=============================
WARNING: suspicious RCU usage
6.10.0-rc2-syzkaller-00230-g5add2f728846 #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
3 locks held by swapper/1/0:
 #0: ffffc90000a18c00 ((&p->forward_delay_timer)){+.-.}-{0:0}, at: call_timer_fn+0xc0/0x650 kernel/time/timer.c:1789
 #1: ffff888027baccb8 (&br->lock){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:351 [inline]
 #1: ffff888027baccb8 (&br->lock){+.-.}-{2:2}, at: br_forward_delay_timer_expired+0x50/0x440 net/bridge/br_stp_timer.c:86
 #2: ffffffff8e333fa0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:329 [inline]
 #2: ffffffff8e333fa0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:781 [inline]
 #2: ffffffff8e333fa0 (rcu_read_lock){....}-{1:2}, at: br_mst_set_state+0x171/0x7a0 net/bridge/br_mst.c:105

stack backtrace:
CPU: 1 PID: 0 Comm: swapper/1 Not tainted 6.10.0-rc2-syzkaller-00230-g5add2f728846 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/02/2024
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+0x29e/0x7a0 net/bridge/br_mst.c:106
 br_set_state+0x28a/0x7b0 net/bridge/br_stp.c:47
 br_forward_delay_timer_expired+0x9a/0x440 net/bridge/br_stp_timer.c:92
 call_timer_fn+0x18e/0x650 kernel/time/timer.c:1792
 expire_timers kernel/time/timer.c:1843 [inline]
 __run_timers kernel/time/timer.c:2417 [inline]
 __run_timer_base+0x66a/0x8e0 kernel/time/timer.c:2428
 run_timer_base kernel/time/timer.c:2437 [inline]
 run_timer_softirq+0xb7/0x170 kernel/time/timer.c:2447
 handle_softirqs+0x2c4/0x970 kernel/softirq.c:554
 __do_softirq kernel/softirq.c:588 [inline]
 invoke_softirq kernel/softirq.c:428 [inline]
 __irq_exit_rcu+0xf4/0x1c0 kernel/softirq.c:637
 irq_exit_rcu+0x9/0x30 kernel/softirq.c:649
 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 00 d5 03 00 48 f7 00 08 00 00 00 75 10 66 90 0f 00 2d 25 c5 a2 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:ffffc900001a7d08 EFLAGS: 00000246
RAX: ffff8880176b0000 RBX: ffff8880186e7864 RCX: 0000000000035cc9
RDX: 0000000000000001 RSI: ffff8880186e7800 RDI: ffff8880186e7864
RBP: 000000000003a5b8 R08: ffff8880b9537d0b R09: 1ffff110172a6fa1
R10: dffffc0000000000 R11: ffffffff8b86b9f0 R12: ffff88801b769800
R13: 0000000000000000 R14: 0000000000000001 R15: ffffffff8eace280
 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 2(bridge_slave_1) entered forwarding 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 00 d5 	mov    %gs:0x3d500,%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 25 c5 a2 00 	verw   0xa2c525(%rip)        # 0xa2c549
  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