INFO: task syz-executor.1:9820 blocked for more than 140 seconds.
      Not tainted 4.9.187+ #17
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.1  D29800  9820  22944 0x00000004
 0000000000000083 ffff8801a3ef0000 ffff880192aed280 ffff8801db721000
 ffff8801d6d3df00 ffff8801db721018 ffff88019ee3fb10 ffffffff8281717e
 ffff8801a3ef0000 ffff8801a3ef0000 00ff88019ee3fa60 ffff8801db7218f0
Call Trace:
 [<00000000030798de>] schedule+0x92/0x1c0 kernel/sched/core.c:3546
 [<00000000d93e2174>] __rwsem_down_write_failed_common kernel/locking/rwsem-xadd.c:549 [inline]
 [<00000000d93e2174>] rwsem_down_write_failed+0x3a3/0x750 kernel/locking/rwsem-xadd.c:578
 [<00000000be8a56de>] call_rwsem_down_write_failed+0x17/0x30 arch/x86/lib/rwsem.S:105
 [<00000000e6a02c01>] __down_write arch/x86/include/asm/rwsem.h:125 [inline]
 [<00000000e6a02c01>] down_write+0x5c/0xa0 kernel/locking/rwsem.c:54
 [<000000006c6ff948>] inode_lock include/linux/fs.h:771 [inline]
 [<000000006c6ff948>] lock_mount+0x8c/0x2c0 fs/namespace.c:2113
 [<00000000234d4f16>] SYSC_pivot_root fs/namespace.c:3172 [inline]
 [<00000000234d4f16>] SyS_pivot_root+0x2a6/0xea0 fs/namespace.c:3148
 [<000000000291cd68>] do_syscall_64+0x1ad/0x5c0 arch/x86/entry/common.c:288
 [<0000000000db2bfd>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb

Showing all locks held in the system:
2 locks held by khungtaskd/24:
 #0:  (rcu_read_lock){......}, at: [<000000002ee6718e>] check_hung_uninterruptible_tasks kernel/hung_task.c:169 [inline]
 #0:  (rcu_read_lock){......}, at: [<000000002ee6718e>] watchdog+0x14b/0xaf0 kernel/hung_task.c:263
 #1:  (tasklist_lock){.+.+..}, at: [<00000000326aa2b5>] debug_show_all_locks+0x7f/0x21f kernel/locking/lockdep.c:4336
2 locks held by getty/2031:
 #0:  (&tty->ldisc_sem){++++++}, at: [<00000000d76a5f46>] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:377
 #1:  (&ldata->atomic_read_lock){+.+...}, at: [<0000000014e38b04>] n_tty_read+0x1fe/0x1820 drivers/tty/n_tty.c:2156
1 lock held by syz-executor.1/9820:
 #0:  (&type->i_mutex_dir_key#7){++++++}, at: [<000000006c6ff948>] inode_lock include/linux/fs.h:771 [inline]
 #0:  (&type->i_mutex_dir_key#7){++++++}, at: [<000000006c6ff948>] lock_mount+0x8c/0x2c0 fs/namespace.c:2113

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

NMI backtrace for cpu 0
CPU: 0 PID: 24 Comm: khungtaskd Not tainted 4.9.187+ #17
 ffff8801d98d7cc8 ffffffff81b64701 0000000000000000 0000000000000000
 0000000000000000 ffffffff81099a01 dffffc0000000000 ffff8801d98d7d00
 ffffffff81b6f99c 0000000000000000 0000000000000000 0000000000000000
Call Trace:
 [<00000000b8c7433e>] __dump_stack lib/dump_stack.c:15 [inline]
 [<00000000b8c7433e>] dump_stack+0xc1/0x120 lib/dump_stack.c:51
 [<00000000095fdf0b>] nmi_cpu_backtrace.cold+0x47/0x87 lib/nmi_backtrace.c:99
 [<00000000e4fecec1>] nmi_trigger_cpumask_backtrace+0x124/0x155 lib/nmi_backtrace.c:60
 [<00000000710bb146>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37
 [<00000000c9f29842>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline]
 [<00000000c9f29842>] check_hung_task kernel/hung_task.c:126 [inline]
 [<00000000c9f29842>] check_hung_uninterruptible_tasks kernel/hung_task.c:183 [inline]
 [<00000000c9f29842>] watchdog+0x670/0xaf0 kernel/hung_task.c:263
 [<000000003e84b961>] kthread+0x278/0x310 kernel/kthread.c:211
 [<0000000062321513>] ret_from_fork+0x5c/0x70 arch/x86/entry/entry_64.S:375
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 9793 Comm: syz-executor.1 Not tainted 4.9.187+ #17
task: 00000000c7d1652b task.stack: 00000000860eade8
RIP: 0010:[<ffffffff812075e2>] 
c [<00000000f3e50127>] __lock_is_held+0xd2/0x130 kernel/locking/lockdep.c:3594
RSP: 0018:ffff8801926df388  EFLAGS: 00000002
RAX: 0000000000000003 RBX: 0000000000000002 RCX: ffff8801a1ef3830
RDX: 0000000000000000 RSI: 00000000000001dd RDI: ffff8801a1ef387a
RBP: ffff8801926df3b8 R08: 0000000000000286 R09: ffff8801a1ef3878
R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801a1ef3858
R13: ffffffff830d57e0 R14: dffffc0000000000 R15: ffff8801a1ef2f80
FS:  00007f14cb193700(0000) GS:ffff8801db700000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f1c10d00f80 CR3: 000000010c359000 CR4: 00000000001606b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Stack:
 ffff8801926df398
c 0000000000000246
c ffffffff830d57e0
c ffff8801a1ef2f80
c
 0000000000000000
c ffff8801a02c3c30
c ffff8801926df3e0
c ffffffff812076f2
c
 0000000000000000
c ffffffff82aff380
c 00000000000001dd
c ffff8801926df418
c
Call Trace:
 [<00000000ecd46153>] lock_is_held+0xb2/0x140 kernel/locking/lockdep.c:3794
 [<000000002f1a47eb>] ___might_sleep+0x1ca/0x280 kernel/sched/core.c:7970
 [<00000000003f3f7c>] __might_sleep+0x95/0x1a0 kernel/sched/core.c:7961
 [<000000008ec750fc>] request_wait_answer+0x141/0x820 fs/fuse/dev.c:477
 [<0000000014327c7c>] __fuse_request_send+0x109/0x1b0 fs/fuse/dev.c:498
 [<0000000079600fb6>] fuse_request_send+0x63/0x70 fs/fuse/dev.c:511
 [<000000005d7a3e7c>] fuse_simple_request+0x2c4/0x660 fs/fuse/dev.c:569
 [<00000000d27be445>] fuse_lookup_name+0x260/0x640 fs/fuse/dir.c:369
 [<00000000de57d15f>] fuse_lookup+0xec/0x3b0 fs/fuse/dir.c:407
 [<000000006d083613>] lookup_slow+0x24b/0x480 fs/namei.c:1709
 [<00000000c1ef9dfe>] walk_component+0x71e/0xce0 fs/namei.c:1825
 [<00000000ae20a0f4>] lookup_last fs/namei.c:2307 [inline]
 [<00000000ae20a0f4>] path_lookupat.isra.0+0x18f/0x3f0 fs/namei.c:2324
 [<00000000bc773466>] filename_lookup+0x1a1/0x3b0 fs/namei.c:2358
 [<000000001190574b>] user_path_at_empty+0x43/0x50 fs/namei.c:2619
 [<00000000a70fff4c>] user_path_at include/linux/namei.h:55 [inline]
 [<00000000a70fff4c>] vfs_fstatat+0xc6/0x170 fs/stat.c:106
 [<00000000ae24c5dd>] vfs_stat fs/stat.c:123 [inline]
 [<00000000ae24c5dd>] SYSC_newstat fs/stat.c:270 [inline]
 [<00000000ae24c5dd>] SyS_newstat+0x94/0x100 fs/stat.c:266
 [<000000000291cd68>] do_syscall_64+0x1ad/0x5c0 arch/x86/entry/common.c:288
 [<0000000000db2bfd>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb
Code: 
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