[syzbot ci] Re: ipvlan: support mac-nat mode

[syzbot ci <syzbot+cia97091be86436383@syzkaller.appspotmail.com>]

syzbot ci has tested the following series

[v3] ipvlan: support mac-nat mode
https://lore.kernel.org/all/20251105161450.1730216-1-skorodumov.dmitry@huawei.com
* [PATCH net-next 01/14] ipvlan: Preparation to support mac-nat
* [PATCH net-next 02/14] ipvlan: Send mcasts out directly in ipvlan_xmit_mode_l2()
* [PATCH net-next 03/14] ipvlan: Handle rx mcast-ip and unicast eth
* [PATCH net-next 04/14] ipvlan: Added some kind of MAC NAT
* [PATCH net-next 05/14] ipvlan: Forget all IP when device goes down
* [PATCH net-next 06/14] ipvlan: Support GSO for port -> ipvlan
* [PATCH net-next 07/14] ipvlan: Support IPv6 for learnable l2-bridge
* [PATCH net-next 08/14] ipvlan: Make the addrs_lock be per port
* [PATCH net-next 09/14] ipvlan: Take addr_lock in ipvlan_open()
* [PATCH net-next 10/14] ipvlan: Don't allow children to use IPs of main
* [PATCH net-next 11/14] ipvlan: const-specifier for functions that use iaddr
* [PATCH net-next 12/14] ipvlan: Common code from v6/v4 validator_event
* [PATCH net-next 13/14] ipvlan: common code to handle ipv6/ipv4 address events
* [PATCH net-next 14/14] ipvlan: Ignore PACKET_LOOPBACK in handle_mode_l2()

and found the following issue:
WARNING: suspicious RCU usage in ipvlan_init

Full report is available here:
https://ci.syzbot.org/series/349ca33e-4ae2-4720-9a69-17a2a9e17107

***

WARNING: suspicious RCU usage in ipvlan_init

tree:      net-next
URL:       https://kernel.googlesource.com/pub/scm/linux/kernel/git/netdev/net-next.git
base:      01cc760632b875c4ad0d8fec0b0c01896b8a36d4
arch:      amd64
compiler:  Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
config:    https://ci.syzbot.org/builds/d6598a0d-2fcb-499d-95fc-30c5096555dc/config

batman_adv: batadv0: Not using interface batadv_slave_1 (retrying later): interface not active
hsr_slave_0: entered promiscuous mode
hsr_slave_1: entered promiscuous mode
=============================
WARNING: suspicious RCU usage
syzkaller #0 Not tainted
-----------------------------
./include/linux/inetdevice.h:239 suspicious rcu_dereference_check() usage!

other info that might help us debug this:


rcu_scheduler_active = 2, debug_locks = 1
2 locks held by syz-executor/6496:
 #0: ffffffff8ea2f980 (&ops->srcu#2){.+.+}-{0:0}, at: rtnl_link_ops_get+0x23/0x250
 #1: ffffffff8f2cb3c8 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_newlink+0x8e9/0x1c80

stack backtrace:
CPU: 1 UID: 0 PID: 6496 Comm: syz-executor Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250
 lockdep_rcu_suspicious+0x140/0x1d0
 ipvlan_init+0xff2/0x1260
 register_netdevice+0x6bf/0x1ae0
 ipvlan_link_new+0x57a/0xc70
 rtnl_newlink_create+0x310/0xb00
 rtnl_newlink+0x16e4/0x1c80
 rtnetlink_rcv_msg+0x7cf/0xb70
 netlink_rcv_skb+0x208/0x470
 netlink_unicast+0x82f/0x9e0
 netlink_sendmsg+0x805/0xb30
 __sock_sendmsg+0x21c/0x270
 __sys_sendto+0x3bd/0x520
 __x64_sys_sendto+0xde/0x100
 do_syscall_64+0xfa/0xfa0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f114c590e03
Code: 64 89 02 48 c7 c0 ff ff ff ff eb b7 66 2e 0f 1f 84 00 00 00 00 00 90 80 3d 61 77 22 00 00 41 89 ca 74 14 b8 2c 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 75 c3 0f 1f 40 00 55 48 83 ec 30 44 89 4c 24
RSP: 002b:00007ffecaf08958 EFLAGS: 00000202 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 00007f114d314620 RCX: 00007f114c590e03
RDX: 0000000000000058 RSI: 00007f114d314670 RDI: 0000000000000003
RBP: 0000000000000001 R08: 00007ffecaf08974 R09: 000000000000000c
R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000003
R13: 0000000000000000 R14: 00007f114d314670 R15: 0000000000000000
 </TASK>

=============================
WARNING: suspicious RCU usage
syzkaller #0 Not tainted
-----------------------------
drivers/net/ipvlan/ipvlan_main.c:238 suspicious rcu_dereference_check() usage!

other info that might help us debug this:


rcu_scheduler_active = 2, debug_locks = 1
2 locks held by syz-executor/6496:
 #0: ffffffff8ea2f980 (&ops->srcu#2){.+.+}-{0:0}, at: rtnl_link_ops_get+0x23/0x250
 #1: ffffffff8f2cb3c8 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_newlink+0x8e9/0x1c80

stack backtrace:
CPU: 0 UID: 0 PID: 6496 Comm: syz-executor Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250
 lockdep_rcu_suspicious+0x140/0x1d0
 ipvlan_init+0x1025/0x1260
 register_netdevice+0x6bf/0x1ae0
 ipvlan_link_new+0x57a/0xc70
 rtnl_newlink_create+0x310/0xb00
 rtnl_newlink+0x16e4/0x1c80
 rtnetlink_rcv_msg+0x7cf/0xb70
 netlink_rcv_skb+0x208/0x470
 netlink_unicast+0x82f/0x9e0
 netlink_sendmsg+0x805/0xb30
 __sock_sendmsg+0x21c/0x270
 __sys_sendto+0x3bd/0x520
 __x64_sys_sendto+0xde/0x100
 do_syscall_64+0xfa/0xfa0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f114c590e03
Code: 64 89 02 48 c7 c0 ff ff ff ff eb b7 66 2e 0f 1f 84 00 00 00 00 00 90 80 3d 61 77 22 00 00 41 89 ca 74 14 b8 2c 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 75 c3 0f 1f 40 00 55 48 83 ec 30 44 89 4c 24
RSP: 002b:00007ffecaf08958 EFLAGS: 00000202 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 00007f114d314620 RCX: 00007f114c590e03
RDX: 0000000000000058 RSI: 00007f114d314670 RDI: 0000000000000003
RBP: 0000000000000001 R08: 00007ffecaf08974 R09: 000000000000000c
R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000003
R13: 0000000000000000 R14: 00007f114d314670 R15: 0000000000000000
 </TASK>


***

If these findings have caused you to resend the series or submit a
separate fix, please add the following tag to your commit message:
  Tested-by: syzbot@syzkaller.appspotmail.com

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