netdevsim netdevsim0 netdevsim1: unset [1, 0] type 2 family 0 port 6081 - 0
netdevsim netdevsim0 netdevsim2: unset [1, 0] type 2 family 0 port 6081 - 0
netdevsim netdevsim0 netdevsim3: unset [1, 0] type 2 family 0 port 6081 - 0
============================================
WARNING: possible recursive locking detected
6.14.0-rc5-syzkaller-01140-ge2537326e3b6 #0 Not tainted
--------------------------------------------
syz.0.241/7020 is trying to acquire lock:
ffff88807c2c4d28 (&dev->lock){+.+.}-{4:4}, at: netdev_lock include/linux/netdevice.h:2765 [inline]
ffff88807c2c4d28 (&dev->lock){+.+.}-{4:4}, at: netdev_lock_ops include/linux/netdevice.h:2804 [inline]
ffff88807c2c4d28 (&dev->lock){+.+.}-{4:4}, at: dev_set_allmulti+0x11c/0x270 net/core/dev_api.c:277

but task is already holding lock:
ffff88807c2c4d28 (&dev->lock){+.+.}-{4:4}, at: netdev_lock include/linux/netdevice.h:2765 [inline]
ffff88807c2c4d28 (&dev->lock){+.+.}-{4:4}, at: netdev_lock_ops include/linux/netdevice.h:2804 [inline]
ffff88807c2c4d28 (&dev->lock){+.+.}-{4:4}, at: do_setlink+0x205/0x40f0 net/core/rtnetlink.c:3024

other info that might help us debug this:
 Possible unsafe locking scenario:

       CPU0
       ----
  lock(&dev->lock);
  lock(&dev->lock);

 *** DEADLOCK ***

 May be due to missing lock nesting notation

2 locks held by syz.0.241/7020:
 #0: ffffffff8fed6848 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_lock net/core/rtnetlink.c:79 [inline]
 #0: ffffffff8fed6848 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_nets_lock net/core/rtnetlink.c:340 [inline]
 #0: ffffffff8fed6848 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_newlink+0xc4c/0x1d90 net/core/rtnetlink.c:4053
 #1: ffff88807c2c4d28 (&dev->lock){+.+.}-{4:4}, at: netdev_lock include/linux/netdevice.h:2765 [inline]
 #1: ffff88807c2c4d28 (&dev->lock){+.+.}-{4:4}, at: netdev_lock_ops include/linux/netdevice.h:2804 [inline]
 #1: ffff88807c2c4d28 (&dev->lock){+.+.}-{4:4}, at: do_setlink+0x205/0x40f0 net/core/rtnetlink.c:3024

stack backtrace:
CPU: 1 UID: 0 PID: 7020 Comm: syz.0.241 Not tainted 6.14.0-rc5-syzkaller-01140-ge2537326e3b6 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120
 print_deadlock_bug+0x483/0x620 kernel/locking/lockdep.c:3039
 check_deadlock kernel/locking/lockdep.c:3091 [inline]
 validate_chain+0x15e2/0x5920 kernel/locking/lockdep.c:3893
 __lock_acquire+0x1397/0x2100 kernel/locking/lockdep.c:5228
 lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5851
 __mutex_lock_common kernel/locking/mutex.c:585 [inline]
 __mutex_lock+0x19c/0x1010 kernel/locking/mutex.c:730
 netdev_lock include/linux/netdevice.h:2765 [inline]
 netdev_lock_ops include/linux/netdevice.h:2804 [inline]
 dev_set_allmulti+0x11c/0x270 net/core/dev_api.c:277
 vlan_dev_stop+0xb0/0x330 net/8021q/vlan_dev.c:319
 __dev_close_many+0x3a6/0x700 net/core/dev.c:1716
 dev_close_many+0x24e/0x4c0 net/core/dev.c:1741
 vlan_device_event+0x18b7/0x1de0 net/8021q/vlan.c:450
 notifier_call_chain+0x1a5/0x3f0 kernel/notifier.c:85
 __dev_notify_flags+0x207/0x400
 netif_change_flags+0xf0/0x1a0 net/core/dev.c:9442
 do_setlink+0xf42/0x40f0 net/core/rtnetlink.c:3141
 rtnl_group_changelink net/core/rtnetlink.c:3772 [inline]
 __rtnl_newlink net/core/rtnetlink.c:3926 [inline]
 rtnl_newlink+0x141c/0x1d90 net/core/rtnetlink.c:4054
 rtnetlink_rcv_msg+0x791/0xcf0 net/core/rtnetlink.c:6944
 netlink_rcv_skb+0x206/0x480 net/netlink/af_netlink.c:2534
 netlink_unicast_kernel net/netlink/af_netlink.c:1313 [inline]
 netlink_unicast+0x7f6/0x990 net/netlink/af_netlink.c:1339
 netlink_sendmsg+0x8de/0xcb0 net/netlink/af_netlink.c:1883
 sock_sendmsg_nosec net/socket.c:709 [inline]
 __sock_sendmsg+0x221/0x270 net/socket.c:724
 ____sys_sendmsg+0x53a/0x860 net/socket.c:2564
 ___sys_sendmsg net/socket.c:2618 [inline]
 __sys_sendmsg+0x269/0x350 net/socket.c:2650
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f38a5b8d169
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f38a69ff038 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f38a5da5fa0 RCX: 00007f38a5b8d169
RDX: 0000000000000000 RSI: 0000400000000140 RDI: 0000000000000004
RBP: 00007f38a5c0e2a0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f38a5da5fa0 R15: 00007fffd48f5f98
 </TASK>