syzbot

============================================
WARNING: possible recursive locking detected
syzkaller #0 Not tainted
--------------------------------------------
syz.1.4406/15156 is trying to acquire lock:
ffff88805721cd30 (&dev_instance_lock_key#20){+.+.}-{4:4}, at: netdev_lock include/linux/netdevice.h:2761 [inline]
ffff88805721cd30 (&dev_instance_lock_key#20){+.+.}-{4:4}, at: netdev_lock_ops include/net/netdev_lock.h:42 [inline]
ffff88805721cd30 (&dev_instance_lock_key#20){+.+.}-{4:4}, at: netdev_lock_ops include/net/netdev_lock.h:39 [inline]
ffff88805721cd30 (&dev_instance_lock_key#20){+.+.}-{4:4}, at: netdev_sync_lower_features net/core/dev.c:10649 [inline]
ffff88805721cd30 (&dev_instance_lock_key#20){+.+.}-{4:4}, at: __netdev_update_features+0x915/0x1da0 net/core/dev.c:10819

but task is already holding lock:
ffff88805721cd30 (&dev_instance_lock_key#20){+.+.}-{4:4}, at: netdev_lock include/linux/netdevice.h:2761 [inline]
ffff88805721cd30 (&dev_instance_lock_key#20){+.+.}-{4:4}, at: netdev_lock_ops include/net/netdev_lock.h:42 [inline]
ffff88805721cd30 (&dev_instance_lock_key#20){+.+.}-{4:4}, at: netdev_lock_ops include/net/netdev_lock.h:39 [inline]
ffff88805721cd30 (&dev_instance_lock_key#20){+.+.}-{4:4}, at: __dev_ethtool net/ethtool/ioctl.c:3235 [inline]
ffff88805721cd30 (&dev_instance_lock_key#20){+.+.}-{4:4}, at: dev_ethtool+0x37b/0x5bc0 net/ethtool/ioctl.c:3502
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#20);
  lock(&dev_instance_lock_key#20);

 *** DEADLOCK ***

 May be due to missing lock nesting notation

2 locks held by syz.1.4406/15156:
 #0: ffffffff90383708 (rtnl_mutex){+.+.}-{4:4}, at: dev_ethtool+0x253/0x5bc0 net/ethtool/ioctl.c:3501
 #1: ffff88805721cd30 (&dev_instance_lock_key#20){+.+.}-{4:4}, at: netdev_lock include/linux/netdevice.h:2761 [inline]
 #1: ffff88805721cd30 (&dev_instance_lock_key#20){+.+.}-{4:4}, at: netdev_lock_ops include/net/netdev_lock.h:42 [inline]
 #1: ffff88805721cd30 (&dev_instance_lock_key#20){+.+.}-{4:4}, at: netdev_lock_ops include/net/netdev_lock.h:39 [inline]
 #1: ffff88805721cd30 (&dev_instance_lock_key#20){+.+.}-{4:4}, at: __dev_ethtool net/ethtool/ioctl.c:3235 [inline]
 #1: ffff88805721cd30 (&dev_instance_lock_key#20){+.+.}-{4:4}, at: dev_ethtool+0x37b/0x5bc0 net/ethtool/ioctl.c:3502

stack backtrace:
CPU: 0 UID: 0 PID: 15156 Comm: syz.1.4406 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
 print_deadlock_bug+0x1e9/0x240 kernel/locking/lockdep.c:3041
 check_deadlock kernel/locking/lockdep.c:3093 [inline]
 validate_chain kernel/locking/lockdep.c:3895 [inline]
 __lock_acquire+0x1133/0x1ce0 kernel/locking/lockdep.c:5237
 lock_acquire kernel/locking/lockdep.c:5868 [inline]
 lock_acquire+0x179/0x350 kernel/locking/lockdep.c:5825
 __mutex_lock_common kernel/locking/mutex.c:598 [inline]
 __mutex_lock+0x193/0x1060 kernel/locking/mutex.c:760
 netdev_lock include/linux/netdevice.h:2761 [inline]
 netdev_lock_ops include/net/netdev_lock.h:42 [inline]
 netdev_lock_ops include/net/netdev_lock.h:39 [inline]
 netdev_sync_lower_features net/core/dev.c:10649 [inline]
 __netdev_update_features+0x915/0x1da0 net/core/dev.c:10819
 netdev_change_features+0x64/0xb0 net/core/dev.c:10893
 team_compute_features drivers/net/team/team_core.c:1039 [inline]
 team_device_event+0x421/0x520 drivers/net/team/team_core.c:2997
 notifier_call_chain+0xbc/0x410 kernel/notifier.c:85
 call_netdevice_notifiers_info+0xbe/0x140 net/core/dev.c:2229
 call_netdevice_notifiers_extack net/core/dev.c:2267 [inline]
 call_netdevice_notifiers net/core/dev.c:2281 [inline]
 netdev_features_change+0x79/0xa0 net/core/dev.c:1570
 __dev_ethtool net/ethtool/ioctl.c:3469 [inline]
 dev_ethtool+0x9b8/0x5bc0 net/ethtool/ioctl.c:3502
 dev_ioctl+0x290/0x10e0 net/core/dev_ioctl.c:759
 sock_do_ioctl+0x19d/0x280 net/socket.c:1252
 sock_ioctl+0x227/0x6b0 net/socket.c:1359
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:598 [inline]
 __se_sys_ioctl fs/ioctl.c:584 [inline]
 __x64_sys_ioctl+0x18b/0x210 fs/ioctl.c:584
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0x4c0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f3670b8ebe9
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:00007f3671a35038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f3670dc5fa0 RCX: 00007f3670b8ebe9
RDX: 0000200000000080 RSI: 0000000000008946 RDI: 0000000000000004
RBP: 00007f3670c11e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f3670dc6038 R14: 00007f3670dc5fa0 R15: 00007ffde4c51d98
 </TASK>