
cd4 
c73 
c07 
c00 
cc9 
cc3 
c66 
c90 
c<48> 
cb8 
c00 
c00 
c00 
c00 
c00 
cfc 
cff 
cdf 
c55 
c48 
c89 
ce5 
c41 
c54 
c53 
c89 
cfb 
c48 
cc7 
c