rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 	1-...!: (10500 ticks this GP) idle=3804/1/0x4000000000000000 softirq=36365/36365 fqs=0
rcu: 	(t=10500 jiffies g=33125 q=868 ncpus=2)
rcu: rcu_preempt kthread timer wakeup didn't happen for 10499 jiffies! g33125 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402
rcu: 	Possible timer handling issue on cpu=1 timer-softirq=13916
rcu: rcu_preempt kthread starved for 10500 jiffies! g33125 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->cpu=1
rcu: 	Unless rcu_preempt kthread gets sufficient CPU time, OOM is now expected behavior.
rcu: RCU grace-period kthread stack dump:
task:rcu_preempt     state:I stack:27160 pid:16    tgid:16    ppid:2      task_flags:0x208040 flags:0x00004000
Call Trace:
 <TASK>
 __schedule+0x1798/0x4cc0
 schedule+0x165/0x360
 schedule_timeout+0x12b/0x270
 rcu_gp_fqs_loop+0x301/0x1540
 rcu_gp_kthread+0x99/0x390
 kthread+0x711/0x8a0
 ret_from_fork+0x439/0x7d0
 ret_from_fork_asm+0x1a/0x30
 </TASK>
CPU: 1 UID: 0 PID: 1365 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:_raw_spin_unlock_irqrestore+0xa8/0x110
Code: 74 05 e8 2b 78 4a f6 48 c7 44 24 20 00 00 00 00 9c 8f 44 24 20 f6 44 24 21 02 75 4f f7 c3 00 02 00 00 74 01 fb bf 01 00 00 00 <e8> e3 1e 13 f6 65 8b 05 6c c1 23 07 85 c0 74 40 48 c7 04 24 0e 36
RSP: 0018:ffffc90007c77680 EFLAGS: 00000206
RAX: 58a282c978d6c100 RBX: 0000000000000a02 RCX: 58a282c978d6c100
RDX: 0000000000000002 RSI: ffffffff8d9b9e62 RDI: 0000000000000001
RBP: ffffc90007c77708 R08: ffffffff8fa3a537 R09: 1ffffffff1f474a6
R10: dffffc0000000000 R11: fffffbfff1f474a7 R12: dffffc0000000000
R13: dffffc0000000000 R14: ffffffff99df5f40 R15: 1ffff92000f8eed0
FS:  0000000000000000(0000) GS:ffff8881a3c15000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007efeb7e0afc8 CR3: 000000000df36000 CR4: 00000000000006f0
Call Trace:
 <TASK>
 uart_port_unlock_deref+0x111/0x2f0
 uart_write_room+0xe4/0x170
 handle_tx+0x163/0x610
 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>
