* [syzbot] [net?] possible deadlock in br_forward_delay_timer_expired (5)
@ 2026-04-18 5:30 syzbot
0 siblings, 0 replies; only message in thread
From: syzbot @ 2026-04-18 5:30 UTC (permalink / raw)
To: andrew+netdev, davem, edumazet, jv, kuba, linux-kernel, netdev,
pabeni, syzkaller-bugs
Hello,
syzbot found the following issue on:
HEAD commit: 43cfbdda5af6 Merge tag 'for-linus-iommufd' of git://git.ke..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=100a4702580000
kernel config: https://syzkaller.appspot.com/x/.config?x=8195c5b22e79c2cf
dashboard link: https://syzkaller.appspot.com/bug?extid=a7f25fd06ad99e9379e4
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
Unfortunately, I don't have any reproducer for this issue yet.
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/848e46852283/disk-43cfbdda.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/24283dbdc318/vmlinux-43cfbdda.xz
kernel image: https://storage.googleapis.com/syzbot-assets/f91b3fadd31d/bzImage-43cfbdda.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+a7f25fd06ad99e9379e4@syzkaller.appspotmail.com
netlink: 16 bytes leftover after parsing attributes in process `syz.3.6945'.
=====================================================
WARNING: SOFTIRQ-safe -> SOFTIRQ-unsafe lock order detected
syzkaller #0 Tainted: G L
-----------------------------------------------------
syz.3.6945/21491 [HC0[0]:SC0[2]:HE1:SE0] is trying to acquire:
ffff888035200e98 (&bond->stats_lock/2){+.+.}-{3:3}, at: bond_get_stats+0x458/0x740 drivers/net/bonding/bond_main.c:4514
and this task is already holding:
ffff888036758e18 (&br->lock){+.-.}-{3:3}, at: spin_lock_bh include/linux/spinlock.h:348 [inline]
ffff888036758e18 (&br->lock){+.-.}-{3:3}, at: br_port_slave_changelink+0x3d/0x150 net/bridge/br_netlink.c:1212
which would create a new lock dependency:
(&br->lock){+.-.}-{3:3} -> (&bond->stats_lock/2){+.+.}-{3:3}
but this new dependency connects a SOFTIRQ-irq-safe lock:
(&br->lock){+.-.}-{3:3}
... which became SOFTIRQ-irq-safe at:
lock_acquire+0x106/0x350 kernel/locking/lockdep.c:5868
__raw_spin_lock include/linux/spinlock_api_smp.h:158 [inline]
_raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:158
spin_lock include/linux/spinlock.h:342 [inline]
br_forward_delay_timer_expired+0x4f/0x460 net/bridge/br_stp_timer.c:88
call_timer_fn+0x192/0x5e0 kernel/time/timer.c:1748
expire_timers kernel/time/timer.c:1799 [inline]
__run_timers kernel/time/timer.c:2374 [inline]
__run_timer_base+0x652/0x8b0 kernel/time/timer.c:2386
run_timer_base kernel/time/timer.c:2395 [inline]
run_timer_softirq+0xb7/0x170 kernel/time/timer.c:2405
handle_softirqs+0x22a/0x840 kernel/softirq.c:622
__do_softirq kernel/softirq.c:656 [inline]
invoke_softirq kernel/softirq.c:496 [inline]
__irq_exit_rcu+0xca/0x220 kernel/softirq.c:735
irq_exit_rcu+0x9/0x30 kernel/softirq.c:752
common_interrupt+0xbb/0xe0 arch/x86/kernel/irq.c:326
asm_common_interrupt+0x26/0x40 arch/x86/include/asm/idtentry.h:688
finish_task_switch+0x427/0xbe0 kernel/sched/core.c:5244
context_switch kernel/sched/core.c:5390 [inline]
__schedule+0x17bc/0x5680 kernel/sched/core.c:7188
__schedule_loop kernel/sched/core.c:7267 [inline]
schedule+0x164/0x360 kernel/sched/core.c:7282
smpboot_thread_fn+0x5bc/0xa50 kernel/smpboot.c:156
kthread+0x388/0x470 kernel/kthread.c:436
ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
to a SOFTIRQ-irq-unsafe lock:
(&bond->stats_lock/2){+.+.}-{3:3}
... which became SOFTIRQ-irq-unsafe at:
...
lock_acquire+0x106/0x350 kernel/locking/lockdep.c:5868
_raw_spin_lock_nested+0x32/0x50 kernel/locking/spinlock.c:382
bond_get_stats+0x458/0x740 drivers/net/bonding/bond_main.c:4514
dev_get_stats+0xb4/0xa50 net/core/dev.c:11916
rtnl_fill_stats+0x47/0x8c0 net/core/rtnetlink.c:1506
rtnl_fill_ifinfo+0x1840/0x20f0 net/core/rtnetlink.c:2155
rtmsg_ifinfo_build_skb+0x17d/0x260 net/core/rtnetlink.c:4452
rtmsg_ifinfo_event net/core/rtnetlink.c:4485 [inline]
rtnetlink_event+0x1b7/0x270 net/core/rtnetlink.c:7054
notifier_call_chain+0x1ad/0x3d0 kernel/notifier.c:85
call_netdevice_notifiers_extack net/core/dev.c:2287 [inline]
call_netdevice_notifiers net/core/dev.c:2301 [inline]
netdev_features_change net/core/dev.c:1590 [inline]
netdev_change_features net/core/dev.c:11155 [inline]
netdev_compute_master_upper_features+0x91e/0xac0 net/core/dev.c:12913
bond_enslave+0x21cc/0x3c10 drivers/net/bonding/bond_main.c:2276
do_set_master+0x533/0x6d0 net/core/rtnetlink.c:2985
do_setlink+0x1018/0x4590 net/core/rtnetlink.c:3187
rtnl_changelink net/core/rtnetlink.c:3798 [inline]
__rtnl_newlink net/core/rtnetlink.c:3971 [inline]
rtnl_newlink+0x15ad/0x1bb0 net/core/rtnetlink.c:4108
rtnetlink_rcv_msg+0x7d5/0xbe0 net/core/rtnetlink.c:6994
netlink_rcv_skb+0x232/0x4b0 net/netlink/af_netlink.c:2550
netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
netlink_unicast+0x75c/0x8e0 net/netlink/af_netlink.c:1344
netlink_sendmsg+0x813/0xb40 net/netlink/af_netlink.c:1894
sock_sendmsg_nosec net/socket.c:787 [inline]
__sock_sendmsg net/socket.c:802 [inline]
____sys_sendmsg+0x972/0x9f0 net/socket.c:2698
___sys_sendmsg+0x2a5/0x360 net/socket.c:2752
__sys_sendmsg net/socket.c:2784 [inline]
__do_sys_sendmsg net/socket.c:2789 [inline]
__se_sys_sendmsg net/socket.c:2787 [inline]
__x64_sys_sendmsg+0x1bd/0x2a0 net/socket.c:2787
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x15f/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
other info that might help us debug this:
Possible interrupt unsafe locking scenario:
CPU0 CPU1
---- ----
lock(&bond->stats_lock/2);
local_irq_disable();
lock(&br->lock);
lock(&bond->stats_lock/2);
<Interrupt>
lock(&br->lock);
*** DEADLOCK ***
3 locks held by syz.3.6945/21491:
#0: ffffffff8fdddc80 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_lock net/core/rtnetlink.c:80 [inline]
#0: ffffffff8fdddc80 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_nets_lock net/core/rtnetlink.c:341 [inline]
#0: ffffffff8fdddc80 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_newlink+0x883/0x1bb0 net/core/rtnetlink.c:4107
#1: ffff888036758e18 (&br->lock){+.-.}-{3:3}, at: spin_lock_bh include/linux/spinlock.h:348 [inline]
#1: ffff888036758e18 (&br->lock){+.-.}-{3:3}, at: br_port_slave_changelink+0x3d/0x150 net/bridge/br_netlink.c:1212
#2: ffffffff8e95cb20 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:300 [inline]
#2: ffffffff8e95cb20 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:838 [inline]
#2: ffffffff8e95cb20 (rcu_read_lock){....}-{1:3}, at: bond_get_stats+0x11a/0x740 drivers/net/bonding/bond_main.c:4509
the dependencies between SOFTIRQ-irq-safe lock and the holding lock:
-> (&br->lock){+.-.}-{3:3} {
HARDIRQ-ON-W at:
lock_acquire+0x106/0x350 kernel/locking/lockdep.c:5868
__raw_spin_lock_bh include/linux/spinlock_api_smp.h:150 [inline]
_raw_spin_lock_bh+0x36/0x50 kernel/locking/spinlock.c:182
spin_lock_bh include/linux/spinlock.h:348 [inline]
br_add_if+0xa99/0xeb0 net/bridge/br_if.c:668
do_set_master+0x533/0x6d0 net/core/rtnetlink.c:2985
do_setlink+0x1018/0x4590 net/core/rtnetlink.c:3187
rtnl_changelink net/core/rtnetlink.c:3798 [inline]
__rtnl_newlink net/core/rtnetlink.c:3971 [inline]
rtnl_newlink+0x15ad/0x1bb0 net/core/rtnetlink.c:4108
rtnetlink_rcv_msg+0x7d5/0xbe0 net/core/rtnetlink.c:6994
netlink_rcv_skb+0x232/0x4b0 net/netlink/af_netlink.c:2550
netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
netlink_unicast+0x75c/0x8e0 net/netlink/af_netlink.c:1344
netlink_sendmsg+0x813/0xb40 net/netlink/af_netlink.c:1894
sock_sendmsg_nosec net/socket.c:787 [inline]
__sock_sendmsg net/socket.c:802 [inline]
__sys_sendto+0x672/0x710 net/socket.c:2265
__do_sys_sendto net/socket.c:2272 [inline]
__se_sys_sendto net/socket.c:2268 [inline]
__x64_sys_sendto+0xde/0x100 net/socket.c:2268
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x15f/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
IN-SOFTIRQ-W at:
lock_acquire+0x106/0x350 kernel/locking/lockdep.c:5868
__raw_spin_lock include/linux/spinlock_api_smp.h:158 [inline]
_raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:158
spin_lock include/linux/spinlock.h:342 [inline]
br_forward_delay_timer_expired+0x4f/0x460 net/bridge/br_stp_timer.c:88
call_timer_fn+0x192/0x5e0 kernel/time/timer.c:1748
expire_timers kernel/time/timer.c:1799 [inline]
__run_timers kernel/time/timer.c:2374 [inline]
__run_timer_base+0x652/0x8b0 kernel/time/timer.c:2386
run_timer_base kernel/time/timer.c:2395 [inline]
run_timer_softirq+0xb7/0x170 kernel/time/timer.c:2405
handle_softirqs+0x22a/0x840 kernel/softirq.c:622
__do_softirq kernel/softirq.c:656 [inline]
invoke_softirq kernel/softirq.c:496 [inline]
__irq_exit_rcu+0xca/0x220 kernel/softirq.c:735
irq_exit_rcu+0x9/0x30 kernel/softirq.c:752
common_interrupt+0xbb/0xe0 arch/x86/kernel/irq.c:326
asm_common_interrupt+0x26/0x40 arch/x86/include/asm/idtentry.h:688
finish_task_switch+0x427/0xbe0 kernel/sched/core.c:5244
context_switch kernel/sched/core.c:5390 [inline]
__schedule+0x17bc/0x5680 kernel/sched/core.c:7188
__schedule_loop kernel/sched/core.c:7267 [inline]
schedule+0x164/0x360 kernel/sched/core.c:7282
smpboot_thread_fn+0x5bc/0xa50 kernel/smpboot.c:156
kthread+0x388/0x470 kernel/kthread.c:436
ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
INITIAL USE at:
lock_acquire+0x106/0x350 kernel/locking/lockdep.c:5868
__raw_spin_lock_bh include/linux/spinlock_api_smp.h:150 [inline]
_raw_spin_lock_bh+0x36/0x50 kernel/locking/spinlock.c:182
spin_lock_bh include/linux/spinlock.h:348 [inline]
br_add_if+0xa99/0xeb0 net/bridge/br_if.c:668
do_set_master+0x533/0x6d0 net/core/rtnetlink.c:2985
do_setlink+0x1018/0x4590 net/core/rtnetlink.c:3187
rtnl_changelink net/core/rtnetlink.c:3798 [inline]
__rtnl_newlink net/core/rtnetlink.c:3971 [inline]
rtnl_newlink+0x15ad/0x1bb0 net/core/rtnetlink.c:4108
rtnetlink_rcv_msg+0x7d5/0xbe0 net/core/rtnetlink.c:6994
netlink_rcv_skb+0x232/0x4b0 net/netlink/af_netlink.c:2550
netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
netlink_unicast+0x75c/0x8e0 net/netlink/af_netlink.c:1344
netlink_sendmsg+0x813/0xb40 net/netlink/af_netlink.c:1894
sock_sendmsg_nosec net/socket.c:787 [inline]
__sock_sendmsg net/socket.c:802 [inline]
__sys_sendto+0x672/0x710 net/socket.c:2265
__do_sys_sendto net/socket.c:2272 [inline]
__se_sys_sendto net/socket.c:2268 [inline]
__x64_sys_sendto+0xde/0x100 net/socket.c:2268
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x15f/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
}
... key at: [<ffffffff9aa0b240>] br_dev_setup.__key+0x0/0x20
the dependencies between the lock to be acquired
and SOFTIRQ-irq-unsafe lock:
-> (&bond->stats_lock/2){+.+.}-{3:3} {
HARDIRQ-ON-W at:
lock_acquire+0x106/0x350 kernel/locking/lockdep.c:5868
_raw_spin_lock_nested+0x32/0x50 kernel/locking/spinlock.c:382
bond_get_stats+0x458/0x740 drivers/net/bonding/bond_main.c:4514
dev_get_stats+0xb4/0xa50 net/core/dev.c:11916
rtnl_fill_stats+0x47/0x8c0 net/core/rtnetlink.c:1506
rtnl_fill_ifinfo+0x1840/0x20f0 net/core/rtnetlink.c:2155
rtmsg_ifinfo_build_skb+0x17d/0x260 net/core/rtnetlink.c:4452
rtmsg_ifinfo_event net/core/rtnetlink.c:4485 [inline]
rtnetlink_event+0x1b7/0x270 net/core/rtnetlink.c:7054
notifier_call_chain+0x1ad/0x3d0 kernel/notifier.c:85
call_netdevice_notifiers_extack net/core/dev.c:2287 [inline]
call_netdevice_notifiers net/core/dev.c:2301 [inline]
netdev_features_change net/core/dev.c:1590 [inline]
netdev_change_features net/core/dev.c:11155 [inline]
netdev_compute_master_upper_features+0x91e/0xac0 net/core/dev.c:12913
bond_enslave+0x21cc/0x3c10 drivers/net/bonding/bond_main.c:2276
do_set_master+0x533/0x6d0 net/core/rtnetlink.c:2985
do_setlink+0x1018/0x4590 net/core/rtnetlink.c:3187
rtnl_changelink net/core/rtnetlink.c:3798 [inline]
__rtnl_newlink net/core/rtnetlink.c:3971 [inline]
rtnl_newlink+0x15ad/0x1bb0 net/core/rtnetlink.c:4108
rtnetlink_rcv_msg+0x7d5/0xbe0 net/core/rtnetlink.c:6994
netlink_rcv_skb+0x232/0x4b0 net/netlink/af_netlink.c:2550
netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
netlink_unicast+0x75c/0x8e0 net/netlink/af_netlink.c:1344
netlink_sendmsg+0x813/0xb40 net/netlink/af_netlink.c:1894
sock_sendmsg_nosec net/socket.c:787 [inline]
__sock_sendmsg net/socket.c:802 [inline]
____sys_sendmsg+0x972/0x9f0 net/socket.c:2698
___sys_sendmsg+0x2a5/0x360 net/socket.c:2752
__sys_sendmsg net/socket.c:2784 [inline]
__do_sys_sendmsg net/socket.c:2789 [inline]
__se_sys_sendmsg net/socket.c:2787 [inline]
__x64_sys_sendmsg+0x1bd/0x2a0 net/socket.c:2787
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x15f/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
SOFTIRQ-ON-W at:
lock_acquire+0x106/0x350 kernel/locking/lockdep.c:5868
_raw_spin_lock_nested+0x32/0x50 kernel/locking/spinlock.c:382
bond_get_stats+0x458/0x740 drivers/net/bonding/bond_main.c:4514
dev_get_stats+0xb4/0xa50 net/core/dev.c:11916
rtnl_fill_stats+0x47/0x8c0 net/core/rtnetlink.c:1506
rtnl_fill_ifinfo+0x1840/0x20f0 net/core/rtnetlink.c:2155
rtmsg_ifinfo_build_skb+0x17d/0x260 net/core/rtnetlink.c:4452
rtmsg_ifinfo_event net/core/rtnetlink.c:4485 [inline]
rtnetlink_event+0x1b7/0x270 net/core/rtnetlink.c:7054
notifier_call_chain+0x1ad/0x3d0 kernel/notifier.c:85
call_netdevice_notifiers_extack net/core/dev.c:2287 [inline]
call_netdevice_notifiers net/core/dev.c:2301 [inline]
netdev_features_change net/core/dev.c:1590 [inline]
netdev_change_features net/core/dev.c:11155 [inline]
netdev_compute_master_upper_features+0x91e/0xac0 net/core/dev.c:12913
bond_enslave+0x21cc/0x3c10 drivers/net/bonding/bond_main.c:2276
do_set_master+0x533/0x6d0 net/core/rtnetlink.c:2985
do_setlink+0x1018/0x4590 net/core/rtnetlink.c:3187
rtnl_changelink net/core/rtnetlink.c:3798 [inline]
__rtnl_newlink net/core/rtnetlink.c:3971 [inline]
rtnl_newlink+0x15ad/0x1bb0 net/core/rtnetlink.c:4108
rtnetlink_rcv_msg+0x7d5/0xbe0 net/core/rtnetlink.c:6994
netlink_rcv_skb+0x232/0x4b0 net/netlink/af_netlink.c:2550
netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
netlink_unicast+0x75c/0x8e0 net/netlink/af_netlink.c:1344
netlink_sendmsg+0x813/0xb40 net/netlink/af_netlink.c:1894
sock_sendmsg_nosec net/socket.c:787 [inline]
__sock_sendmsg net/socket.c:802 [inline]
____sys_sendmsg+0x972/0x9f0 net/socket.c:2698
___sys_sendmsg+0x2a5/0x360 net/socket.c:2752
__sys_sendmsg net/socket.c:2784 [inline]
__do_sys_sendmsg net/socket.c:2789 [inline]
__se_sys_sendmsg net/socket.c:2787 [inline]
__x64_sys_sendmsg+0x1bd/0x2a0 net/socket.c:2787
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x15f/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
INITIAL USE at:
lock_acquire+0x106/0x350 kernel/locking/lockdep.c:5868
_raw_spin_lock_nested+0x32/0x50 kernel/locking/spinlock.c:382
bond_get_stats+0x458/0x740 drivers/net/bonding/bond_main.c:4514
dev_get_stats+0xb4/0xa50 net/core/dev.c:11916
rtnl_fill_stats+0x47/0x8c0 net/core/rtnetlink.c:1506
rtnl_fill_ifinfo+0x1840/0x20f0 net/core/rtnetlink.c:2155
rtmsg_ifinfo_build_skb+0x17d/0x260 net/core/rtnetlink.c:4452
rtmsg_ifinfo_event net/core/rtnetlink.c:4485 [inline]
rtnetlink_event+0x1b7/0x270 net/core/rtnetlink.c:7054
notifier_call_chain+0x1ad/0x3d0 kernel/notifier.c:85
call_netdevice_notifiers_extack net/core/dev.c:2287 [inline]
call_netdevice_notifiers net/core/dev.c:2301 [inline]
netdev_features_change net/core/dev.c:1590 [inline]
netdev_change_features net/core/dev.c:11155 [inline]
netdev_compute_master_upper_features+0x91e/0xac0 net/core/dev.c:12913
bond_enslave+0x21cc/0x3c10 drivers/net/bonding/bond_main.c:2276
do_set_master+0x533/0x6d0 net/core/rtnetlink.c:2985
do_setlink+0x1018/0x4590 net/core/rtnetlink.c:3187
rtnl_changelink net/core/rtnetlink.c:3798 [inline]
__rtnl_newlink net/core/rtnetlink.c:3971 [inline]
rtnl_newlink+0x15ad/0x1bb0 net/core/rtnetlink.c:4108
rtnetlink_rcv_msg+0x7d5/0xbe0 net/core/rtnetlink.c:6994
netlink_rcv_skb+0x232/0x4b0 net/netlink/af_netlink.c:2550
netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
netlink_unicast+0x75c/0x8e0 net/netlink/af_netlink.c:1344
netlink_sendmsg+0x813/0xb40 net/netlink/af_netlink.c:1894
sock_sendmsg_nosec net/socket.c:787 [inline]
__sock_sendmsg net/socket.c:802 [inline]
____sys_sendmsg+0x972/0x9f0 net/socket.c:2698
___sys_sendmsg+0x2a5/0x360 net/socket.c:2752
__sys_sendmsg net/socket.c:2784 [inline]
__do_sys_sendmsg net/socket.c:2789 [inline]
__se_sys_sendmsg net/socket.c:2787 [inline]
__x64_sys_sendmsg+0x1bd/0x2a0 net/socket.c:2787
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x15f/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
}
... key at: [<ffffffff9a825582>] bond_init.__key+0x2/0x20
... acquired at:
_raw_spin_lock_nested+0x32/0x50 kernel/locking/spinlock.c:382
bond_get_stats+0x458/0x740 drivers/net/bonding/bond_main.c:4514
dev_get_stats+0xb4/0xa50 net/core/dev.c:11916
rtnl_fill_stats+0x47/0x8c0 net/core/rtnetlink.c:1506
rtnl_fill_ifinfo+0x1840/0x20f0 net/core/rtnetlink.c:2155
rtmsg_ifinfo_build_skb+0x17d/0x260 net/core/rtnetlink.c:4452
rtmsg_ifinfo_event net/core/rtnetlink.c:4485 [inline]
rtmsg_ifinfo+0x8c/0x1a0 net/core/rtnetlink.c:4494
__dev_notify_flags+0xf2/0x310 net/core/dev.c:9845
__dev_set_promiscuity+0x27f/0x710 net/core/dev.c:9647
netif_set_promiscuity+0x50/0xe0 net/core/dev.c:9657
dev_set_promiscuity+0x126/0x260 net/core/dev_api.c:287
br_port_clear_promisc net/bridge/br_if.c:135 [inline]
br_manage_promisc+0x4db/0x560 net/bridge/br_if.c:172
nbp_update_port_count net/bridge/br_if.c:242 [inline]
br_port_flags_change+0x160/0x1f0 net/bridge/br_if.c:747
br_setport+0xc0a/0x1680 net/bridge/br_netlink.c:1000
br_port_slave_changelink+0x12f/0x150 net/bridge/br_netlink.c:1213
rtnl_changelink net/core/rtnetlink.c:3791 [inline]
__rtnl_newlink net/core/rtnetlink.c:3971 [inline]
rtnl_newlink+0x191b/0x1bb0 net/core/rtnetlink.c:4108
rtnetlink_rcv_msg+0x7d5/0xbe0 net/core/rtnetlink.c:6994
netlink_rcv_skb+0x232/0x4b0 net/netlink/af_netlink.c:2550
netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
netlink_unicast+0x75c/0x8e0 net/netlink/af_netlink.c:1344
netlink_sendmsg+0x813/0xb40 net/netlink/af_netlink.c:1894
sock_sendmsg_nosec net/socket.c:787 [inline]
__sock_sendmsg net/socket.c:802 [inline]
____sys_sendmsg+0x972/0x9f0 net/socket.c:2698
___sys_sendmsg+0x2a5/0x360 net/socket.c:2752
__sys_sendmsg net/socket.c:2784 [inline]
__do_sys_sendmsg net/socket.c:2789 [inline]
__se_sys_sendmsg net/socket.c:2787 [inline]
__x64_sys_sendmsg+0x1bd/0x2a0 net/socket.c:2787
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x15f/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
stack backtrace:
CPU: 0 UID: 0 PID: 21491 Comm: syz.3.6945 Tainted: G L syzkaller #0 PREEMPT(full)
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
Call Trace:
<TASK>
dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
print_bad_irq_dependency kernel/locking/lockdep.c:2616 [inline]
check_irq_usage kernel/locking/lockdep.c:2857 [inline]
check_prev_add kernel/locking/lockdep.c:3169 [inline]
check_prevs_add kernel/locking/lockdep.c:3284 [inline]
validate_chain kernel/locking/lockdep.c:3908 [inline]
__lock_acquire+0x2a94/0x2cf0 kernel/locking/lockdep.c:5237
lock_acquire+0x106/0x350 kernel/locking/lockdep.c:5868
_raw_spin_lock_nested+0x32/0x50 kernel/locking/spinlock.c:382
bond_get_stats+0x458/0x740 drivers/net/bonding/bond_main.c:4514
dev_get_stats+0xb4/0xa50 net/core/dev.c:11916
rtnl_fill_stats+0x47/0x8c0 net/core/rtnetlink.c:1506
rtnl_fill_ifinfo+0x1840/0x20f0 net/core/rtnetlink.c:2155
rtmsg_ifinfo_build_skb+0x17d/0x260 net/core/rtnetlink.c:4452
rtmsg_ifinfo_event net/core/rtnetlink.c:4485 [inline]
rtmsg_ifinfo+0x8c/0x1a0 net/core/rtnetlink.c:4494
__dev_notify_flags+0xf2/0x310 net/core/dev.c:9845
__dev_set_promiscuity+0x27f/0x710 net/core/dev.c:9647
netif_set_promiscuity+0x50/0xe0 net/core/dev.c:9657
dev_set_promiscuity+0x126/0x260 net/core/dev_api.c:287
br_port_clear_promisc net/bridge/br_if.c:135 [inline]
br_manage_promisc+0x4db/0x560 net/bridge/br_if.c:172
nbp_update_port_count net/bridge/br_if.c:242 [inline]
br_port_flags_change+0x160/0x1f0 net/bridge/br_if.c:747
br_setport+0xc0a/0x1680 net/bridge/br_netlink.c:1000
br_port_slave_changelink+0x12f/0x150 net/bridge/br_netlink.c:1213
rtnl_changelink net/core/rtnetlink.c:3791 [inline]
__rtnl_newlink net/core/rtnetlink.c:3971 [inline]
rtnl_newlink+0x191b/0x1bb0 net/core/rtnetlink.c:4108
rtnetlink_rcv_msg+0x7d5/0xbe0 net/core/rtnetlink.c:6994
netlink_rcv_skb+0x232/0x4b0 net/netlink/af_netlink.c:2550
netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
netlink_unicast+0x75c/0x8e0 net/netlink/af_netlink.c:1344
netlink_sendmsg+0x813/0xb40 net/netlink/af_netlink.c:1894
sock_sendmsg_nosec net/socket.c:787 [inline]
__sock_sendmsg net/socket.c:802 [inline]
____sys_sendmsg+0x972/0x9f0 net/socket.c:2698
___sys_sendmsg+0x2a5/0x360 net/socket.c:2752
__sys_sendmsg net/socket.c:2784 [inline]
__do_sys_sendmsg net/socket.c:2789 [inline]
__se_sys_sendmsg net/socket.c:2787 [inline]
__x64_sys_sendmsg+0x1bd/0x2a0 net/socket.c:2787
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x15f/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f779019c819
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:00007f7791124028 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f7790415fa0 RCX: 00007f779019c819
RDX: 0000000000008002 RSI: 0000200000000340 RDI: 0000000000000003
RBP: 00007f7790232c91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f7790416038 R14: 00007f7790415fa0 R15: 00007f779053fa48
</TASK>
---
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2026-04-18 5:30 [syzbot] [net?] possible deadlock in br_forward_delay_timer_expired (5) syzbot
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