============================================
WARNING: possible recursive locking detected
syzkaller #0 Not tainted
--------------------------------------------
swapper/0/0 is trying to acquire lock:
ffff88802cbbd5e0 (&br->multicast_lock){+.-.}-{3:3}, at: spin_lock include/linux/spinlock.h:342 [inline]
ffff88802cbbd5e0 (&br->multicast_lock){+.-.}-{3:3}, at: br_ip4_multicast_query net/bridge/br_multicast.c:3498 [inline]
ffff88802cbbd5e0 (&br->multicast_lock){+.-.}-{3:3}, at: br_multicast_ipv4_rcv net/bridge/br_multicast.c:3912 [inline]
ffff88802cbbd5e0 (&br->multicast_lock){+.-.}-{3:3}, at: br_multicast_rcv+0x2a6d/0x7640 net/bridge/br_multicast.c:4028
but task is already holding lock:
ffff88805684d5e0 (&br->multicast_lock){+.-.}-{3:3}, at: spin_lock include/linux/spinlock.h:342 [inline]
ffff88805684d5e0 (&br->multicast_lock){+.-.}-{3:3}, at: br_multicast_port_query_expired net/bridge/br_multicast.c:1901 [inline]
ffff88805684d5e0 (&br->multicast_lock){+.-.}-{3:3}, at: br_ip4_multicast_port_query_expired+0x68/0x380 net/bridge/br_multicast.c:1920
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0
----
lock(&br->multicast_lock);
lock(&br->multicast_lock);
*** DEADLOCK ***
May be due to missing lock nesting notation
6 locks held by swapper/0/0:
#0: ffffc90000007cc0 ((&pmctx->ip4_own_query.timer)){+.-.}-{0:0}, at: call_timer_fn+0xd4/0x5e0 kernel/time/timer.c:1745
#1: ffff88805684d5e0 (&br->multicast_lock){+.-.}-{3:3}, at: spin_lock include/linux/spinlock.h:342 [inline]
#1: ffff88805684d5e0 (&br->multicast_lock){+.-.}-{3:3}, at: br_multicast_port_query_expired net/bridge/br_multicast.c:1901 [inline]
#1: ffff88805684d5e0 (&br->multicast_lock){+.-.}-{3:3}, at: br_ip4_multicast_port_query_expired+0x68/0x380 net/bridge/br_multicast.c:1920
#2: ffffffff8e95cd00 (rcu_read_lock_bh){....}-{1:3}, at: local_bh_disable include/linux/bottom_half.h:20 [inline]
#2: ffffffff8e95cd00 (rcu_read_lock_bh){....}-{1:3}, at: rcu_read_lock_bh include/linux/rcupdate.h:891 [inline]
#2: ffffffff8e95cd00 (rcu_read_lock_bh){....}-{1:3}, at: __dev_queue_xmit+0x2b6/0x3950 net/core/dev.c:4792
#3: ffffffff8e95cca0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:300 [inline]
#3: ffffffff8e95cca0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:838 [inline]
#3: ffffffff8e95cca0 (rcu_read_lock){....}-{1:3}, at: bond_start_xmit+0xb4/0x1900 drivers/net/bonding/bond_main.c:5591
#4: ffffffff8e95cd00 (rcu_read_lock_bh){....}-{1:3}, at: local_bh_disable include/linux/bottom_half.h:20 [inline]
#4: ffffffff8e95cd00 (rcu_read_lock_bh){....}-{1:3}, at: rcu_read_lock_bh include/linux/rcupdate.h:891 [inline]
#4: ffffffff8e95cd00 (rcu_read_lock_bh){....}-{1:3}, at: __dev_queue_xmit+0x2b6/0x3950 net/core/dev.c:4792
#5: ffffffff8e95cca0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:300 [inline]
#5: ffffffff8e95cca0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:838 [inline]
#5: ffffffff8e95cca0 (rcu_read_lock){....}-{1:3}, at: br_dev_xmit+0x193/0x1990 net/bridge/br_device.c:52
stack backtrace:
CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
Call Trace:
dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
print_deadlock_bug+0x279/0x290 kernel/locking/lockdep.c:3041
check_deadlock kernel/locking/lockdep.c:3093 [inline]
validate_chain kernel/locking/lockdep.c:3895 [inline]
__lock_acquire+0x253f/0x2cf0 kernel/locking/lockdep.c:5237
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_ip4_multicast_query net/bridge/br_multicast.c:3498 [inline]
br_multicast_ipv4_rcv net/bridge/br_multicast.c:3912 [inline]
br_multicast_rcv+0x2a6d/0x7640 net/bridge/br_multicast.c:4028
br_dev_xmit+0xb67/0x1990 net/bridge/br_device.c:98
__netdev_start_xmit include/linux/netdevice.h:5379 [inline]
netdev_start_xmit include/linux/netdevice.h:5388 [inline]
xmit_one net/core/dev.c:3888 [inline]
dev_hard_start_xmit+0x2cd/0x830 net/core/dev.c:3904
__dev_queue_xmit+0x14d9/0x3950 net/core/dev.c:4871
__bond_start_xmit drivers/net/bonding/bond_main.c:-1 [inline]
bond_start_xmit+0xd5c/0x1900 drivers/net/bonding/bond_main.c:5593
__netdev_start_xmit include/linux/netdevice.h:5379 [inline]
netdev_start_xmit include/linux/netdevice.h:5388 [inline]
xmit_one net/core/dev.c:3888 [inline]
dev_hard_start_xmit+0x2cd/0x830 net/core/dev.c:3904
__dev_queue_xmit+0x14d9/0x3950 net/core/dev.c:4871
dev_queue_xmit include/linux/netdevice.h:3429 [inline]
br_dev_queue_push_xmit+0x370/0x4b0 net/bridge/br_forward.c:53
NF_HOOK include/linux/netfilter.h:318 [inline]
__br_multicast_send_query+0x3100/0x4840 net/bridge/br_multicast.c:1805
br_multicast_send_query+0x509/0x6b0 net/bridge/br_multicast.c:1884
br_multicast_port_query_expired net/bridge/br_multicast.c:1909 [inline]
br_ip4_multicast_port_query_expired+0x2ab/0x380 net/bridge/br_multicast.c:1920
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
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1061 [inline]
sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1061
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
RIP: 0010:schedule_debug kernel/sched/core.c:5947 [inline]
RIP: 0010:__schedule+0x17d/0x5740 kernel/sched/core.c:7039
Code: 2b 49 8d 5d 20 48 89 d8 48 c1 e8 03 42 80 3c 30 00 74 08 48 89 df e8 62 37 85 f6 48 8b 1b 48 89 d8 48 c1 e8 03 42 80 3c 30 00 <74> 08 48 89 df e8 49 37 85 f6 48 81 3b 9d 6e ac 57 0f 85 35 1d 00
RSP: 0018:ffffffff8e607ba0 EFLAGS: 00000246
RAX: 1ffffffff1cc0000 RBX: ffffffff8e600000 RCX: 0000000000000001
RDX: 0000000000000000 RSI: ffffffff8c28b740 RDI: ffffffff8c28b700
RBP: ffffffff8e607db0 R08: ffffffff903135f7 R09: 1ffffffff20626be
R10: dffffc0000000000 R11: fffffbfff20626bf R12: 00000000ffffffff
R13: ffffffff8e692ec0 R14: dffffc0000000000 R15: ffff888125276000
schedule_idle+0x51/0x90 kernel/sched/core.c:7309
do_idle+0x58a/0x5f0 kernel/sched/idle.c:381
cpu_startup_entry+0x43/0x60 kernel/sched/idle.c:451
rest_init+0x2de/0x300 init/main.c:762
start_kernel+0x38a/0x3e0 init/main.c:1220
x86_64_start_reservations+0x24/0x30 arch/x86/kernel/head64.c:310
x86_64_start_kernel+0x143/0x1c0 arch/x86/kernel/head64.c:291
common_startup_64+0x13e/0x147
----------------
Code disassembly (best guess):
0: 2b 49 8d sub -0x73(%rcx),%ecx
3: 5d pop %rbp
4: 20 48 89 and %cl,-0x77(%rax)
7: d8 48 c1 fmuls -0x3f(%rax)
a: e8 03 42 80 3c call 0x3c804212
f: 30 00 xor %al,(%rax)
11: 74 08 je 0x1b
13: 48 89 df mov %rbx,%rdi
16: e8 62 37 85 f6 call 0xf685377d
1b: 48 8b 1b mov (%rbx),%rbx
1e: 48 89 d8 mov %rbx,%rax
21: 48 c1 e8 03 shr $0x3,%rax
25: 42 80 3c 30 00 cmpb $0x0,(%rax,%r14,1)
* 2a: 74 08 je 0x34 <-- trapping instruction
2c: 48 89 df mov %rbx,%rdi
2f: e8 49 37 85 f6 call 0xf685377d
34: 48 81 3b 9d 6e ac 57 cmpq $0x57ac6e9d,(%rbx)
3b: 0f .byte 0xf
3c: 85 .byte 0x85
3d: 35 .byte 0x35
3e: 1d .byte 0x1d