------------[ cut here ]------------
ida_free called for id=3252 which is not allocated.
WARNING: CPU: 1 PID: 2420 at lib/idr.c:592 ida_free+0x280/0x310 lib/idr.c:592
Modules linked in:
CPU: 1 UID: 0 PID: 2420 Comm: kworker/u8:56 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
Workqueue: netns cleanup_net
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 81 2c 0c 00 90 48 c7 c7 20 27 74 8c 44 89 fe e8 91 1c 59 f6 90 <0f> 0b 90 90 eb 34 e8 75 ae 95 f6 49 bd 00 00 00 00 00 fc ff df eb
RSP: 0018:ffffc900030e73a0 EFLAGS: 00010246
RAX: 3510e15757fa2f00 RBX: 0000000000000a06 RCX: ffff88804f561e40
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000002
RBP: ffffc900030e7498 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffffbfff1b7a118 R12: 1ffff9200061ce78
R13: dffffc0000000000 R14: ffff888033443900 R15: 0000000000000cb4
FS:  0000000000000000(0000) GS:ffff88812649b000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000110c36de4c CR3: 00000000425f0000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 proc_free_inum fs/proc/generic.c:216 [inline]
 pde_put+0x7e/0x1b0 fs/proc/generic.c:696
 remove_proc_subtree+0x3e8/0x530 fs/proc/generic.c:796
 snmp6_unregister_dev+0xae/0xf0 net/ipv6/proc.c:283
 addrconf_ifdown+0x240/0x1880 net/ipv6/addrconf.c:3870
 addrconf_notify+0x1bc/0x1010 net/ipv6/addrconf.c:-1
 notifier_call_chain+0x1b6/0x3e0 kernel/notifier.c:85
 call_netdevice_notifiers_extack net/core/dev.c:2267 [inline]
 call_netdevice_notifiers net/core/dev.c:2281 [inline]
 unregister_netdevice_many_notify+0x14d7/0x1ff0 net/core/dev.c:12254
 ops_exit_rtnl_list net/core/net_namespace.c:187 [inline]
 ops_undo_list+0x3dc/0x990 net/core/net_namespace.c:248
 cleanup_net+0x4d8/0x820 net/core/net_namespace.c:695
 process_one_work kernel/workqueue.c:3263 [inline]
 process_scheduled_works+0xade/0x17b0 kernel/workqueue.c:3346
 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3427
 kthread+0x711/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x436/0x7d0 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>