rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 	1-...!: (1 GPs behind) idle=3ee/1/0x4000000000000002 softirq=12615/12616 fqs=39 
	(t=10500 jiffies g=7141 q=136)
rcu: rcu_preempt kthread starved for 10422 jiffies! g7141 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=0
rcu: RCU grace-period kthread stack dump:
rcu_preempt     R  running task    28984    10      2 0x80004000
Call Trace:
 context_switch kernel/sched/core.c:3385 [inline]
 __schedule+0x9a0/0xcc0 kernel/sched/core.c:4081
 schedule+0x181/0x210 kernel/sched/core.c:4155
 schedule_timeout+0x14f/0x240 kernel/time/timer.c:1895
 rcu_gp_fqs_loop kernel/rcu/tree.c:1661 [inline]
 rcu_gp_kthread+0xed8/0x1770 kernel/rcu/tree.c:1821
 kthread+0x332/0x350 kernel/kthread.c:255
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352
NMI backtrace for cpu 1
CPU: 1 PID: 2679 Comm: kworker/1:2 Not tainted 5.5.0-rc5-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: ipv6_addrconf addrconf_dad_work
Call Trace:
 <IRQ>
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x1fb/0x318 lib/dump_stack.c:118
 nmi_cpu_backtrace+0xaf/0x1a0 lib/nmi_backtrace.c:101
 nmi_trigger_cpumask_backtrace+0x174/0x290 lib/nmi_backtrace.c:62
 arch_trigger_cpumask_backtrace+0x10/0x20 arch/x86/kernel/apic/hw_nmi.c:38
 trigger_single_cpu_backtrace include/linux/nmi.h:164 [inline]
 rcu_dump_cpu_stacks+0x15a/0x220 kernel/rcu/tree_stall.h:254
 print_cpu_stall kernel/rcu/tree_stall.h:455 [inline]
 check_cpu_stall kernel/rcu/tree_stall.h:529 [inline]
 rcu_pending kernel/rcu/tree.c:2827 [inline]
 rcu_sched_clock_irq+0xe25/0x1ad0 kernel/rcu/tree.c:2271
 update_process_times+0x12d/0x180 kernel/time/timer.c:1726
 tick_sched_handle kernel/time/tick-sched.c:167 [inline]
 tick_sched_timer+0x263/0x420 kernel/time/tick-sched.c:1310
 __run_hrtimer kernel/time/hrtimer.c:1517 [inline]
 __hrtimer_run_queues+0x403/0x840 kernel/time/hrtimer.c:1579
 hrtimer_interrupt+0x38c/0xda0 kernel/time/hrtimer.c:1641
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1110 [inline]
 smp_apic_timer_interrupt+0x109/0x280 arch/x86/kernel/apic/apic.c:1135
 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:829
 </IRQ>
RIP: 0010:__memcg_kmem_uncharge+0x1/0x1a0 mm/memcontrol.c:2908
Code: eb 1b 83 3d 20 bf ac 07 00 74 12 48 81 c3 08 02 00 00 48 89 df 4c 89 f6 e8 8c 85 ff ff 5b 41 5e 5d c3 0f 1f 80 00 00 00 00 55 <48> 89 e5 41 57 41 56 41 55 41 54 53 50 89 f3 49 89 fc 48 b8 00 00
RSP: 0018:ffffc90007d1f938 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13
RAX: ffffffff81489244 RBX: ffffea0002904080 RCX: ffff8880a01a0040
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffea0002904080
RBP: ffffc90007d1f980 R08: dffffc0000000000 R09: fffffbfff124248a
R10: fffffbfff124248a R11: 0000000000000000 R12: ffff888095948f20
R13: dffffc0000000000 R14: 1ffff11012b291e4 R15: ffff888097b797f8
 release_task_stack kernel/fork.c:440 [inline]
 put_task_stack+0xa3/0x130 kernel/fork.c:451
 finish_task_switch+0x3f1/0x550 kernel/sched/core.c:3256
 context_switch kernel/sched/core.c:3388 [inline]
 __schedule+0x9a8/0xcc0 kernel/sched/core.c:4081
 preempt_schedule_irq+0xc1/0x140 kernel/sched/core.c:4338
 retint_kernel+0x1b/0x2b
RIP: 0010:refcount_add include/linux/refcount.h:190 [inline]
RIP: 0010:refcount_inc include/linux/refcount.h:228 [inline]
RIP: 0010:in6_dev_hold include/net/addrconf.h:394 [inline]
RIP: 0010:mld_dad_start_timer net/ipv6/mcast.c:1069 [inline]
RIP: 0010:ipv6_mc_dad_complete+0x2a2/0x3b0 net/ipv6/mcast.c:2109
Code: 07 e8 a2 46 70 fa eb 49 4d 8d be a0 01 00 00 4c 89 ff be 04 00 00 00 e8 dc 7c ac fa bb 01 00 00 00 f0 41 0f c1 9e a0 01 00 00 <31> ff 89 de e8 15 4a 70 fa 85 db 74 2f 44 8d 73 01 44 89 f6 09 de
RSP: 0018:ffffc90007d1fb90 EFLAGS: 00000206 ORIG_RAX: ffffffffffffff13
RAX: ffff8880a01a0001 RBX: 0000000000000009 RCX: ffffffff870677f4
RDX: 0000000000000001 RSI: 0000000000000004 RDI: ffff88809bfbc1a0
RBP: ffffc90007d1fbb8 R08: dffffc0000000000 R09: ffffed10137f7835
R10: ffffed10137f7835 R11: 0000000000000000 R12: 0000000000000000
R13: dffffc0000000000 R14: ffff88809bfbc000 R15: ffff88809bfbc1a0
 addrconf_dad_completed+0x73d/0xc70 net/ipv6/addrconf.c:4176
 addrconf_dad_work+0xd3a/0x1c30 net/ipv6/addrconf.c:3962
 process_one_work+0x7ef/0x10d0 kernel/workqueue.c:2264
 worker_thread+0xc01/0x1630 kernel/workqueue.c:2410
 kthread+0x332/0x350 kernel/kthread.c:255
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352