rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 	0-...!: (10500 ticks this GP) idle=cbe/1/0x4000000000000002 softirq=222988/222988 fqs=0 
	(t=10500 jiffies g=329773 q=2048)
rcu: rcu_preempt kthread starved for 10500 jiffies! g329773 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->cpu=0
rcu: RCU grace-period kthread stack dump:
rcu_preempt     I28944    10      2 0x80004000
Call Trace:
 context_switch kernel/sched/core.c:3384 [inline]
 __schedule+0x94f/0x1e70 kernel/sched/core.c:4069
 schedule+0xd9/0x260 kernel/sched/core.c:4136
 schedule_timeout+0x486/0xc50 kernel/time/timer.c:1895
 rcu_gp_fqs_loop kernel/rcu/tree.c:1639 [inline]
 rcu_gp_kthread+0x9b2/0x18d0 kernel/rcu/tree.c:1799
 kthread+0x361/0x430 kernel/kthread.c:255
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352
NMI backtrace for cpu 0
CPU: 0 PID: 9882 Comm: syz-executor.3 Not tainted 5.4.0-rc5+ #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+0x172/0x1f0 lib/dump_stack.c:113
 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:2795 [inline]
 rcu_sched_clock_irq.cold+0x4fd/0xc12 kernel/rcu/tree.c:2244
 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:1299
 __run_hrtimer kernel/time/hrtimer.c:1514 [inline]
 __hrtimer_run_queues+0x364/0xe40 kernel/time/hrtimer.c:1576
 hrtimer_interrupt+0x314/0x770 kernel/time/hrtimer.c:1638
 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:830
 </IRQ>
RIP: 0010:__read_once_size include/linux/compiler.h:199 [inline]
RIP: 0010:__sanitizer_cov_trace_pc+0x38/0x50 kernel/kcov.c:107
Code: 8b 15 44 dc 8e 7e 81 e2 00 01 1f 00 48 8b 75 08 75 2b 8b 90 f8 12 00 00 83 fa 02 75 20 48 8b 88 00 13 00 00 8b 80 fc 12 00 00 <48> 8b 11 48 83 c2 01 48 39 d0 76 07 48 89 34 d1 48 89 11 5d c3 0f
RSP: 0018:ffff888067b87588 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13
RAX: 0000000000040000 RBX: 0000000000000000 RCX: ffffc90005cef000
RDX: 0000000000000002 RSI: ffffffff85caf503 RDI: 0000000000000005
RBP: ffff888067b87588 R08: ffff8880442fa1c0 R09: fffffbfff14eff4b
R10: fffffbfff14eff4a R11: ffffffff8a77fa57 R12: ffff8880619c7338
R13: ffff8880619c7320 R14: dffffc0000000000 R15: ffff8880619c7320
 cbq_dequeue_prio net/sched/sch_cbq.c:700 [inline]
 cbq_dequeue_1 net/sched/sch_cbq.c:792 [inline]
 cbq_dequeue+0xc33/0x2330 net/sched/sch_cbq.c:816
 dequeue_skb net/sched/sch_generic.c:263 [inline]
 qdisc_restart net/sched/sch_generic.c:366 [inline]
 __qdisc_run+0x1e5/0x1a00 net/sched/sch_generic.c:384
 __dev_xmit_skb net/core/dev.c:3537 [inline]
 __dev_queue_xmit+0x169d/0x3720 net/core/dev.c:3842
 dev_queue_xmit+0x18/0x20 net/core/dev.c:3906
 packet_snd net/packet/af_packet.c:2959 [inline]
 packet_sendmsg+0x2571/0x6140 net/packet/af_packet.c:2984
 sock_sendmsg_nosec net/socket.c:637 [inline]
 sock_sendmsg+0xd7/0x130 net/socket.c:657
 sock_write_iter+0x27c/0x3e0 net/socket.c:989
 call_write_iter include/linux/fs.h:1895 [inline]
 new_sync_write+0x4d3/0x770 fs/read_write.c:483
 __vfs_write+0xe1/0x110 fs/read_write.c:496
 vfs_write+0x268/0x5d0 fs/read_write.c:558
 ksys_write+0x14f/0x290 fs/read_write.c:611
 __do_sys_write fs/read_write.c:623 [inline]
 __se_sys_write fs/read_write.c:620 [inline]
 __x64_sys_write+0x73/0xb0 fs/read_write.c:620
 do_syscall_64+0xfa/0x760 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x459f49
Code: ad b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 7b b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f82881f4c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000459f49
RDX: 000000000000004c RSI: 0000000020000340 RDI: 0000000000000003
RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f82881f56d4
R13: 00000000004ca5b3 R14: 00000000004e2700 R15: 00000000ffffffff