[v6.6] INFO: task hung in addrconf_dad_work

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 1e89a1be4fe9 Linux 6.6.117
git tree: linux-6.6.y
console output: https://syzkaller.appspot.com/x/log.txt?x=1070d612580000
kernel config: https://syzkaller.appspot.com/x/.config?x=12606d4b8832c7e4
dashboard link: https://syzkaller.appspot.com/bug?extid=4bfb583ae9cc4f93097e
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=16c7257c580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/ad3647e47b66/disk-1e89a1be.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/d6f7ba94aea7/vmlinux-1e89a1be.xz
kernel image: https://storage.googleapis.com/syzbot-assets/e08af2290355/bzImage-1e89a1be.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+4bfb58...@syzkaller.appspotmail.com

INFO: task kworker/u4:2:42 blocked for more than 141 seconds.
Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/u4:2 state:D stack:24400 pid:42 ppid:2 flags:0x00004000
Workqueue: ipv6_addrconf addrconf_dad_work
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5380 [inline]
__schedule+0x14d2/0x44d0 kernel/sched/core.c:6699
schedule+0xbd/0x170 kernel/sched/core.c:6773
schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:6832
__mutex_lock_common kernel/locking/mutex.c:679 [inline]
__mutex_lock+0x6b7/0xcc0 kernel/locking/mutex.c:747
addrconf_dad_work+0xd0/0x14e0 net/ipv6/addrconf.c:4158
process_one_work kernel/workqueue.c:2634 [inline]
process_scheduled_works+0xa45/0x15b0 kernel/workqueue.c:2711
worker_thread+0xa55/0xfc0 kernel/workqueue.c:2792
kthread+0x2fa/0x390 kernel/kthread.c:388
ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
</TASK>
INFO: task syz-executor:5925 blocked for more than 151 seconds.
Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor state:D stack:21192 pid:5925 ppid:1 flags:0x00004004
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5380 [inline]
__schedule+0x14d2/0x44d0 kernel/sched/core.c:6699
schedule+0xbd/0x170 kernel/sched/core.c:6773
schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:6832
__mutex_lock_common kernel/locking/mutex.c:679 [inline]
__mutex_lock+0x6b7/0xcc0 kernel/locking/mutex.c:747
rtnl_lock net/core/rtnetlink.c:78 [inline]
rtnetlink_rcv_msg+0x76f/0xf10 net/core/rtnetlink.c:6469
netlink_rcv_skb+0x216/0x480 net/netlink/af_netlink.c:2545
netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline]
netlink_unicast+0x751/0x8d0 net/netlink/af_netlink.c:1346
netlink_sendmsg+0x8c1/0xbe0 net/netlink/af_netlink.c:1894
sock_sendmsg_nosec net/socket.c:730 [inline]
__sock_sendmsg net/socket.c:745 [inline]
__sys_sendto+0x46a/0x620 net/socket.c:2201


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