INFO: task syz-executor2:30937 blocked for more than 140 seconds.
      Not tainted 4.9.113-g90e7a90 #16
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor2   D29168 30937   3898 0x00000004
 ffff880198341800 ffff8801b85dea00 ffff8801b85dea00 ffff880198340000
 ffff8801db321c18 ffff880197c77650 ffffffff839ea29d dffffc0000000000
 ffff8801d9c40c10 ffff880197c77610 00ff8801983420c0 ffff8801db3224e8
Call Trace:
 [<ffffffff839eb89f>] schedule+0x7f/0x1b0 kernel/sched/core.c:3553
 [<ffffffff815c7dd2>] d_wait_lookup fs/dcache.c:2455 [inline]
 [<ffffffff815c7dd2>] d_alloc_parallel+0xeb2/0x17c0 fs/dcache.c:2537
 [<ffffffff81594d8c>] lookup_slow+0x19c/0x470 fs/namei.c:1650
 [<ffffffff815a13b6>] walk_component+0x716/0x1bb0 fs/namei.c:1784
 [<ffffffff815a3d16>] lookup_last fs/namei.c:2266 [inline]
 [<ffffffff815a3d16>] path_lookupat.isra.41+0x186/0x410 fs/namei.c:2283
 [<ffffffff815a97c7>] filename_lookup.part.55+0x177/0x370 fs/namei.c:2317
 [<ffffffff815a9b83>] filename_lookup fs/namei.c:2310 [inline]
 [<ffffffff815a9b83>] user_path_at_empty+0x53/0x70 fs/namei.c:2578
 [<ffffffff81580b66>] user_path_at include/linux/namei.h:55 [inline]
 [<ffffffff81580b66>] vfs_fstatat+0xc6/0x170 fs/stat.c:106
 [<ffffffff81581d16>] vfs_stat fs/stat.c:123 [inline]
 [<ffffffff81581d16>] SYSC_newstat+0x86/0xf0 fs/stat.c:270
 [<ffffffff8158211d>] SyS_newstat+0x1d/0x30 fs/stat.c:266
 [<ffffffff81006316>] do_syscall_64+0x1a6/0x490 arch/x86/entry/common.c:282
 [<ffffffff839fb193>] 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: [<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 rs:main Q:Reg/3679:
 #0:  (&f->f_pos_lock){+.+.+.}, at: [<ffffffff815d826c>] __fdget_pos+0xac/0xd0 fs/file.c:781
 #1:  (sb_writers#3){.+.+.+}, at: [<ffffffff81572d4e>] file_start_write include/linux/fs.h:2640 [inline]
 #1:  (sb_writers#3){.+.+.+}, at: [<ffffffff81572d4e>] vfs_write+0x3ae/0x530 fs/read_write.c:556
2 locks held by getty/3777:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff839f9342>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+...}, at: [<ffffffff821200e2>] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2142
1 lock held by syz-executor2/30875:
 #0:  (&sb->s_type->i_mutex_key#26){++++++}, at: [<ffffffff81594d31>] inode_lock_shared include/linux/fs.h:776 [inline]
 #0:  (&sb->s_type->i_mutex_key#26){++++++}, at: [<ffffffff81594d31>] lookup_slow+0x141/0x470 fs/namei.c:1645
1 lock held by syz-executor2/30937:
 #0:  (&sb->s_type->i_mutex_key#26){++++++}, at: [<ffffffff81594d31>] inode_lock_shared include/linux/fs.h:776 [inline]
 #0:  (&sb->s_type->i_mutex_key#26){++++++}, at: [<ffffffff81594d31>] lookup_slow+0x141/0x470 fs/namei.c:1645

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

NMI backtrace for cpu 1
CPU: 1 PID: 519 Comm: khungtaskd Not tainted 4.9.113-g90e7a90 #16
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801d85ffd08 ffffffff81eb4569 0000000000000000 0000000000000001
 0000000000000001 0000000000000001 ffffffff810b9bd0 ffff8801d85ffd40
 ffffffff81ebf867 0000000000000001 0000000000000000 0000000000000003
Call Trace:
 [<ffffffff81eb4569>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81eb4569>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff81ebf867>] nmi_cpu_backtrace.cold.2+0x48/0x87 lib/nmi_backtrace.c:99
 [<ffffffff81ebf7fa>] 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
 [<ffffffff839fb35c>] 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 skipped: idling at pc 0xffffffff839f9da6