rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 	1-....: (10500 ticks this GP) idle=861c/1/0x4000000000000000 softirq=84461/84461 fqs=5249
rcu: 	         hardirqs   softirqs   csw/system
rcu: 	 number:     7291          0            0
rcu: 	cputime:      214          0        52285   ==> 52510(ms)
rcu: 	(t=10502 jiffies g=60397 q=911 ncpus=2)
CPU: 1 UID: 0 PID: 17771 Comm: syz.2.3062 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
RIP: 0010:rcu_read_lock_held+0x0/0x50
Code: 05 21 65 fe 0d e9 50 da d7 09 cc 66 66 66 66 66 66 2e 0f 1f 84 00 00 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 <f3> 0f 1e fa 53 e8 e6 fc d4 09 85 c0 74 26 31 db e8 eb 2d 01 00 84
RSP: 0018:ffffc900069aef08 EFLAGS: 00000202
RAX: ffffffff8984ee52 RBX: 00000000ffff0000 RCX: 0000000000000000
RDX: ffff88801f68d640 RSI: 0000000000000001 RDI: 0000000000000000
RBP: 0000000000000001 R08: ffff88801f68d640 R09: 0000000000000002
R10: 00000000ffffffff R11: 0000000000000000 R12: ffff88802f697838
R13: dffffc0000000000 R14: ffff88802222ec00 R15: ffff888020e28478
FS:  00007f6db77f66c0(0000) GS:ffff8881a3c15000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000006040 CR3: 0000000039c7c000 CR4: 00000000000006f0
Call Trace:
 <TASK>
 qdisc_lookup_rcu+0x32b/0x6d0
 qdisc_tree_reduce_backlog+0x1b2/0x480
 fq_change+0xeba/0x2030
 fq_init+0x699/0x960
 qdisc_create+0x7ac/0xea0
 tc_modify_qdisc+0x1538/0x20e0
 rtnetlink_rcv_msg+0x77c/0xb70
 netlink_rcv_skb+0x208/0x470
 netlink_unicast+0x82f/0x9e0
 netlink_sendmsg+0x805/0xb30
 __sock_sendmsg+0x21c/0x270
 ____sys_sendmsg+0x505/0x830
 ___sys_sendmsg+0x21f/0x2a0
 __x64_sys_sendmsg+0x19b/0x260
 do_syscall_64+0xfa/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f6db958ec29
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 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 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f6db77f6038 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f6db97d5fa0 RCX: 00007f6db958ec29
RDX: 0000000000000000 RSI: 0000200000001200 RDI: 000000000000000f
RBP: 00007f6db9611e41 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f6db97d6038 R14: 00007f6db97d5fa0 R15: 00007ffd491a1af8
 </TASK>
