syzbot

IPv6: ADDRCONF(NETDEV_CHANGE): hsr_slave_1: link becomes ready
IPv6: ADDRCONF(NETDEV_CHANGE): hsr0: link becomes ready
IPv6: ADDRCONF(NETDEV_UP): vxcan1: link is not ready
8021q: adding VLAN 0 to HW filter on device batadv0
rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 	0-...!: (1 GPs behind) idle=2f2/1/0x4000000000000002 softirq=11041/11042 fqs=18 
rcu: 	 (t=10500 jiffies g=5473 q=104)
rcu: rcu_preempt kthread starved for 10463 jiffies! g5473 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->cpu=1
rcu: RCU grace-period kthread stack dump:
rcu_preempt     I29424    10      2 0x80000000
Call Trace:
 context_switch kernel/sched/core.c:2826 [inline]
 __schedule+0x866/0x1dc0 kernel/sched/core.c:3474
 schedule+0x92/0x1c0 kernel/sched/core.c:3518
 schedule_timeout+0x4db/0xfc0 kernel/time/timer.c:1804
 rcu_gp_kthread+0xd5c/0x2190 kernel/rcu/tree.c:2202
 kthread+0x354/0x420 kernel/kthread.c:246
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415
NMI backtrace for cpu 0
CPU: 0 PID: 7609 Comm: kworker/0:2 Not tainted 4.19.73 #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+0x172/0x1f0 lib/dump_stack.c:113
 nmi_cpu_backtrace.cold+0x63/0xa4 lib/nmi_backtrace.c:101
 nmi_trigger_cpumask_backtrace+0x1b0/0x1f8 lib/nmi_backtrace.c:62
 arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:38
 trigger_single_cpu_backtrace include/linux/nmi.h:164 [inline]
 rcu_dump_cpu_stacks+0x189/0x1d5 kernel/rcu/tree.c:1340
 print_cpu_stall kernel/rcu/tree.c:1478 [inline]
 check_cpu_stall kernel/rcu/tree.c:1550 [inline]
 __rcu_pending kernel/rcu/tree.c:3293 [inline]
 rcu_pending kernel/rcu/tree.c:3336 [inline]
 rcu_check_callbacks.cold+0x5e3/0xd90 kernel/rcu/tree.c:2682
 update_process_times+0x32/0x80 kernel/time/timer.c:1636
 tick_sched_handle+0xa2/0x190 kernel/time/tick-sched.c:164
 tick_sched_timer+0x47/0x130 kernel/time/tick-sched.c:1274
 __run_hrtimer kernel/time/hrtimer.c:1398 [inline]
 __hrtimer_run_queues+0x33b/0xdc0 kernel/time/hrtimer.c:1460
 hrtimer_interrupt+0x314/0x770 kernel/time/hrtimer.c:1518
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1067 [inline]
 smp_apic_timer_interrupt+0x111/0x550 arch/x86/kernel/apic/apic.c:1092
 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:893
 </IRQ>
RIP: 0010:__sanitizer_cov_trace_pc+0x26/0x50 kernel/kcov.c:101
Code: 90 90 90 90 55 48 89 e5 48 8b 75 08 65 48 8b 04 25 40 ee 01 00 65 8b 15 18 8b 96 7e 81 e2 00 01 1f 00 75 2b 8b 90 d0 12 00 00 <83> fa 02 75 20 48 8b 88 d8 12 00 00 8b 80 d4 12 00 00 48 8b 11 48
RSP: 0018:ffff888091d97438 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13
RAX: ffff8880a41ea200 RBX: ffff8880a542b4f8 RCX: ffffffff858ebde6
RDX: 0000000000000000 RSI: ffffffff858ebdf0 RDI: 0000000000000001
RBP: ffff888091d97438 R08: ffff8880a41ea200 R09: 0000000000000007
R10: ffff8880a41eab98 R11: 000000005c47cd25 R12: dffffc0000000000
R13: ffff8880a542b240 R14: 0000000000000001 R15: 0000000000000000
 __list_del_entry include/linux/list.h:120 [inline]
 __list_del_entry include/linux/list.h:115 [inline]
 list_move_tail include/linux/list.h:182 [inline]
 hhf_dequeue+0x5c0/0xa00 net/sched/sch_hhf.c:438
 dequeue_skb net/sched/sch_generic.c:277 [inline]
 qdisc_restart net/sched/sch_generic.c:380 [inline]
 __qdisc_run+0x1e7/0x1960 net/sched/sch_generic.c:398
 __dev_xmit_skb net/core/dev.c:3501 [inline]
 __dev_queue_xmit+0x165c/0x2fe0 net/core/dev.c:3811
 dev_queue_xmit+0x18/0x20 net/core/dev.c:3876
 neigh_resolve_output net/core/neighbour.c:1369 [inline]
 neigh_resolve_output+0x5b7/0x980 net/core/neighbour.c:1349
 neigh_output include/net/neighbour.h:501 [inline]
 ip6_finish_output2+0xb7f/0x2550 net/ipv6/ip6_output.c:120
 ip6_finish_output+0x574/0xbe0 net/ipv6/ip6_output.c:154
 NF_HOOK_COND include/linux/netfilter.h:278 [inline]
 ip6_output+0x235/0x7c0 net/ipv6/ip6_output.c:171
 dst_output include/net/dst.h:447 [inline]
 NF_HOOK include/linux/netfilter.h:289 [inline]
 ndisc_send_skb+0xf3b/0x1460 net/ipv6/ndisc.c:491
 ndisc_send_ns+0x3a9/0x850 net/ipv6/ndisc.c:633
 addrconf_dad_work+0xb88/0x1150 net/ipv6/addrconf.c:4062
 process_one_work+0x989/0x1750 kernel/workqueue.c:2153
 worker_thread+0x98/0xe40 kernel/workqueue.c:2296
 kthread+0x354/0x420 kernel/kthread.c:246
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415