------------[ cut here ]------------
ida_free called for id=967 which is not allocated.
WARNING: CPU: 1 PID: 9931 at lib/idr.c:592 ida_free+0x280/0x310 lib/idr.c:592
Modules linked in:
CPU: 1 UID: 0 PID: 9931 Comm: syz.4.1087 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
RIP: 0010:ida_free+0x280/0x310 lib/idr.c:592
Code: 00 00 00 00 fc ff df 48 8b 5c 24 10 48 8b 7c 24 40 48 89 de e8 21 50 0c 00 90 48 c7 c7 40 ce 94 8c 44 89 fe e8 11 30 47 f6 90 <0f> 0b 90 90 eb 34 e8 65 13 84 f6 49 bd 00 00 00 00 00 fc ff df eb
RSP: 0018:ffffc9001cf07b40 EFLAGS: 00010246
RAX: 5689a05395ff9d00 RBX: 0000000000000a02 RCX: ffff888073a38000
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000002
RBP: ffffc9001cf07c40 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffffbfff1bfa138 R12: 1ffff920039e0f6c
R13: dffffc0000000000 R14: ffff8881412a8000 R15: 00000000000003c7
FS:  00007fb9520a06c0(0000) GS:ffff888125e3b000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 0000000030ee2000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 copy_mnt_ns+0x197/0x820 fs/namespace.c:4168
 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:3132
 __do_sys_unshare kernel/fork.c:3203 [inline]
 __se_sys_unshare kernel/fork.c:3201 [inline]
 __x64_sys_unshare+0x38/0x50 kernel/fork.c:3201
 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: 0033:0x7fb95118eec9
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:00007fb9520a0038 EFLAGS: 00000246 ORIG_RAX: 0000000000000110
RAX: ffffffffffffffda RBX: 00007fb9513e6180 RCX: 00007fb95118eec9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 000000002c060000
RBP: 00007fb951211f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fb9513e6218 R14: 00007fb9513e6180 R15: 00007ffc9d8bcf88
 </TASK>