------------[ cut here ]------------
WARNING: kernel/nstree.c:115 at __ns_tree_remove+0x28d/0x330 kernel/nstree.c:115, CPU#1: syz.3.2066/16712
Modules linked in:
CPU: 1 UID: 0 PID: 16712 Comm: syz.3.2066 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
RIP: 0010:__ns_tree_remove+0x28d/0x330 kernel/nstree.c:115
Code: 0f 85 a4 00 00 00 48 8b 04 24 ff 00 48 8b 7c 24 18 48 83 c4 30 5b 41 5c 41 5d 41 5e 41 5f 5d e9 79 62 f8 09 e8 94 f1 31 00 90 <0f> 0b 90 e9 cc fd ff ff e8 86 f1 31 00 90 0f 0b 90 e9 ee fd ff ff
RSP: 0018:ffffc9000386faa8 EFLAGS: 00010283
RAX: ffffffff818de3fc RBX: ffff88802886dc20 RCX: 0000000000080000
RDX: ffffc9000bf0a000 RSI: 0000000000002bf3 RDI: 0000000000002bf4
RBP: dffffc0000000000 R08: ffffffff8e1eff53 R09: 1ffffffff1c3dfea
R10: dffffc0000000000 R11: fffffbfff1c3dfeb R12: ffff88802886dc20
R13: 1ffff1100510db83 R14: ffff88802886dc00 R15: ffffffff8e1ea7c0
FS:  00007f03c07f36c0(0000) GS:ffff888125ae1000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: fffffffffffffffd CR3: 00000000648e0000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 mnt_ns_tree_remove fs/namespace.c:165 [inline]
 free_mnt_ns+0xd1/0x110 fs/namespace.c:4068
 namespace_unlock+0x529/0x760 fs/namespace.c:1710
 class_namespace_excl_destructor fs/namespace.c:96 [inline]
 copy_mnt_ns+0x6e0/0x870 fs/namespace.c:4174
 create_new_namespaces+0xd1/0x720 kernel/nsproxy.c:78
 unshare_nsproxy_namespaces+0x11c/0x170 kernel/nsproxy.c:218
 ksys_unshare+0x4c8/0x8c0 kernel/fork.c:3144
 __do_sys_unshare kernel/fork.c:3215 [inline]
 __se_sys_unshare kernel/fork.c:3213 [inline]
 __x64_sys_unshare+0x38/0x50 kernel/fork.c:3213
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f03bf98eba9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f03c07f3038 EFLAGS: 00000246 ORIG_RAX: 0000000000000110
RAX: ffffffffffffffda RBX: 00007f03bfbd6180 RCX: 00007f03bf98eba9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 000000002c020400
RBP: 00007f03bfa11e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f03bfbd6218 R14: 00007f03bfbd6180 R15: 00007ffd76cb9ce8
 </TASK>