add test for #4811

testsuite/tests/ghc-regress/concurrent/should_run/4811.hs

+import GHC.Conc
+import Control.Concurrent
+import Control.Monad
+
+-- tests for a bug where throwTo targets a thread just created by
+-- forkOnIO, which is still in the process of migrating to another CPU (#4811)
+
+main = do
+  m <- newEmptyMVar
+  forkOnIO 0 $ do
+     replicateM_ 1000 $ do
+       t <- forkOnIO 1 $ return ()
+       killThread t
+     putMVar m ()
+  takeMVar m

testsuite/tests/ghc-regress/concurrent/should_run/all.T

@@ -49,6 +49,7 @@ test('4262', [ skip, # skip for now, it doesn't give reliable results
              compile_and_run, [''])
 
 test('4813', normal, compile_and_run, ['-debug'])
+test('4811', normal, compile_and_run, [''])
 
 # -----------------------------------------------------------------------------
 # These tests we only do for a full run