rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 	0-....: (3870 ticks this GP) idle=3c6/1/0x4000000000000000 softirq=139664/139667 fqs=2881 
	(t=10500 jiffies g=219401 q=9986)
NMI backtrace for cpu 0
CPU: 0 PID: 13 Comm: ksoftirqd/0 Not tainted 5.14.0-rc5-syzkaller #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+0x1ae/0x29f lib/dump_stack.c:105
 nmi_cpu_backtrace+0x16c/0x190 lib/nmi_backtrace.c:105
 nmi_trigger_cpumask_backtrace+0x191/0x2f0 lib/nmi_backtrace.c:62
 trigger_single_cpu_backtrace include/linux/nmi.h:164 [inline]
 rcu_dump_cpu_stacks+0x22d/0x390 kernel/rcu/tree_stall.h:342
 print_cpu_stall kernel/rcu/tree_stall.h:625 [inline]
 check_cpu_stall kernel/rcu/tree_stall.h:700 [inline]
 rcu_pending kernel/rcu/tree.c:3922 [inline]
 rcu_sched_clock_irq+0x1d0d/0x2a30 kernel/rcu/tree.c:2641
 update_process_times+0x197/0x200 kernel/time/timer.c:1785
 tick_sched_handle kernel/time/tick-sched.c:226 [inline]
 tick_sched_timer+0x27d/0x420 kernel/time/tick-sched.c:1421
 __run_hrtimer kernel/time/hrtimer.c:1537 [inline]
 __hrtimer_run_queues+0x4cb/0xa60 kernel/time/hrtimer.c:1601
 hrtimer_interrupt+0x3b3/0x1040 kernel/time/hrtimer.c:1663
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1089 [inline]
 __sysvec_apic_timer_interrupt+0xf9/0x270 arch/x86/kernel/apic/apic.c:1106
 sysvec_apic_timer_interrupt+0x8c/0xb0 arch/x86/kernel/apic/apic.c:1100
 </IRQ>
 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:638
RIP: 0010:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:161 [inline]
RIP: 0010:_raw_spin_unlock_irqrestore+0xbc/0x120 kernel/locking/spinlock.c:191
Code: f0 48 c1 e8 03 42 80 3c 20 00 74 08 4c 89 f7 e8 1a 60 ed f7 f6 44 24 21 02 75 4e 41 f7 c7 00 02 00 00 74 01 fb bf 01 00 00 00 <e8> 4f 77 7b f7 65 8b 05 b0 cd 25 76 85 c0 74 3f 48 c7 04 24 0e 36
RSP: 0018:ffffc90000d276a0 EFLAGS: 00000206
RAX: 1ffff920001a4ed8 RBX: ffff888146c80000 RCX: ffffffff8162c8d9
RDX: dffffc0000000000 RSI: 0000000000000101 RDI: 0000000000000001
RBP: ffffc90000d27730 R08: dffffc0000000000 R09: fffffbfff1f5e7d9
R10: fffffbfff1f5e7d9 R11: 0000000000000000 R12: dffffc0000000000
R13: 1ffff920001a4ed4 R14: ffffc90000d276c0 R15: 0000000000000a06
 dummy_timer+0x2fff/0x30f0 drivers/usb/gadget/udc/dummy_hcd.c:1996
 call_timer_fn+0xf6/0x210 kernel/time/timer.c:1421
 expire_timers kernel/time/timer.c:1466 [inline]
 __run_timers+0x703/0x8f0 kernel/time/timer.c:1734
 run_timer_softirq+0x63/0xf0 kernel/time/timer.c:1747
 __do_softirq+0x372/0x783 kernel/softirq.c:558
 run_ksoftirqd+0xa2/0x100 kernel/softirq.c:920
 smpboot_thread_fn+0x533/0x9d0 kernel/smpboot.c:164
 kthread+0x453/0x480 kernel/kthread.c:319
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
----------------
Code disassembly (best guess):
   0:	f0 48 c1 e8 03       	lock shr $0x3,%rax
   5:	42 80 3c 20 00       	cmpb   $0x0,(%rax,%r12,1)
   a:	74 08                	je     0x14
   c:	4c 89 f7             	mov    %r14,%rdi
   f:	e8 1a 60 ed f7       	callq  0xf7ed602e
  14:	f6 44 24 21 02       	testb  $0x2,0x21(%rsp)
  19:	75 4e                	jne    0x69
  1b:	41 f7 c7 00 02 00 00 	test   $0x200,%r15d
  22:	74 01                	je     0x25
  24:	fb                   	sti    
  25:	bf 01 00 00 00       	mov    $0x1,%edi
  2a:	e8 4f 77 7b f7       	callq  0xf77b777e <-- trapping instruction
  2f:	65 8b 05 b0 cd 25 76 	mov    %gs:0x7625cdb0(%rip),%eax        # 0x7625cde6
  36:	85 c0                	test   %eax,%eax
  38:	74 3f                	je     0x79
  3a:	48                   	rex.W
  3b:	c7                   	.byte 0xc7
  3c:	04 24                	add    $0x24,%al
  3e:	0e                   	(bad)  
  3f:	36                   	ss