============================================
WARNING: possible recursive locking detected
syzkaller #0 Not tainted
--------------------------------------------
syz.2.17/5093 is trying to acquire lock:
ffff8881213fcce8 (&dev_instance_lock_key#8){+.+.}-{4:4}, at: netdev_lock include/linux/netdevice.h:2752 [inline]
ffff8881213fcce8 (&dev_instance_lock_key#8){+.+.}-{4:4}, at: netdev_lock_ops include/net/netdev_lock.h:42 [inline]
ffff8881213fcce8 (&dev_instance_lock_key#8){+.+.}-{4:4}, at: netdev_sync_lower_features net/core/dev.c:10542 [inline]
ffff8881213fcce8 (&dev_instance_lock_key#8){+.+.}-{4:4}, at: __netdev_update_features+0x811/0x10b0 net/core/dev.c:10712

but task is already holding lock:
ffff8881213fcce8 (&dev_instance_lock_key#8){+.+.}-{4:4}, at: netdev_lock include/linux/netdevice.h:2752 [inline]
ffff8881213fcce8 (&dev_instance_lock_key#8){+.+.}-{4:4}, at: netdev_lock_ops include/net/netdev_lock.h:42 [inline]
ffff8881213fcce8 (&dev_instance_lock_key#8){+.+.}-{4:4}, at: __dev_ethtool net/ethtool/ioctl.c:3227 [inline]
ffff8881213fcce8 (&dev_instance_lock_key#8){+.+.}-{4:4}, at: dev_ethtool+0x4f9/0x1310 net/ethtool/ioctl.c:3490
and the lock comparison function returns 0:

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

       CPU0
       ----
  lock(&dev_instance_lock_key#8);
  lock(&dev_instance_lock_key#8);

 *** DEADLOCK ***

 May be due to missing lock nesting notation

2 locks held by syz.2.17/5093:
 #0: ffffffff84179bc0 (rtnl_mutex){+.+.}-{4:4}, at: dev_ethtool+0xf0/0x1310 net/ethtool/ioctl.c:3489
 #1: ffff8881213fcce8 (&dev_instance_lock_key#8){+.+.}-{4:4}, at: netdev_lock include/linux/netdevice.h:2752 [inline]
 #1: ffff8881213fcce8 (&dev_instance_lock_key#8){+.+.}-{4:4}, at: netdev_lock_ops include/net/netdev_lock.h:42 [inline]
 #1: ffff8881213fcce8 (&dev_instance_lock_key#8){+.+.}-{4:4}, at: __dev_ethtool net/ethtool/ioctl.c:3227 [inline]
 #1: ffff8881213fcce8 (&dev_instance_lock_key#8){+.+.}-{4:4}, at: dev_ethtool+0x4f9/0x1310 net/ethtool/ioctl.c:3490

stack backtrace:
CPU: 0 UID: 0 PID: 5093 Comm: syz.2.17 Not tainted syzkaller #0 PREEMPT(undef) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x128/0x1c0 lib/dump_stack.c:120
 print_deadlock_bug+0x210/0x220 kernel/locking/lockdep.c:3042
 check_deadlock kernel/locking/lockdep.c:3094 [inline]
 validate_chain kernel/locking/lockdep.c:3896 [inline]
 __lock_acquire+0x1084/0x20e0 kernel/locking/lockdep.c:5235
 lock_acquire+0xe9/0x270 kernel/locking/lockdep.c:5866
 __mutex_lock_common kernel/locking/mutex.c:601 [inline]
 __mutex_lock+0xab/0xb20 kernel/locking/mutex.c:746
 netdev_lock include/linux/netdevice.h:2752 [inline]
 netdev_lock_ops include/net/netdev_lock.h:42 [inline]
 netdev_sync_lower_features net/core/dev.c:10542 [inline]
 __netdev_update_features+0x811/0x10b0 net/core/dev.c:10712
 netdev_update_features+0x29/0xd0 net/core/dev.c:10767
 macsec_notify+0x17c/0x2d0 drivers/net/macsec.c:4505
 notifier_call_chain+0xce/0x200 kernel/notifier.c:85
 call_netdevice_notifiers_info net/core/dev.c:2230 [inline]
 call_netdevice_notifiers_extack net/core/dev.c:2268 [inline]
 call_netdevice_notifiers net/core/dev.c:2282 [inline]
 netdev_features_change+0x86/0xb0 net/core/dev.c:1571
 __dev_ethtool net/ethtool/ioctl.c:3457 [inline]
 dev_ethtool+0x1069/0x1310 net/ethtool/ioctl.c:3490
 dev_ioctl+0x2c6/0x970 net/core/dev_ioctl.c:756
 sock_do_ioctl+0x1ae/0x230 net/socket.c:1204
 sock_ioctl+0x474/0x5f0 net/socket.c:1311
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:906 [inline]
 __se_sys_ioctl+0xb9/0x130 fs/ioctl.c:892
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xa4/0x180 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fd51e21ebe9
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:00007fd51e066038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fd51e456090 RCX: 00007fd51e21ebe9
RDX: 0000200000000080 RSI: 0000000000008946 RDI: 0000000000000006
RBP: 00007fd51e2a1e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fd51e456128 R14: 00007fd51e456090 R15: 00007ffce6094e58
 </TASK>