[v5.15] INFO: task hung in __netlink_dump_start (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: b9d57c40a767 Linux 5.15.203
git tree: linux-5.15.y
console output: https://syzkaller.appspot.com/x/log.txt?x=11f50836580000
kernel config: https://syzkaller.appspot.com/x/.config?x=353ae28c40b35af5
dashboard link: https://syzkaller.appspot.com/bug?extid=06a499b54796d6bfed75
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/34313629ba4f/disk-b9d57c40.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/402f526e5a98/vmlinux-b9d57c40.xz
kernel image: https://storage.googleapis.com/syzbot-assets/45f7694e9617/bzImage-b9d57c40.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+06a499...@syzkaller.appspotmail.com

INFO: task dhcpcd:3855 blocked for more than 143 seconds.
Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:dhcpcd state:D stack:25744 pid: 3855 ppid: 1 flags:0x00004202
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5049 [inline]
__schedule+0x11ef/0x43c0 kernel/sched/core.c:6395
schedule+0x11b/0x1e0 kernel/sched/core.c:6478
schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:6537
__mutex_lock_common+0xcfc/0x2400 kernel/locking/mutex.c:669
__mutex_lock kernel/locking/mutex.c:729 [inline]
mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
__netlink_dump_start+0x11f/0x700 net/netlink/af_netlink.c:2352
netlink_dump_start include/linux/netlink.h:258 [inline]
rtnetlink_rcv_msg+0xdd9/0xf30 net/core/rtnetlink.c:5643
netlink_rcv_skb+0x1f5/0x440 net/netlink/af_netlink.c:2507
netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
netlink_unicast+0x774/0x920 net/netlink/af_netlink.c:1344
netlink_sendmsg+0x8ba/0xbe0 net/netlink/af_netlink.c:1918
sock_sendmsg_nosec net/socket.c:706 [inline]
__sock_sendmsg net/socket.c:718 [inline]
____sys_sendmsg+0x5b7/0x8f0 net/socket.c:2445
___sys_sendmsg+0x236/0x2e0 net/socket.c:2499
__sys_sendmsg net/socket.c:2528 [inline]
__do_sys_sendmsg net/socket.c:2537 [inline]
__se_sys_sendmsg+0x1af/0x290 net/socket.c:2535
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7faf01f6f407
RSP: 002b:00007fff016ec8d0 EFLAGS: 00000202 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007faf01ee5740 RCX: 00007faf01f6f407
RDX: 0000000000000000 RSI: 00007fff016ec950 RDI: 000000000000000c
RBP: 00007fff016f0b70 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 000055f1f719fc60
R13: 000000000000000c R14: 00007fff016f0b30 R15: 00007fff016f0b70
</TASK>


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