============================================
WARNING: possible recursive locking detected
6.14.0-syzkaller-g0c2623cef4f4 #0 Not tainted
--------------------------------------------
dhcpcd/5505 is trying to acquire lock:
ffff88802db40d30 (&dev->lock){+.+.}-{4:4}, at: netdev_lock include/linux/netdevice.h:2751 [inline]
ffff88802db40d30 (&dev->lock){+.+.}-{4:4}, at: netif_napi_add_weight include/linux/netdevice.h:2783 [inline]
ffff88802db40d30 (&dev->lock){+.+.}-{4:4}, at: lapbeth_new_device drivers/net/wan/lapbether.c:415 [inline]
ffff88802db40d30 (&dev->lock){+.+.}-{4:4}, at: lapbeth_device_event+0x766/0xa20 drivers/net/wan/lapbether.c:460
but task is already holding lock:
ffff8880616e4d30 (&dev->lock){+.+.}-{4:4}, at: netdev_lock include/linux/netdevice.h:2751 [inline]
ffff8880616e4d30 (&dev->lock){+.+.}-{4:4}, at: netdev_lock_ops include/net/netdev_lock.h:42 [inline]
ffff8880616e4d30 (&dev->lock){+.+.}-{4:4}, at: dev_change_flags+0x120/0x270 net/core/dev_api.c:67
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 dhcpcd/5505:
#0: ffffffff900fbc48 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_lock include/linux/rtnetlink.h:130 [inline]
#0: ffffffff900fbc48 (rtnl_mutex){+.+.}-{4:4}, at: devinet_ioctl+0x34e/0x1d80 net/ipv4/devinet.c:1121
#1: ffff8880616e4d30 (&dev->lock){+.+.}-{4:4}, at: netdev_lock include/linux/netdevice.h:2751 [inline]
#1: ffff8880616e4d30 (&dev->lock){+.+.}-{4:4}, at: netdev_lock_ops include/net/netdev_lock.h:42 [inline]
#1: ffff8880616e4d30 (&dev->lock){+.+.}-{4:4}, at: dev_change_flags+0x120/0x270 net/core/dev_api.c:67
stack backtrace:
CPU: 1 UID: 0 PID: 5505 Comm: dhcpcd Not tainted 6.14.0-syzkaller-g0c2623cef4f4 #0 PREEMPT(full)
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+0x2be/0x2d0 kernel/locking/lockdep.c:3042
check_deadlock kernel/locking/lockdep.c:3094 [inline]
validate_chain+0x928/0x24e0 kernel/locking/lockdep.c:3896
__lock_acquire+0xad5/0xd80 kernel/locking/lockdep.c:5235
lock_acquire+0x116/0x2f0 kernel/locking/lockdep.c:5866
__mutex_lock_common kernel/locking/mutex.c:601 [inline]
__mutex_lock+0x1a5/0x10c0 kernel/locking/mutex.c:746
netdev_lock include/linux/netdevice.h:2751 [inline]
netif_napi_add_weight include/linux/netdevice.h:2783 [inline]
lapbeth_new_device drivers/net/wan/lapbether.c:415 [inline]
lapbeth_device_event+0x766/0xa20 drivers/net/wan/lapbether.c:460
notifier_call_chain+0x1a5/0x3f0 kernel/notifier.c:85
__dev_notify_flags+0x209/0x410 net/core/dev.c:-1
netif_change_flags+0xf0/0x1a0 net/core/dev.c:9438
dev_change_flags+0x146/0x270 net/core/dev_api.c:68
devinet_ioctl+0xea4/0x1d80 net/ipv4/devinet.c:1200
inet_ioctl+0x3d9/0x4f0 net/ipv4/af_inet.c:1001
sock_do_ioctl+0x15a/0x490 net/socket.c:1190
sock_ioctl+0x644/0x900 net/socket.c:1311
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:906 [inline]
__se_sys_ioctl+0xf1/0x160 fs/ioctl.c:892
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xf3/0x230 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f39a6387d49
Code: 5c c3 48 8d 44 24 08 48 89 54 24 e0 48 89 44 24 c0 48 8d 44 24 d0 48 89 44 24 c8 b8 10 00 00 00 c7 44 24 b8 10 00 00 00 0f 05 <41> 89 c0 3d 00 f0 ff ff 76 10 48 8b 15 ae 60 0d 00 f7 d8 41 83 c8
RSP: 002b:00007ffd9a2de2a8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f39a62b96c0 RCX: 00007f39a6387d49
RDX: 00007ffd9a2ee498 RSI: 0000000000008914 RDI: 000000000000000c
RBP: 00007ffd9a2fe658 R08: 00007ffd9a2ee458 R09: 00007ffd9a2ee408
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffd9a2ee498 R14: 0000000000000028 R15: 0000000000008914
</TASK>