=============================
WARNING: suspicious RCU usage
6.9.0-rc6-syzkaller-00133-g19e35f24750d #0 Not tainted
-----------------------------
net/bridge/br_private.h:1599 suspicious rcu_dereference_protected() usage!

other info that might help us debug this:


rcu_scheduler_active = 2, debug_locks = 1
2 locks held by swapper/1/0:
 #0: ffffc90000a08c00 ((&p->forward_delay_timer)){+.-.}-{0:0}, at: call_timer_fn+0xc0/0x650 kernel/time/timer.c:1790
 #1: ffff888064f78cb8 (&br->lock){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:351 [inline]
 #1: ffff888064f78cb8 (&br->lock){+.-.}-{2:2}, at: br_forward_delay_timer_expired+0x50/0x440 net/bridge/br_stp_timer.c:86

stack backtrace:
CPU: 1 PID: 0 Comm: swapper/1 Not tainted 6.9.0-rc6-syzkaller-00133-g19e35f24750d #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
Call Trace:
 <IRQ>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:114
 lockdep_rcu_suspicious+0x221/0x340 kernel/locking/lockdep.c:6712
 nbp_vlan_group net/bridge/br_private.h:1599 [inline]
 br_mst_set_state+0x1ea/0x650 net/bridge/br_mst.c:105
 br_set_state+0x28a/0x7b0 net/bridge/br_stp.c:47
 br_forward_delay_timer_expired+0x176/0x440 net/bridge/br_stp_timer.c:88
 call_timer_fn+0x18e/0x650 kernel/time/timer.c:1793
 expire_timers kernel/time/timer.c:1844 [inline]
 __run_timers kernel/time/timer.c:2418 [inline]
 __run_timer_base+0x66a/0x8e0 kernel/time/timer.c:2429
 run_timer_base kernel/time/timer.c:2438 [inline]
 run_timer_softirq+0xb7/0x170 kernel/time/timer.c:2448
 __do_softirq+0x2c6/0x980 kernel/softirq.c:554
 invoke_softirq kernel/softirq.c:428 [inline]
 __irq_exit_rcu+0xf2/0x1c0 kernel/softirq.c:633
 irq_exit_rcu+0x9/0x30 kernel/softirq.c:645
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1043 [inline]
 sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1043
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702
RIP: 0010:native_irq_disable arch/x86/include/asm/irqflags.h:37 [inline]
RIP: 0010:arch_local_irq_disable arch/x86/include/asm/irqflags.h:72 [inline]
RIP: 0010:acpi_safe_halt+0x21/0x30 drivers/acpi/processor_idle.c:113
Code: 90 90 90 90 90 90 90 90 90 65 48 8b 04 25 c0 d3 03 00 48 f7 00 08 00 00 00 75 10 66 90 0f 00 2d c5 a4 a8 00 f3 0f 1e fa fb f4 <fa> c3 cc cc cc cc 66 0f 1f 84 00 00 00 00 00 90 90 90 90 90 90 90
RSP: 0018:ffffc90000197d08 EFLAGS: 00000246
RAX: ffff8880176c5a00 RBX: ffff8880176ed864 RCX: 0000000000038cc1
RDX: 0000000000000001 RSI: ffff8880176ed800 RDI: ffff8880176ed864
RBP: 000000000003a478 R08: ffff8880b9537ccb R09: 1ffff110172a6f99
R10: dffffc0000000000 R11: ffffffff8b80a030 R12: ffff888015704800
R13: 0000000000000000 R14: 0000000000000001 R15: ffffffff8eac38a0
 acpi_idle_enter+0xe4/0x140 drivers/acpi/processor_idle.c:707
 cpuidle_enter_state+0x112/0x480 drivers/cpuidle/cpuidle.c:267
 cpuidle_enter+0x5d/0xa0 drivers/cpuidle/cpuidle.c:388
 call_cpuidle kernel/sched/idle.c:155 [inline]
 cpuidle_idle_call kernel/sched/idle.c:236 [inline]
 do_idle+0x375/0x5d0 kernel/sched/idle.c:332
 cpu_startup_entry+0x42/0x60 kernel/sched/idle.c:430
 start_secondary+0x100/0x100 arch/x86/kernel/smpboot.c:313
 common_startup_64+0x13e/0x147
 </TASK>
bridge0: port 1(bridge_slave_0) entered learning state
bridge0: port 2(bridge_slave_1) entered learning state
bridge0: port 1(bridge_slave_0) entered learning state
bridge0: port 1(bridge_slave_0) entered learning state
bridge0: port 2(bridge_slave_1) entered learning state
----------------
Code disassembly (best guess):
   0:	90                   	nop
   1:	90                   	nop
   2:	90                   	nop
   3:	90                   	nop
   4:	90                   	nop
   5:	90                   	nop
   6:	90                   	nop
   7:	90                   	nop
   8:	90                   	nop
   9:	65 48 8b 04 25 c0 d3 	mov    %gs:0x3d3c0,%rax
  10:	03 00
  12:	48 f7 00 08 00 00 00 	testq  $0x8,(%rax)
  19:	75 10                	jne    0x2b
  1b:	66 90                	xchg   %ax,%ax
  1d:	0f 00 2d c5 a4 a8 00 	verw   0xa8a4c5(%rip)        # 0xa8a4e9
  24:	f3 0f 1e fa          	endbr64
  28:	fb                   	sti
  29:	f4                   	hlt
* 2a:	fa                   	cli <-- trapping instruction
  2b:	c3                   	ret
  2c:	cc                   	int3
  2d:	cc                   	int3
  2e:	cc                   	int3
  2f:	cc                   	int3
  30:	66 0f 1f 84 00 00 00 	nopw   0x0(%rax,%rax,1)
  37:	00 00
  39:	90                   	nop
  3a:	90                   	nop
  3b:	90                   	nop
  3c:	90                   	nop
  3d:	90                   	nop
  3e:	90                   	nop
  3f:	90                   	nop