syzbot

rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 	1-....: (1 GPs behind) idle=63d/1/0x4000000000000000 softirq=55789/55793 fqs=5246 
	(t=10502 jiffies g=82001 q=1401)
NMI backtrace for cpu 1
CPU: 1 PID: 1223 Comm: aoe_tx0 Not tainted 5.18.0-rc4-syzkaller-00006-gd615b5416f8a #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 <IRQ>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
 nmi_cpu_backtrace.cold+0x47/0x144 lib/nmi_backtrace.c:111
 nmi_trigger_cpumask_backtrace+0x1e6/0x230 lib/nmi_backtrace.c:62
 trigger_single_cpu_backtrace include/linux/nmi.h:164 [inline]
 rcu_dump_cpu_stacks+0x262/0x3f0 kernel/rcu/tree_stall.h:343
 print_cpu_stall kernel/rcu/tree_stall.h:639 [inline]
 check_cpu_stall kernel/rcu/tree_stall.h:723 [inline]
 rcu_pending kernel/rcu/tree.c:3923 [inline]
 rcu_sched_clock_irq.cold+0xa1/0x8d6 kernel/rcu/tree.c:2625
 update_process_times+0x16d/0x200 kernel/time/timer.c:1788
 tick_sched_handle+0x9b/0x180 kernel/time/tick-sched.c:243
 tick_sched_timer+0xee/0x120 kernel/time/tick-sched.c:1473
 __run_hrtimer kernel/time/hrtimer.c:1685 [inline]
 __hrtimer_run_queues+0x1c0/0xe50 kernel/time/hrtimer.c:1749
 hrtimer_interrupt+0x31c/0x790 kernel/time/hrtimer.c:1811
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1086 [inline]
 __sysvec_apic_timer_interrupt+0x146/0x530 arch/x86/kernel/apic/apic.c:1103
 sysvec_apic_timer_interrupt+0x8e/0xc0 arch/x86/kernel/apic/apic.c:1097
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:645
RIP: 0010:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:152 [inline]
RIP: 0010:_raw_spin_unlock_irqrestore+0x38/0x70 kernel/locking/spinlock.c:194
Code: 74 24 10 e8 3a 3f f0 f7 48 89 ef e8 82 be f0 f7 81 e3 00 02 00 00 75 25 9c 58 f6 c4 02 75 2d 48 85 db 74 01 fb bf 01 00 00 00 <e8> 13 de e3 f7 65 8b 05 5c e2 95 76 85 c0 74 0a 5b 5d c3 e8 40 20
RSP: 0018:ffffc900055cfa90 EFLAGS: 00000206
RAX: 0000000000000002 RBX: 0000000000000200 RCX: 1ffffffff2018546
RDX: 0000000000000000 RSI: 0000000000000202 RDI: 0000000000000001
RBP: ffffffff90883678 R08: 0000000000000001 R09: ffffffff9005ba17
R10: 0000000000000001 R11: 0000000000000001 R12: 0000000000000020
R13: ffff88801a07f8b0 R14: ffff88801ba20fe0 R15: 0000000000000001
 spin_unlock_irqrestore include/linux/spinlock.h:404 [inline]
 uart_write+0x423/0x570 drivers/tty/serial/serial_core.c:569
 handle_tx+0x204/0x610 drivers/net/caif/caif_serial.c:236
 __netdev_start_xmit include/linux/netdevice.h:4778 [inline]
 netdev_start_xmit include/linux/netdevice.h:4792 [inline]
 xmit_one net/core/dev.c:3532 [inline]
 dev_hard_start_xmit+0x1eb/0x920 net/core/dev.c:3548
 __dev_queue_xmit+0x2b81/0x39c0 net/core/dev.c:4176
 tx+0x68/0xb0 drivers/block/aoe/aoenet.c:63
 kthread+0x1e7/0x3b0 drivers/block/aoe/aoecmd.c:1229
 kthread+0x2e9/0x3a0 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:298
 </TASK>
----------------
Code disassembly (best guess):
   0:	74 24                	je     0x26
   2:	10 e8                	adc    %ch,%al
   4:	3a 3f                	cmp    (%rdi),%bh
   6:	f0 f7 48 89 ef e8 82 	lock testl $0xbe82e8ef,-0x77(%rax)
   d:	be
   e:	f0 f7 81 e3 00 02 00 	lock testl $0x9c257500,0x200e3(%rcx)
  15:	00 75 25 9c
  19:	58                   	pop    %rax
  1a:	f6 c4 02             	test   $0x2,%ah
  1d:	75 2d                	jne    0x4c
  1f:	48 85 db             	test   %rbx,%rbx
  22:	74 01                	je     0x25
  24:	fb                   	sti
  25:	bf 01 00 00 00       	mov    $0x1,%edi
* 2a:	e8 13 de e3 f7       	callq  0xf7e3de42 <-- trapping instruction
  2f:	65 8b 05 5c e2 95 76 	mov    %gs:0x7695e25c(%rip),%eax        # 0x7695e292
  36:	85 c0                	test   %eax,%eax
  38:	74 0a                	je     0x44
  3a:	5b                   	pop    %rbx
  3b:	5d                   	pop    %rbp
  3c:	c3                   	retq
  3d:	e8                   	.byte 0xe8
  3e:	40                   	rex
  3f:	20                   	.byte 0x20