Trigger read fault deadlock.

test_deadlock.ml

let r1 : int list ref = ref [1024]
let r2 : int list ref = ref [1024]

let rec foo lr fr = function
  | 0 -> foo lr fr 1024
  | i ->
      let v = Random.int i in
      lr := [v];
      foo lr fr @@ List.hd(!fr)

let () = Domain.spawn (fun () -> foo r1 r2 1024)
let () = foo r2 r1 1024