rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 	1-....: (1 GPs behind) idle=699c/1/0x4000000000000000 softirq=999055/999094 fqs=5232
rcu: 	         hardirqs   softirqs   csw/system
rcu: 	 number:     6104          0            0
rcu: 	cputime:      253          0        52235   ==> 52490(ms)
rcu: 	(t=10500 jiffies g=379973 q=2836 ncpus=2)
CPU: 1 UID: 0 PID: 13972 Comm: syz.0.8472 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:qdisc_tree_reduce_backlog+0x2cf/0x480
Code: f8 48 c1 e8 03 0f b6 04 28 84 c0 0f 85 b6 00 00 00 8b 44 24 08 41 29 87 e8 00 00 00 49 8d bd 44 01 00 00 48 89 f8 48 c1 e8 03 <0f> b6 04 28 84 c0 0f 85 ab 00 00 00 8b 44 24 0c 41 29 87 44 01 00
RSP: 0018:ffffc90007e36f48 EFLAGS: 00000a07
RAX: 1ffff11020a76228 RBX: 1ffffffff193035c RCX: 0000000000080000
RDX: ffffc90009219000 RSI: 000000000007ffff RDI: ffff8881053b1144
RBP: dffffc0000000000 R08: ffff88801fbd8000 R09: 0000000000000002
R10: 00000000ffffffff R11: 0000000000000002 R12: 00000000fffffff1
R13: ffff8881053b1000 R14: dffffc0000000000 R15: ffff8881053b1000
FS:  00007f1807b826c0(0000) GS:ffff8881a3c13000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f728a5f6d58 CR3: 0000000113368000 CR4: 00000000000006f0
Call Trace:
 <TASK>
 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: 0033:0x7f1806d8ec29
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:00007f1807b82038 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f1806fd6090 RCX: 00007f1806d8ec29
RDX: 0000000000000000 RSI: 0000200000001200 RDI: 0000000000000007
RBP: 00007f1806e11e41 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f1806fd6128 R14: 00007f1806fd6090 R15: 00007ffe1b37d7d8
 </TASK>
