INFO: task syz-executor3:13682 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-executor3   D28568 13682   3896 0x00000004
 ffff8801d9aeb000 ffff8801b9c3b480 ffff8801d43bcfc0 ffff88019bbb1800
 ffff8801db221c18 ffff880199f9f650 ffffffff839ebbad dffffc0000000000
 ffff8801b623d870 ffff880199f9f610 00ff8801d9aeb8c0 ffff8801db2224e8
Call Trace:
 [<ffffffff839ed1af>] schedule+0x7f/0x1b0 kernel/sched/core.c:3553
 [<ffffffff815c80a2>] d_wait_lookup fs/dcache.c:2455 [inline]
 [<ffffffff815c80a2>] d_alloc_parallel+0xeb2/0x17c0 fs/dcache.c:2537
 [<ffffffff8159505c>] lookup_slow+0x19c/0x470 fs/namei.c:1650
 [<ffffffff815a1686>] walk_component+0x716/0x1bb0 fs/namei.c:1784
 [<ffffffff815a3fe6>] lookup_last fs/namei.c:2266 [inline]
 [<ffffffff815a3fe6>] path_lookupat.isra.41+0x186/0x410 fs/namei.c:2283
 [<ffffffff815a9a97>] filename_lookup.part.55+0x177/0x370 fs/namei.c:2317
 [<ffffffff815a9e53>] filename_lookup fs/namei.c:2310 [inline]
 [<ffffffff815a9e53>] user_path_at_empty+0x53/0x70 fs/namei.c:2578
 [<ffffffff81580e36>] user_path_at include/linux/namei.h:55 [inline]
 [<ffffffff81580e36>] vfs_fstatat+0xc6/0x170 fs/stat.c:106
 [<ffffffff815820d9>] vfs_lstat fs/stat.c:129 [inline]
 [<ffffffff815820d9>] SYSC_newlstat+0x89/0x100 fs/stat.c:283
 [<ffffffff8158241d>] SyS_newlstat+0x1d/0x30 fs/stat.c:277
 [<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/520:
 #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/3677:
 #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/3775:
 #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-executor3/13673:
 #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-executor3/13682:
 #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-executor3/13751:
 #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-executor3/13752:
 #0:  (&type->s_umount_key#52/1){+.+.+.}, at: [<ffffffff8157bd42>] alloc_super fs/super.c:241 [inline]
 #0:  (&type->s_umount_key#52/1){+.+.+.}, at: [<ffffffff8157bd42>] sget_userns+0x552/0xba0 fs/super.c:503

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

NMI backtrace for cpu 1
CPU: 1 PID: 520 Comm: khungtaskd Not tainted 4.9.118-g47b77b8 #20
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801d89cfd08 ffffffff81eb4b89 0000000000000000 0000000000000001
 0000000000000001 0000000000000001 ffffffff810b9bd0 ffff8801d89cfd40
 ffffffff81ebfe87 0000000000000001 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 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.9.118-g47b77b8 #20
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffffffff84629800 task.stack: ffffffff84600000
RIP: 0010:[<ffffffff81237174>] 
c [<ffffffff81237174>] lookup_chain_cache kernel/locking/lockdep.c:2139 [inline]
RIP: 0010:[<ffffffff81237174>] 
c [<ffffffff81237174>] validate_chain kernel/locking/lockdep.c:2236 [inline]
RIP: 0010:[<ffffffff81237174>] 
c [<ffffffff81237174>] __lock_acquire+0xfe4/0x4070 kernel/locking/lockdep.c:3345
RSP: 0018:ffff8801db2079c0  EFLAGS: 00000893
RAX: 1ffffffff09ee8bf RBX: ffffffff8462a0f0 RCX: 000000008a3ff4fd
RDX: 1ffffffff09f109d RSI: ffffffff8462a0f0 RDI: ffffffff84f745f8
RBP: ffff8801db207b70 R08: ffffffff8462a110 R09: 0000000000000000
R10: ffffffff84629800 R11: 1ffffffff08c541d R12: ffffffff84f745e8
R13: dffffc0000000000 R14: 0000000000000000 R15: 560570adf17204e1
FS:  0000000000000000(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000001790b10 CR3: 00000001ca6c3000 CR4: 00000000001606f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600
Stack:
 ffff8801db207ce8
c ffff8801d9913ea0
c 0000000041b58ab3
c ffffffff843bdcc7
c
 ffffffff811fe080
c ffffffff84629800
c 0000000000000d37
c 000000000000079a
c
 000000000000079a
c 00000000000000a2
c ffffffff8558c600
c 000000000000024d
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
 [<ffffffff8120346a>] load_balance+0x6ea/0x2fa0 kernel/sched/fair.c:9505
 [<ffffffff8120820e>] rebalance_domains+0x6be/0xbc0 kernel/sched/fair.c:10115
 [<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
 [<ffffffff839e897c>] rest_init+0x183/0x189 init/main.c:409
 [<ffffffff84c97943>] start_kernel+0x67e/0x6b2 init/main.c:664
 [<ffffffff84c9629a>] x86_64_start_reservations+0x29/0x2b arch/x86/kernel/head64.c:196
 [<ffffffff84c963db>] x86_64_start_kernel+0x13f/0x162 arch/x86/kernel/head64.c:177
Code: 
ce4 
c74 
c46 
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cfc 
c08 
c74 
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c49 
c8d 
c7c 
c24 
c10 
c48 
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c48 
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c03 
c42 
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c3c 
c28 
c00 
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c22 
c00 
c00 
c4d 
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c7c 
c24 
c10 
c0f 
c84 
ca2 
cf8 
cff 
cff 
c<4c> 
c89 
ce0 
c48 
cc1 
ce8 
c03 
c42 
c80 
c3c 
c28 
c00 
c0f 
c85 
c22 
c22 
c00 
c00 
c4d 
c8b 
c24 
c