segfault/assertion failure with multi-threaded profiling

Steps to reproduce:

ghc-stage2 selector_thunks.hs -rtsopts -fforce-recomp -prof -threaded -debug -O2
./selector_thunk +RTS -N4

In a few seconds, it either segfaults or dies with the following error message:

selector_thunks: internal error: ASSERTION FAILED: file rts/dist/build/sm/Evac_thr.c, line 778

    (GHC version 7.7.20131002 for x86_64_unknown_linux)
    Please report this as a GHC bug:  http://www.haskell.org/ghc/reportabug

selector_thunks.hs:

import Control.Monad
import Control.Concurrent
import Data.IORef

main = do
  gref <- newIORef [return ()]
  forM_ [0::Int ..10] $ \_ -> forkIO $ do
    ref <- newIORef [return ()]
    forever $ do
      list <- readIORef gref
      writeIORef ref $! reverse list
      acts <- readIORef ref
      last acts
  forM_ [1..100000099] $ \i ->
    writeIORef gref $! reverse $ 
      concatMap (replicate 10) $
      mapfst $ foldr (\x y -> seq x (x : y)) [] $
      map f [1..10+ (div i 1000000)]

mapfst :: [(a, b)] -> [a]
mapfst [] = []
mapfst (x:xs) = (case x of (a, _) -> a) : mapfst xs

f :: Int -> (IO (), Int)
f x = (x `seq` return (), x)

I only tested the code with a recent HEAD, but I have seen a similar assertion failure with GHC 7.6.3, in a non-contrived application program.

Trac metadata

Trac field	Value
Version	7.7
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Profiling
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