[v6.1] INFO: rcu detected stall in rtnl_newlink (5)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: fb28aa725e05 Linux 6.1.180
git tree: linux-6.1.y
console output: https://syzkaller.appspot.com/x/log.txt?x=13300cc6580000
kernel config: https://syzkaller.appspot.com/x/.config?x=31dfefc4a14efea3
dashboard link: https://syzkaller.appspot.com/bug?extid=f2689b711221203605d4
compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=11319e32580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=17891db9580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/9a6fe2a54d0f/disk-fb28aa72.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/742b23a1d931/vmlinux-fb28aa72.xz
kernel image: https://storage.googleapis.com/syzbot-assets/b3f257c16d2e/bzImage-fb28aa72.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+f2689b...@syzkaller.appspotmail.com

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P4388/1:b..l
(detected by 1, t=10503 jiffies, g=10565, q=1113 ncpus=2)
task:syz-executor state:R running task stack:21616 pid:4388 ppid:4385 flags:0x00004002
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5246 [inline]
__schedule+0x107f/0x4030 kernel/sched/core.c:6563
preempt_schedule_irq+0xbb/0x160 kernel/sched/core.c:6875
irqentry_exit+0x63/0x70 kernel/entry/common.c:439
asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:691
RIP: 0010:ether_addr_equal include/linux/etherdevice.h:349 [inline]
RIP: 0010:ether_addr_equal_unaligned include/linux/etherdevice.h:402 [inline]
RIP: 0010:batadv_compare_eth net/batman-adv/main.h:267 [inline]
RIP: 0010:batadv_check_known_mac_addr+0x1c0/0x3e0 net/batman-adv/hard-interface.c:521
Code: 8b 44 24 20 42 80 3c 28 00 74 08 4c 89 f7 e8 6f 40 db f7 49 8b 2e 48 89 d8 48 c1 e8 03 42 0f b6 04 28 84 c0 0f 85 fa 00 00 00 <44> 8b 33 48 89 e8 48 c1 e8 03 42 0f b6 04 28 84 c0 0f 85 00 01 00
RSP: 0018:ffffc90003ea6e18 EFLAGS: 00000246
RAX: 0000000000000000 RBX: ffff888027a1b928 RCX: 0000000000000000
RDX: ffff888029df0000 RSI: 0000000000000000 RDI: 0000000000000002
RBP: ffff88805712cc28 R08: ffffc90003ea6aa7 R09: 1ffff920007d4d54
R10: dffffc0000000000 R11: fffff520007d4d55 R12: 0000000000000000
R13: dffffc0000000000 R14: ffff88807c328380 R15: ffff88802973d800
batadv_hard_if_event+0x490/0x1510 net/batman-adv/hard-interface.c:992
notifier_call_chain kernel/notifier.c:87 [inline]
raw_notifier_call_chain+0xcb/0x160 kernel/notifier.c:455
call_netdevice_notifiers_extack net/core/dev.c:2052 [inline]
call_netdevice_notifiers net/core/dev.c:2066 [inline]
dev_set_mac_address+0x2ed/0x400 net/core/dev.c:8937
dev_set_mac_address_user+0x2d/0x50 net/core/dev.c:8951
do_setlink+0x7eb/0x29c0 net/core/rtnetlink.c:2800
__rtnl_newlink net/core/rtnetlink.c:3622 [inline]
rtnl_newlink+0x16e4/0x1f90 net/core/rtnetlink.c:3669
rtnetlink_rcv_msg+0x863/0xfb0 net/core/rtnetlink.c:6166
netlink_rcv_skb+0x1ef/0x440 net/netlink/af_netlink.c:2516
netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
netlink_unicast+0x7ad/0x920 net/netlink/af_netlink.c:1344
netlink_sendmsg+0x8ad/0xbd0 net/netlink/af_netlink.c:1877
sock_sendmsg_nosec net/socket.c:718 [inline]
__sock_sendmsg net/socket.c:730 [inline]
__sys_sendto+0x497/0x650 net/socket.c:2153
__do_sys_sendto net/socket.c:2165 [inline]
__se_sys_sendto net/socket.c:2161 [inline]
__x64_sys_sendto+0xda/0xf0 net/socket.c:2161
do_syscall_x64 arch/x86/entry/common.c:46 [inline]
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f03f3b5e84e
RSP: 002b:00007ffcb4a0f608 EFLAGS: 00000246 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 0000555578480500 RCX: 00007f03f3b5e84e
RDX: 000000000000002c RSI: 00007f03f4954670 RDI: 0000000000000003
RBP: 0000000000000001 R08: 00007ffcb4a0f684 R09: 000000000000000c
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000003
R13: 0000000000000000 R14: 00007f03f4954670 R15: 0000000000000000
</TASK>


---
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 syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.

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