syzbot

rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 	1-...!: (1 GPs behind) idle=662/1/0x4000000000000002 softirq=287581/287582 fqs=12 
rcu: 	 (t=10500 jiffies g=386245 q=303)
NMI backtrace for cpu 1
CPU: 1 PID: 8890 Comm: syz-executor.4 Not tainted 4.19.134-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+0x1fc/0x2fe lib/dump_stack.c:118
 nmi_cpu_backtrace.cold+0x63/0xa2 lib/nmi_backtrace.c:101
 nmi_trigger_cpumask_backtrace+0x1a6/0x1eb lib/nmi_backtrace.c:62
 trigger_single_cpu_backtrace include/linux/nmi.h:164 [inline]
 rcu_dump_cpu_stacks+0x15f/0x19c 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+0x62d/0xe19 kernel/rcu/tree.c:2682
 update_process_times+0x2a/0x70 kernel/time/timer.c:1649
 tick_sched_handle+0x9b/0x180 kernel/time/tick-sched.c:168
 tick_sched_timer+0xfc/0x290 kernel/time/tick-sched.c:1278
 __run_hrtimer kernel/time/hrtimer.c:1401 [inline]
 __hrtimer_run_queues+0x3f6/0xe60 kernel/time/hrtimer.c:1463
 hrtimer_interrupt+0x32a/0x930 kernel/time/hrtimer.c:1521
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1067 [inline]
 smp_apic_timer_interrupt+0x10c/0x550 arch/x86/kernel/apic/apic.c:1092
 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:894
RIP: 0010:preempt_count_sub+0x7/0x150 kernel/sched/core.c:3257
Code: c8 48 8b 55 d0 e9 eb fb ff ff 89 4d d0 e8 e1 2b 58 00 8b 4d d0 e9 64 fe ff ff 66 0f 1f 84 00 00 00 00 00 48 c7 c0 a0 6a 90 8b <53> 89 fb 48 ba 00 00 00 00 00 fc ff df 48 89 c1 83 e0 07 48 c1 e9
RSP: 0018:ffff8880ae707d18 EFLAGS: 00000206 ORIG_RAX: ffffffffffffff13
RAX: ffffffff8b906aa0 RBX: ffff8880ae729bf0 RCX: 000000006d400000
RDX: 000000006d44a183 RSI: ffffffff835cb3e0 RDI: 0000000000000001
RBP: 0000000000000014 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000005 R11: 0000000000000000 R12: 0000000043b0067d
R13: 1ffff11015ce0fae R14: 0000000000000000 R15: 0000000000000000
 prandom_u32+0x60/0xb0 lib/random32.c:85
 garp_join_timer_arm+0x21/0x80 net/802/garp.c:400
 call_timer_fn+0x177/0x700 kernel/time/timer.c:1337
 expire_timers+0x243/0x4e0 kernel/time/timer.c:1374
 __run_timers kernel/time/timer.c:1695 [inline]
 run_timer_softirq+0x21c/0x670 kernel/time/timer.c:1708
 __do_softirq+0x26c/0x9a0 kernel/softirq.c:292
 do_softirq_own_stack+0x2a/0x40 arch/x86/entry/entry_64.S:1092
 </IRQ>
 do_softirq.part.0+0x160/0x1c0 kernel/softirq.c:336
 do_softirq kernel/softirq.c:328 [inline]
 __local_bh_enable_ip+0x20e/0x270 kernel/softirq.c:189
 local_bh_enable include/linux/bottom_half.h:32 [inline]
 rcu_read_unlock_bh include/linux/rcupdate.h:721 [inline]
 __dev_queue_xmit+0x1628/0x2e00 net/core/dev.c:3865
 pppoe_sendmsg+0x5a9/0x710 drivers/net/ppp/pppoe.c:907
 sock_sendmsg_nosec net/socket.c:622 [inline]
 sock_sendmsg+0xc3/0x120 net/socket.c:632
 ___sys_sendmsg+0x3b3/0x8e0 net/socket.c:2115
 __sys_sendmmsg+0x195/0x470 net/socket.c:2210
 __do_sys_sendmmsg net/socket.c:2239 [inline]
 __se_sys_sendmmsg net/socket.c:2236 [inline]
 __x64_sys_sendmmsg+0x99/0x100 net/socket.c:2236
 do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x45c369
Code: 8d 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 5b b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f60376a2c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000133
RAX: ffffffffffffffda RBX: 0000000000026280 RCX: 000000000045c369
RDX: 040000000000014d RSI: 0000000020005b40 RDI: 0000000000000004
RBP: 000000000078bf48 R08: 0000000000000000 R09: 0000000000000000
R10: 000000000000014c R11: 0000000000000246 R12: 000000000078bf0c
R13: 00007ffec1aad84f R14: 00007f60376a39c0 R15: 000000000078bf0c