rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 	1-...!: (1 GPs behind) idle=21a/1/0x4000000000000002 softirq=11368/11369 fqs=64 
	(t=10500 jiffies g=16645 q=422)
rcu: rcu_preempt kthread starved for 10369 jiffies! g16645 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->cpu=0
rcu: RCU grace-period kthread stack dump:
rcu_preempt     I28848    10      2 0x80004000
Call Trace:
 schedule+0xd0/0x2a0 kernel/sched/core.c:4158
 schedule_timeout+0x35c/0x850 kernel/time/timer.c:1898
 rcu_gp_fqs_loop kernel/rcu/tree.c:1674 [inline]
 rcu_gp_kthread+0x9bf/0x1960 kernel/rcu/tree.c:1836
 kthread+0x388/0x470 kernel/kthread.c:268
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352
NMI backtrace for cpu 1
CPU: 1 PID: 9415 Comm: syz-executor.0 Not tainted 5.7.0-rc4-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+0x188/0x20d lib/dump_stack.c:118
 nmi_cpu_backtrace.cold+0x70/0xb1 lib/nmi_backtrace.c:101
 nmi_trigger_cpumask_backtrace+0x231/0x27e lib/nmi_backtrace.c:62
 trigger_single_cpu_backtrace include/linux/nmi.h:164 [inline]
 rcu_dump_cpu_stacks+0x19b/0x1e5 kernel/rcu/tree_stall.h:254
 print_cpu_stall kernel/rcu/tree_stall.h:475 [inline]
 check_cpu_stall kernel/rcu/tree_stall.h:549 [inline]
 rcu_pending kernel/rcu/tree.c:3225 [inline]
 rcu_sched_clock_irq.cold+0x55d/0xcfa kernel/rcu/tree.c:2296
 update_process_times+0x25/0x60 kernel/time/timer.c:1727
 tick_sched_handle+0x9b/0x180 kernel/time/tick-sched.c:176
 tick_sched_timer+0x4e/0x140 kernel/time/tick-sched.c:1320
 __run_hrtimer kernel/time/hrtimer.c:1520 [inline]
 __hrtimer_run_queues+0x5ca/0xed0 kernel/time/hrtimer.c:1584
 hrtimer_interrupt+0x312/0x770 kernel/time/hrtimer.c:1646
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1113 [inline]
 smp_apic_timer_interrupt+0x15b/0x600 arch/x86/kernel/apic/apic.c:1138
 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:829
 </IRQ>
RIP: 0010:sfq_dequeue+0x1f2/0xcc0 net/sched/sch_sfq.c:494
Code: 4c 89 e8 48 c1 e8 03 42 0f b6 14 30 4c 89 e8 83 e0 07 83 c0 01 38 d0 7c 08 84 d2 0f 85 d6 09 00 00 0f b7 73 1a 31 ff 89 34 24 <e8> 89 af 2c fb 8b 34 24 66 85 f6 0f 8e 2a ff ff ff e8 28 ae 2c fb
RSP: 0018:ffffc90016746f40 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13
RAX: 0000000000000003 RBX: ffff8880538d1bc8 RCX: ffffc90001b19000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffff88809c6f4000 R08: ffff88805237a200 R09: fffff52002ce8dc6
R10: 0000000000000003 R11: fffff52002ce8dc5 R12: 0000000000001bc8
R13: ffff8880538d1be2 R14: dffffc0000000000 R15: 000000000000007f
 dequeue_skb net/sched/sch_generic.c:263 [inline]
 qdisc_restart net/sched/sch_generic.c:366 [inline]
 __qdisc_run+0x1ac/0x17b0 net/sched/sch_generic.c:384
 __dev_xmit_skb net/core/dev.c:3704 [inline]
 __dev_queue_xmit+0x1d07/0x30a0 net/core/dev.c:4021
 neigh_hh_output include/net/neighbour.h:499 [inline]
 neigh_output include/net/neighbour.h:508 [inline]
 ip6_finish_output2+0xfb5/0x25b0 net/ipv6/ip6_output.c:117
 __ip6_finish_output+0x442/0xab0 net/ipv6/ip6_output.c:143
 ip6_finish_output+0x34/0x1f0 net/ipv6/ip6_output.c:153
 NF_HOOK_COND include/linux/netfilter.h:296 [inline]
 ip6_output+0x239/0x810 net/ipv6/ip6_output.c:176
 dst_output include/net/dst.h:435 [inline]
 NF_HOOK include/linux/netfilter.h:307 [inline]
 NF_HOOK include/linux/netfilter.h:301 [inline]
 ip6_xmit+0xe1a/0x2090 net/ipv6/ip6_output.c:280
 inet6_csk_xmit+0x339/0x610 net/ipv6/inet6_connection_sock.c:135
 dccp_transmit_skb+0x968/0x12d0 net/dccp/output.c:138
 dccp_xmit_packet+0x1f1/0x640 net/dccp/output.c:277
 dccp_write_xmit+0x16d/0x1d0 net/dccp/output.c:359
 dccp_sendmsg+0xa64/0xd20 net/dccp/proto.c:812
 inet_sendmsg+0x99/0xe0 net/ipv4/af_inet.c:807
 sock_sendmsg_nosec net/socket.c:652 [inline]
 sock_sendmsg+0xcf/0x120 net/socket.c:672
 ____sys_sendmsg+0x308/0x7e0 net/socket.c:2362
 ___sys_sendmsg+0x100/0x170 net/socket.c:2416
 __sys_sendmmsg+0x296/0x480 net/socket.c:2499
 __compat_sys_sendmmsg net/compat.c:672 [inline]
 __do_compat_sys_sendmmsg net/compat.c:679 [inline]
 __se_compat_sys_sendmmsg net/compat.c:676 [inline]
 __ia32_compat_sys_sendmmsg+0x9b/0x100 net/compat.c:676
 do_syscall_32_irqs_on arch/x86/entry/common.c:337 [inline]
 do_fast_syscall_32+0x270/0xe90 arch/x86/entry/common.c:396
 entry_SYSENTER_compat+0x70/0x7f arch/x86/entry/entry_64_compat.S:139