rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 	1-....: (1 GPs behind) idle=c4dc/1/0x4000000000000000 softirq=23696/23697 fqs=5242
rcu: 	         hardirqs   softirqs   csw/system
rcu: 	 number:     5265          0            0
rcu: 	cputime:      318          0        52181   ==> 52510(ms)
rcu: 	(t=10502 jiffies g=18505 q=20077 ncpus=2)
CPU: 1 UID: 0 PID: 1364 Comm: aoe_tx0 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:uart_write+0x4/0x130
Code: e8 51 36 d6 fc eb ce 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 <55> 41 57 41 56 41 55 41 54 53 48 83 ec 10 48 89 d3 49 89 f6 49 89
RSP: 0018:ffffc90007cd7790 EFLAGS: 00000246
RAX: 1ffff11020b4c47b RBX: 0000000000000001 RCX: ffff888109639cc0
RDX: 0000000000000001 RSI: ffff88811269ceb0 RDI: ffff88803afa6000
RBP: ffff888105a623d8 R08: ffff8881069d0f87 R09: 1ffff11020d3a1f0
R10: dffffc0000000000 R11: ffffffff854cf9a0 R12: ffffffff854cf9a0
R13: dffffc0000000000 R14: ffff888105a62300 R15: ffff88803c6f0e08
FS:  0000000000000000(0000) GS:ffff8881a3c15000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f95ccfbd000 CR3: 0000000028a90000 CR4: 00000000000006f0
Call Trace:
 <TASK>
 handle_tx+0x23f/0x610
 dev_hard_start_xmit+0x2d7/0x830
 __dev_queue_xmit+0x1b8d/0x3b50
 tx+0x6b/0x190
 kthread+0x1d0/0x3e0
 kthread+0x711/0x8a0
 ret_from_fork+0x439/0x7d0
 ret_from_fork_asm+0x1a/0x30
 </TASK>
