rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 	1-...!: (10500 ticks this GP) idle=976/1/0x4000000000000002 softirq=15238/15238 fqs=0 
	(t=10500 jiffies g=10493 q=689)
rcu: rcu_preempt kthread starved for 10500 jiffies! g10493 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->cpu=1
rcu: RCU grace-period kthread stack dump:
rcu_preempt     I29272    10      2 0x80004000
Call Trace:
 context_switch kernel/sched/core.c:3385 [inline]
 __schedule+0x934/0x1f90 kernel/sched/core.c:4081
 schedule+0xdc/0x2b0 kernel/sched/core.c:4155
 schedule_timeout+0x486/0xc50 kernel/time/timer.c:1895
 rcu_gp_fqs_loop kernel/rcu/tree.c:1661 [inline]
 rcu_gp_kthread+0x9b2/0x18d0 kernel/rcu/tree.c:1821
 kthread+0x361/0x430 kernel/kthread.c:255
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352
NMI backtrace for cpu 1
CPU: 1 PID: 16 Comm: ksoftirqd/1 Not tainted 5.5.0-rc2-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:77 [inline]
 dump_stack+0x197/0x210 lib/dump_stack.c:118
 nmi_cpu_backtrace.cold+0x70/0xb2 lib/nmi_backtrace.c:101
 nmi_trigger_cpumask_backtrace+0x23b/0x28b 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+0x183/0x1cf 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.cold+0x509/0xc02 kernel/rcu/tree.c:2271
 update_process_times+0x2d/0x70 kernel/time/timer.c:1726
 tick_sched_handle+0xa2/0x190 kernel/time/tick-sched.c:167
 tick_sched_timer+0x53/0x140 kernel/time/tick-sched.c:1310
 __run_hrtimer kernel/time/hrtimer.c:1517 [inline]
 __hrtimer_run_queues+0x364/0xe40 kernel/time/hrtimer.c:1579
 hrtimer_interrupt+0x314/0x770 kernel/time/hrtimer.c:1641
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1110 [inline]
 smp_apic_timer_interrupt+0x160/0x610 arch/x86/kernel/apic/apic.c:1135
 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:829
 </IRQ>
RIP: 0010:fq_dequeue+0x7a2/0x16a0 net/sched/sch_fq.c:505
Code: 89 e0 48 c1 e8 03 42 80 3c 30 00 0f 85 f6 0b 00 00 4d 89 af d8 02 00 00 49 c7 45 48 00 00 00 00 e9 01 fd ff ff e8 7e 56 30 fb <48> 8b 45 90 48 89 45 d0 48 8b 45 a0 42 80 3c 30 00 0f 85 4f 0c 00
RSP: 0018:ffffc90000d7e968 EFLAGS: 00000206 ORIG_RAX: ffffffffffffff13
RAX: ffff8880a9a44440 RBX: 0000000000000000 RCX: ffffffff8644d3d3
RDX: 0000000000000100 RSI: ffffffff8644d672 RDI: ffff88808ff415c8
RBP: ffffc90000d7e9f0 R08: ffff8880a9a44440 R09: fffffbfff16599ca
R10: fffffbfff16599c9 R11: ffffffff8b2cce4f R12: ffff8880a7fe52d8
R13: 0000000000000000 R14: dffffc0000000000 R15: ffff8880a7fe5000
 dequeue_skb net/sched/sch_generic.c:263 [inline]
 qdisc_restart net/sched/sch_generic.c:366 [inline]
 __qdisc_run+0x1a5/0x1770 net/sched/sch_generic.c:384
 __dev_xmit_skb net/core/dev.c:3677 [inline]
 __dev_queue_xmit+0x163f/0x35c0 net/core/dev.c:3982
 dev_queue_xmit+0x18/0x20 net/core/dev.c:4046
 br_dev_queue_push_xmit+0x3f3/0x5e0 net/bridge/br_forward.c:52
 br_nf_dev_queue_xmit+0x34e/0x14b0 net/bridge/br_netfilter_hooks.c:800
 NF_HOOK include/linux/netfilter.h:307 [inline]
 NF_HOOK include/linux/netfilter.h:301 [inline]
 br_nf_post_routing+0x14e9/0x1d10 net/bridge/br_netfilter_hooks.c:848
 nf_hook_entry_hookfn include/linux/netfilter.h:135 [inline]
 nf_hook_slow+0xbc/0x1e0 net/netfilter/core.c:512
 nf_hook include/linux/netfilter.h:262 [inline]
 NF_HOOK include/linux/netfilter.h:305 [inline]
 br_forward_finish+0x215/0x3f0 net/bridge/br_forward.c:65
 br_nf_hook_thresh+0x2e9/0x370 net/bridge/br_netfilter_hooks.c:1019
 br_nf_forward_finish+0x667/0xa80 net/bridge/br_netfilter_hooks.c:564
 NF_HOOK include/linux/netfilter.h:307 [inline]
 NF_HOOK include/linux/netfilter.h:301 [inline]
 br_nf_forward_ip net/bridge/br_netfilter_hooks.c:634 [inline]
 br_nf_forward_ip+0xc65/0x21d0 net/bridge/br_netfilter_hooks.c:575
 nf_hook_entry_hookfn include/linux/netfilter.h:135 [inline]
 nf_hook_slow+0xbc/0x1e0 net/netfilter/core.c:512
 nf_hook include/linux/netfilter.h:262 [inline]
 NF_HOOK include/linux/netfilter.h:305 [inline]
 __br_forward+0x393/0xaf0 net/bridge/br_forward.c:109
 deliver_clone+0x61/0xc0 net/bridge/br_forward.c:125
 br_flood+0x325/0x3d0 net/bridge/br_forward.c:232
 br_handle_frame_finish+0xb46/0x1670 net/bridge/br_input.c:162
 br_nf_hook_thresh+0x2e9/0x370 net/bridge/br_netfilter_hooks.c:1019
 br_nf_pre_routing_finish_ipv6+0x6fa/0xdb0 net/bridge/br_netfilter_ipv6.c:206
 NF_HOOK include/linux/netfilter.h:307 [inline]
 br_nf_pre_routing_ipv6+0x456/0x830 net/bridge/br_netfilter_ipv6.c:236
 br_nf_pre_routing+0x1896/0x22b3 net/bridge/br_netfilter_hooks.c:505
 nf_hook_entry_hookfn include/linux/netfilter.h:135 [inline]
 nf_hook_bridge_pre net/bridge/br_input.c:224 [inline]
 br_handle_frame+0x806/0x1340 net/bridge/br_input.c:349
 __netif_receive_skb_core+0xfbc/0x30b0 net/core/dev.c:5051
 __netif_receive_skb_one_core+0xa8/0x1a0 net/core/dev.c:5148
 __netif_receive_skb+0x2c/0x1d0 net/core/dev.c:5264
 process_backlog+0x206/0x750 net/core/dev.c:6095
 napi_poll net/core/dev.c:6532 [inline]
 net_rx_action+0x508/0x1120 net/core/dev.c:6600
 __do_softirq+0x262/0x98c kernel/softirq.c:292
 run_ksoftirqd kernel/softirq.c:603 [inline]
 run_ksoftirqd+0x8e/0x110 kernel/softirq.c:595
 smpboot_thread_fn+0x6a3/0xa40 kernel/smpboot.c:165
 kthread+0x361/0x430 kernel/kthread.c:255
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352