------------[ cut here ]------------
mnt_ns_attached(mnt)
WARNING: fs/namespace.c:1081 at mnt_add_to_ns+0x487/0x490, CPU#0: syz.5.103/6750
Modules linked in:
CPU: 0 UID: 0 PID: 6750 Comm: syz.5.103 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
RIP: 0010:mnt_add_to_ns+0x487/0x490
Code: 3c 03 00 74 08 4c 89 f7 e8 c6 2c e3 ff 4d 89 26 48 83 c4 48 5b 41 5c 41 5d 41 5e 41 5f 5d e9 d0 81 64 09 cc e8 fa e1 78 ff 90 <0f> 0b 90 e9 d0 fb ff ff 90 90 90 90 90 90 90 90 90 90 90 90 90 90
RSP: 0018:ffffc90006367c60 EFLAGS: 00010293
RAX: ffffffff824cc6d6 RBX: dffffc0000000000 RCX: ffff888115911d40
RDX: 0000000000000000 RSI: ffff88816b44ee40 RDI: ffff8881bf363e40
RBP: ffffc90006367df0 R08: ffff88816b44ea57 R09: 0000000000000000
R10: ffff88816b44ea48 R11: ffffed102d689d4b R12: ffff88816b44ee40
R13: dffffc0000000000 R14: ffff88816b44ee00 R15: ffff8881bf363e40
FS:  00007f9bfd97d6c0(0000) GS:ffff88818de5f000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f9bfd97cff8 CR3: 0000000025b9c000 CR4: 00000000000006f0
Call Trace:
 <TASK>
 open_new_namespace+0xa9d/0xd90
 vfs_open_tree+0x33a/0x3e0
 __x64_sys_open_tree+0x96/0x110
 do_syscall_64+0x14d/0xf80
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f9bfcb9c799
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f9bfd97d028 EFLAGS: 00000246 ORIG_RAX: 00000000000001ac
RAX: ffffffffffffffda RBX: 00007f9bfce16090 RCX: 00007f9bfcb9c799
RDX: 0000000000001002 RSI: 0000200000000540 RDI: ffffffffffffff9c
RBP: 00007f9bfcc32c99 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f9bfce16128 R14: 00007f9bfce16090 R15: 00007fffc149c9b8
 </TASK>
