[GHC] #15544: Non-deterministic segmentation fault in cryptohash-sha256 testsuite

[GHC]

#15544: Non-deterministic segmentation fault in cryptohash-sha256 testsuite
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        Reporter:  bgamari           |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  highest           |            Milestone:  8.6.1
       Component:  Compiler          |              Version:  8.4.3
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by simonmar):

 Aha, yes I think you've found a problem. The run queue is doubly-linked,
 and the `block_info` field of the TSO is used as the back link, but we're
 overwriting that pointer in `unpark_tso`. I'd forgotten about the double
 use of `block_info` when I wrote that patch.

 I don't know if this causes the original problem, there might still be a
 SRT problem, but this queue corruption is definitely a bug. I guess we
 shouldn't touch the `block_info` field here. Would you like to make a
 patch?

 Unfortunately that reintroduces the problem of how to avoid repeated
 wakeup messages.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15544#comment:18>
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