possible deadlock in team_device_event

Status: upstream: reported on 2026/08/01 06:26
Reported-by: syzbot+8939b8184e487aa98371@syzkaller.appspotmail.com
First crash: 2d06h, last: 2d06h
Similar bugs (6)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.6 possible deadlock in team_device_event 4 5 102d 302d 0/2 auto-obsoleted due to no activity on 2026/07/31 14:32
upstream possible deadlock in team_device_event net 4 30 2160d 2228d 0/29 auto-closed as invalid on 2020/12/31 13:59
linux-5.15 possible deadlock in team_device_event (2) 4 2 126d 137d 0/3 auto-obsoleted due to no activity on 2026/07/08 12:05
upstream possible deadlock in team_device_event (3) net 4 syz, C error 38569 344d 815d 29/29 fixed on 2025/09/04 16:57
upstream possible deadlock in team_device_event (2) net 4 8 1708d 1944d 0/29 auto-closed as invalid on 2022/03/29 04:55
linux-5.15 possible deadlock in team_device_event 4 1 293d 293d 0/3 auto-obsoleted due to no activity on 2026/01/21 16:55

Sample crash report:
bond0: (slave syz_tun): Releasing backup interface
bond0: (slave syz_tun): the permanent HWaddr of slave - aa:aa:aa:aa:aa:aa - is still in use by bond - set the HWaddr of slave to a different address to avoid conflicts
============================================
WARNING: possible recursive locking detected
syzkaller #0 Not tainted
--------------------------------------------
syz.1.3659/19319 is trying to acquire lock:
ffff88807aab4d00 (team->team_lock_key#12){+.+.}-{3:3}, at: team_port_change_check drivers/net/team/team.c:3027 [inline]
ffff88807aab4d00 (team->team_lock_key#12){+.+.}-{3:3}, at: team_device_event+0x1d6/0x9c0 drivers/net/team/team.c:3053

but task is already holding lock:
ffff88807aab4d00 (team->team_lock_key#12){+.+.}-{3:3}, at: team_del_slave+0x2d/0x1b0 drivers/net/team/team.c:2016

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

       CPU0
       ----
  lock(team->team_lock_key#12);
  lock(team->team_lock_key#12);

 *** DEADLOCK ***

 May be due to missing lock nesting notation

2 locks held by syz.1.3659/19319:
 #0: ffffffff8dd5b968 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:74 [inline]
 #0: ffffffff8dd5b968 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x80d/0xfb0 net/core/rtnetlink.c:6163
 #1: ffff88807aab4d00 (team->team_lock_key#12){+.+.}-{3:3}, at: team_del_slave+0x2d/0x1b0 drivers/net/team/team.c:2016

stack backtrace:
CPU: 1 PID: 19319 Comm: syz.1.3659 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0x188/0x24e lib/dump_stack.c:106
 __lock_acquire+0x12c8/0x7c40 kernel/locking/lockdep.c:-1
 lock_acquire+0x1bb/0x4a0 kernel/locking/lockdep.c:5676
 __mutex_lock_common kernel/locking/mutex.c:603 [inline]
 __mutex_lock+0x12d/0xae0 kernel/locking/mutex.c:747
 team_port_change_check drivers/net/team/team.c:3027 [inline]
 team_device_event+0x1d6/0x9c0 drivers/net/team/team.c:3053
 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_close_many+0x2a2/0x400 net/core/dev.c:1614
 vlan_device_event+0x12b2/0x1e20 net/8021q/vlan.c:476
 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_close_many+0x2a2/0x400 net/core/dev.c:1614
 dev_close+0x154/0x210 net/core/dev.c:1636
 team_port_del+0x4ce/0xc30 drivers/net/team/team.c:1375
 team_del_slave+0x38/0x1b0 drivers/net/team/team.c:2017
 do_set_master net/core/rtnetlink.c:2628 [inline]
 do_setlink+0xdf1/0x29c0 net/core/rtnetlink.c:2852
 rtnl_group_changelink net/core/rtnetlink.c:3375 [inline]
 __rtnl_newlink net/core/rtnetlink.c:3632 [inline]
 rtnl_newlink+0x10bc/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_sendmsg+0x5ed/0x9a0 net/socket.c:2519
 ___sys_sendmsg+0x2a2/0x360 net/socket.c:2573
 __sys_sendmsg net/socket.c:2602 [inline]
 __do_sys_sendmsg net/socket.c:2611 [inline]
 __se_sys_sendmsg+0x1c3/0x2b0 net/socket.c:2609
 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: 0033:0x7fbf5099e019
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fbf518ce028 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007fbf50c25fa0 RCX: 00007fbf5099e019
RDX: 0000000000000000 RSI: 0000200000000280 RDI: 0000000000000003
RBP: 00007fbf50a3500c R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fbf50c26038 R14: 00007fbf50c25fa0 R15: 00007ffe18e1c4f8
 </TASK>

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/08/01 06:26 linux-6.1.y fb28aa725e05 e611ffe1 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan possible deadlock in team_device_event
* Struck through repros no longer work on HEAD.