[v6.6] INFO: task hung in ip_tunnel_delete_nets

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 924b4a879cbb Linux 6.6.142
git tree: linux-6.6.y
console output: https://syzkaller.appspot.com/x/log.txt?x=1164ba86580000
kernel config: https://syzkaller.appspot.com/x/.config?x=90249d2d52c08134
dashboard link: https://syzkaller.appspot.com/bug?extid=ac95389c06ff9d8eb474
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/9e93d24918c0/disk-924b4a87.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/93a808a8e8a1/vmlinux-924b4a87.xz
kernel image: https://storage.googleapis.com/syzbot-assets/813dba374501/bzImage-924b4a87.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+ac9538...@syzkaller.appspotmail.com

INFO: task kworker/u4:8:3458 blocked for more than 143 seconds.
Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/u4:8 state:D stack:21736 pid:3458 ppid:2 flags:0x00004000
Workqueue: netns cleanup_net
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5381 [inline]
__schedule+0x1553/0x45a0 kernel/sched/core.c:6700
schedule+0xbd/0x170 kernel/sched/core.c:6774
schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:6833
__mutex_lock_common kernel/locking/mutex.c:679 [inline]
__mutex_lock+0x6a9/0xcc0 kernel/locking/mutex.c:747
ip_tunnel_delete_nets+0xd4/0x370 net/ipv4/ip_tunnel.c:1152


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title

If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)

If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report

If you want to undo deduplication, reply with:
#syz undup