[v6.6] possible deadlock in team_device_event

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: f34f16e5c632 Linux 6.6.109
git tree: linux-6.6.y
console output: https://syzkaller.appspot.com/x/log.txt?x=1720585b980000
kernel config: https://syzkaller.appspot.com/x/.config?x=12606d4b8832c7e4
dashboard link: https://syzkaller.appspot.com/bug?extid=4b93c981a8b75227635d
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/1d84cf343aca/disk-f34f16e5.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/613ae177a403/vmlinux-f34f16e5.xz
kernel image: https://storage.googleapis.com/syzbot-assets/6b9016970cbc/bzImage-f34f16e5.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+4b93c9...@syzkaller.appspotmail.com

============================================
WARNING: possible recursive locking detected
syzkaller #0 Not tainted
--------------------------------------------
syz.1.3805/21219 is trying to acquire lock:
ffff88804e5ecd00 (team->team_lock_key#11){+.+.}-{3:3}, at: team_port_change_check drivers/net/team/team.c:3007 [inline]
ffff88804e5ecd00 (team->team_lock_key#11){+.+.}-{3:3}, at: team_device_event+0x18a/0xa20 drivers/net/team/team.c:3033

but task is already holding lock:
ffff88804e5ecd00 (team->team_lock_key#11){+.+.}-{3:3}, at: team_del_slave+0x32/0x1c0 drivers/net/team/team.c:1997

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

CPU0
----
lock(team->team_lock_key#11);
lock(team->team_lock_key#11);

*** DEADLOCK ***

May be due to missing lock nesting notation

2 locks held by syz.1.3805/21219:
#0: ffffffff8dfbb4c8 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:78 [inline]
#0: ffffffff8dfbb4c8 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x76f/0xf10 net/core/rtnetlink.c:6472
#1: ffff88804e5ecd00 (team->team_lock_key#11){+.+.}-{3:3}, at: team_del_slave+0x32/0x1c0 drivers/net/team/team.c:1997

stack backtrace:
CPU: 1 PID: 21219 Comm: syz.1.3805 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
Call Trace:
<TASK>
dump_stack_lvl+0x16c/0x230 lib/dump_stack.c:106
check_deadlock kernel/locking/lockdep.c:3062 [inline]
validate_chain kernel/locking/lockdep.c:3856 [inline]
__lock_acquire+0x5d40/0x7c80 kernel/locking/lockdep.c:5137
lock_acquire+0x197/0x410 kernel/locking/lockdep.c:5754
__mutex_lock_common kernel/locking/mutex.c:603 [inline]
__mutex_lock+0x129/0xcc0 kernel/locking/mutex.c:747
team_port_change_check drivers/net/team/team.c:3007 [inline]
team_device_event+0x18a/0xa20 drivers/net/team/team.c:3033
notifier_call_chain+0x197/0x390 kernel/notifier.c:93
call_netdevice_notifiers_extack net/core/dev.c:2064 [inline]
call_netdevice_notifiers net/core/dev.c:2078 [inline]
dev_close_many+0x297/0x400 net/core/dev.c:1619
vlan_device_event+0x1806/0x1ef0 net/8021q/vlan.c:474
notifier_call_chain+0x197/0x390 kernel/notifier.c:93
call_netdevice_notifiers_extack net/core/dev.c:2064 [inline]
call_netdevice_notifiers net/core/dev.c:2078 [inline]
dev_close_many+0x297/0x400 net/core/dev.c:1619
dev_close+0x150/0x200 net/core/dev.c:1641
team_port_del+0x4c8/0xc50 drivers/net/team/team.c:1366
team_del_slave+0x3d/0x1c0 drivers/net/team/team.c:1998
do_set_master net/core/rtnetlink.c:2692 [inline]
do_setlink+0xe92/0x3fb0 net/core/rtnetlink.c:2912
rtnl_setlink+0x399/0x4b0 net/core/rtnetlink.c:3208
rtnetlink_rcv_msg+0x7c7/0xf10 net/core/rtnetlink.c:6475
netlink_rcv_skb+0x216/0x480 net/netlink/af_netlink.c:2545
netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline]
netlink_unicast+0x751/0x8d0 net/netlink/af_netlink.c:1346
netlink_sendmsg+0x8c1/0xbe0 net/netlink/af_netlink.c:1894
sock_sendmsg_nosec net/socket.c:730 [inline]
__sock_sendmsg net/socket.c:745 [inline]
____sys_sendmsg+0x5bf/0x950 net/socket.c:2595
___sys_sendmsg+0x220/0x290 net/socket.c:2649
__sys_sendmsg net/socket.c:2678 [inline]
__do_sys_sendmsg net/socket.c:2687 [inline]
__se_sys_sendmsg+0x1a5/0x270 net/socket.c:2685
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fe59b98eec9
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:00007fe59c784038 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007fe59bbe5fa0 RCX: 00007fe59b98eec9
RDX: 0000000000000000 RSI: 00002000000000c0 RDI: 000000000000000c
RBP: 00007fe59ba11f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fe59bbe6038 R14: 00007fe59bbe5fa0 R15: 00007fff90c2de28
</TASK>


---
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[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 29e53a5b1c4f Linux 5.15.194
git tree: linux-5.15.y
console output: https://syzkaller.appspot.com/x/log.txt?x=146f6a14580000
kernel config: https://syzkaller.appspot.com/x/.config?x=e1bb6d24ef2164eb
dashboard link: https://syzkaller.appspot.com/bug?extid=efc3c89930c4d56e93dc

compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:

disk image: https://storage.googleapis.com/syzbot-assets/8cd4e3ff852c/disk-29e53a5b.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/21e1f773622c/vmlinux-29e53a5b.xz
kernel image: https://storage.googleapis.com/syzbot-assets/8f418c0a25cc/bzImage-29e53a5b.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:

Reported-by: syzbot+efc3c8...@syzkaller.appspotmail.com

============================================
WARNING: possible recursive locking detected
syzkaller #0 Not tainted
--------------------------------------------

syz.3.529/6301 is trying to acquire lock:
ffff888078600d00 (team->team_lock_key#2){+.+.}-{3:3}, at: team_port_change_check drivers/net/team/team.c:3014 [inline]
ffff888078600d00 (team->team_lock_key#2){+.+.}-{3:3}, at: team_device_event+0x1d2/0x9e0 drivers/net/team/team.c:3040

but task is already holding lock:

ffff888078600d00 (team->team_lock_key#2){+.+.}-{3:3}, at: team_del_slave+0x2e/0x1e0 drivers/net/team/team.c:2004

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

CPU0
----

lock(team->team_lock_key#2);
lock(team->team_lock_key#2);

*** DEADLOCK ***

May be due to missing lock nesting notation

2 locks held by syz.3.529/6301:
#0: ffffffff8d238308 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:72 [inline]
#0: ffffffff8d238308 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x974/0xe60 net/core/rtnetlink.c:5647
#1: ffff888078600d00 (team->team_lock_key#2){+.+.}-{3:3}, at: team_del_slave+0x2e/0x1e0 drivers/net/team/team.c:2004

stack backtrace:
CPU: 1 PID: 6301 Comm: syz.3.529 Not tainted syzkaller #0

Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
Call Trace:
<TASK>

dump_stack_lvl+0x168/0x230 lib/dump_stack.c:106
__lock_acquire+0x1227/0x7c60 kernel/locking/lockdep.c:-1
lock_acquire+0x197/0x3f0 kernel/locking/lockdep.c:5623
__mutex_lock_common+0x1eb/0x2390 kernel/locking/mutex.c:596
__mutex_lock kernel/locking/mutex.c:729 [inline]
mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
team_port_change_check drivers/net/team/team.c:3014 [inline]
team_device_event+0x1d2/0x9e0 drivers/net/team/team.c:3040
notifier_call_chain kernel/notifier.c:83 [inline]
raw_notifier_call_chain+0xcb/0x160 kernel/notifier.c:391
call_netdevice_notifiers_extack net/core/dev.c:2061 [inline]
call_netdevice_notifiers net/core/dev.c:2075 [inline]
dev_close_many+0x28d/0x400 net/core/dev.c:1650
vlan_device_event+0x1244/0x1fa0 net/8021q/vlan.c:475
notifier_call_chain kernel/notifier.c:83 [inline]
raw_notifier_call_chain+0xcb/0x160 kernel/notifier.c:391
call_netdevice_notifiers_extack net/core/dev.c:2061 [inline]
call_netdevice_notifiers net/core/dev.c:2075 [inline]
dev_close_many+0x28d/0x400 net/core/dev.c:1650
dev_close+0x14c/0x200 net/core/dev.c:1672
team_port_del+0x4c9/0xc40 drivers/net/team/team.c:1363
team_del_slave+0x39/0x1e0 drivers/net/team/team.c:2005
do_set_master net/core/rtnetlink.c:2561 [inline]
do_setlink+0xe02/0x3980 net/core/rtnetlink.c:2786
rtnl_setlink+0x35b/0x450 net/core/rtnetlink.c:3061
rtnetlink_rcv_msg+0x9b9/0xe60 net/core/rtnetlink.c:5650
netlink_rcv_skb+0x1e0/0x430 net/netlink/af_netlink.c:2507
netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
netlink_unicast+0x774/0x920 net/netlink/af_netlink.c:1344
netlink_sendmsg+0x8ab/0xbc0 net/netlink/af_netlink.c:1918
sock_sendmsg_nosec net/socket.c:704 [inline]
__sock_sendmsg net/socket.c:716 [inline]
____sys_sendmsg+0x5a2/0x8c0 net/socket.c:2436
___sys_sendmsg+0x1f0/0x260 net/socket.c:2490
__sys_sendmsg net/socket.c:2519 [inline]
__do_sys_sendmsg net/socket.c:2528 [inline]
__se_sys_sendmsg+0x190/0x250 net/socket.c:2526
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7fb25cdcaec9

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:00007fb25b032038 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007fb25d021fa0 RCX: 00007fb25cdcaec9
RDX: 0000000000000000 RSI: 00002000000000c0 RDI: 0000000000000008
RBP: 00007fb25ce4df91 R08: 0000000000000000 R09: 0000000000000000

R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000

R13: 00007fb25d022038 R14: 00007fb25d021fa0 R15: 00007ffdcd00cc98