rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 	0-...!: (10500 ticks this GP) idle=614c/1/0x4000000000000000 softirq=80083/80083 fqs=0
rcu: 	(t=10500 jiffies g=58577 q=1 ncpus=1)
rcu: rcu_preempt kthread timer wakeup didn't happen for 10499 jiffies! g58577 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402
rcu: 	Possible timer handling issue on cpu=0 timer-softirq=17118
rcu: rcu_preempt kthread starved for 10500 jiffies! g58577 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->cpu=0
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:27432 pid:16    tgid:16    ppid:2      task_flags:0x208040 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5357 [inline]
 __schedule+0x1798/0x4cc0 kernel/sched/core.c:6961
 __schedule_loop kernel/sched/core.c:7043 [inline]
 schedule+0x165/0x360 kernel/sched/core.c:7058
 schedule_timeout+0x12b/0x270 kernel/time/sleep_timeout.c:99
 rcu_gp_fqs_loop+0x301/0x1540 kernel/rcu/tree.c:2083
 rcu_gp_kthread+0x99/0x390 kernel/rcu/tree.c:2285
 kthread+0x711/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x439/0x7d0 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
CPU: 0 UID: 0 PID: 1315 Comm: aoe_tx0 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
RIP: 0010:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:152 [inline]
RIP: 0010:_raw_spin_unlock_irqrestore+0xa8/0x110 kernel/locking/spinlock.c:194
Code: 74 05 e8 6b 65 48 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> b3 00 11 f6 65 8b 05 6c 81 42 07 85 c0 74 40 48 c7 04 24 0e 36
RSP: 0018:ffffc9000293f680 EFLAGS: 00000206
RAX: 5601f5770b734800 RBX: 0000000000000a02 RCX: 5601f5770b734800
RDX: 0000000000000002 RSI: ffffffff8dbbd263 RDI: 0000000000000001
RBP: ffffc9000293f708 R08: ffffffff8fc3c837 R09: 1ffffffff1f87906
R10: dffffc0000000000 R11: fffffbfff1f87907 R12: dffffc0000000000
R13: dffffc0000000000 R14: ffffffff9a004360 R15: 1ffff92000527ed0
FS:  0000000000000000(0000) GS:ffff88808d007000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f9559afb286 CR3: 0000000054e11000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 spin_unlock_irqrestore include/linux/spinlock.h:406 [inline]
 uart_port_unlock_irqrestore include/linux/serial_core.h:788 [inline]
 uart_port_unlock_deref+0x111/0x2f0 drivers/tty/serial/serial_core.c:91
 uart_write_room+0xe4/0x170 drivers/tty/serial/serial_core.c:650
 handle_tx+0x163/0x610 drivers/net/caif/caif_serial.c:212
 __netdev_start_xmit include/linux/netdevice.h:5222 [inline]
 netdev_start_xmit include/linux/netdevice.h:5231 [inline]
 xmit_one net/core/dev.c:3839 [inline]
 dev_hard_start_xmit+0x2d7/0x830 net/core/dev.c:3855
 __dev_queue_xmit+0x1b8d/0x3b50 net/core/dev.c:4725
 dev_queue_xmit include/linux/netdevice.h:3361 [inline]
 tx+0x6b/0x190 drivers/block/aoe/aoenet.c:62
 kthread+0x1cd/0x3e0 drivers/block/aoe/aoecmd.c:1241
 kthread+0x711/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x439/0x7d0 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>