[syzbot] [netfilter?] WARNING in nf_conntrack_cleanup_net_list (2)

[syzbot <syzbot+122256c3e2bf6ec9f928@syzkaller.appspotmail.com>]

Hello,

syzbot found the following issue on:

HEAD commit:    d60ec36cab33 Merge tag 'mm-hotfixes-stable-2026-05-25-16-2..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=17f1712e580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=e327ee9a867dd6b9
dashboard link: https://syzkaller.appspot.com/bug?extid=122256c3e2bf6ec9f928
compiler:       gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-d60ec36c.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/f8c1a87b3686/vmlinux-d60ec36c.xz
kernel image: https://storage.googleapis.com/syzbot-assets/731575988634/bzImage-d60ec36c.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+122256c3e2bf6ec9f928@syzkaller.appspotmail.com

------------[ cut here ]------------
conntrack cleanup blocked for 60s
WARNING: net/netfilter/nf_conntrack_core.c:2506 at nf_conntrack_cleanup_net_list+0x4f7/0x690 net/netfilter/nf_conntrack_core.c:2506, CPU#2: kworker/u32:12/10858
Modules linked in:
CPU: 2 UID: 0 PID: 10858 Comm: kworker/u32:12 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
Workqueue: netns cleanup_net
RIP: 0010:nf_conntrack_cleanup_net_list+0x4f7/0x690 net/netfilter/nf_conntrack_core.c:2506
Code: 29 c3 48 89 de e8 a9 84 58 f8 48 85 db 78 0f e8 bf 89 58 f8 e8 ea 64 dc 01 e9 0e fc ff ff e8 b0 89 58 f8 48 8d 3d 39 7f 36 07 <67> 48 0f b9 3a eb de 4c 8b 6c 24 40 e8 98 89 58 f8 48 b8 00 00 00
RSP: 0018:ffffc90004057968 EFLAGS: 00010293
RAX: 0000000000000000 RBX: ffffffffffffffff RCX: ffffffff89b02597
RDX: ffff888042c5ca00 RSI: ffffffff89b025b0 RDI: ffffffff90e6a4f0
RBP: 0000000000000001 R08: 0000000000000007 R09: 0000000000000000
R10: ffffffffffffffff R11: 0000000000000000 R12: 0000000000000001
R13: 0000000000000001 R14: ffffc90004057b20 R15: dffffc0000000000
FS:  0000000000000000(0000) GS:ffff8880d656a000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000110c360d0b CR3: 000000004064f000 CR4: 0000000000352ef0
DR0: 0000000000000009 DR1: 00000000000000c9 DR2: 00000000000000f3
DR3: 00000000000000c0 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 ops_exit_list net/core/net_namespace.c:205 [inline]
 ops_undo_list+0x363/0xab0 net/core/net_namespace.c:252
 cleanup_net+0x499/0x920 net/core/net_namespace.c:702
 process_one_work+0xa0e/0x1980 kernel/workqueue.c:3314
 process_scheduled_works kernel/workqueue.c:3397 [inline]
 worker_thread+0x5ef/0xe50 kernel/workqueue.c:3478
 kthread+0x370/0x450 kernel/kthread.c:436
 ret_from_fork+0x72b/0xd50 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
----------------
Code disassembly (best guess):
   0:	29 c3                	sub    %eax,%ebx
   2:	48 89 de             	mov    %rbx,%rsi
   5:	e8 a9 84 58 f8       	call   0xf85884b3
   a:	48 85 db             	test   %rbx,%rbx
   d:	78 0f                	js     0x1e
   f:	e8 bf 89 58 f8       	call   0xf85889d3
  14:	e8 ea 64 dc 01       	call   0x1dc6503
  19:	e9 0e fc ff ff       	jmp    0xfffffc2c
  1e:	e8 b0 89 58 f8       	call   0xf85889d3
  23:	48 8d 3d 39 7f 36 07 	lea    0x7367f39(%rip),%rdi        # 0x7367f63
* 2a:	67 48 0f b9 3a       	ud1    (%edx),%rdi <-- trapping instruction
  2f:	eb de                	jmp    0xf
  31:	4c 8b 6c 24 40       	mov    0x40(%rsp),%r13
  36:	e8 98 89 58 f8       	call   0xf85889d3
  3b:	48                   	rex.W
  3c:	b8                   	.byte 0xb8
  3d:	00 00                	add    %al,(%rax)


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