RCU stall in 8250 serial driver Linux 4.15-rc1

[Shankara Pailoor]

Hi,

Syzkaller found the following rcu stall report in Linux 4.15-rc1:
https://pastebin.com/NyZ9JdRv

The following C program reproduces it: https://pastebin.com/gqwDWWpA

Configs Here: https://pastebin.com/v6M3iKi1

Regards,
Shankara