Add a README section about the MRI stuck/crash behavior

README.md

@@ -74,7 +74,7 @@ Install the gem `mutant` via your preferred method.
 gem install mutant
 ```
 
-If you plan to use the RSpec integration you'll have to install `mutant-rspec` also. 
+If you plan to use the RSpec integration you'll have to install `mutant-rspec` also.
 Please add an explicit dependency to `rspec-core` for the RSpec version you want to use.
 
 ```ruby
@@ -83,6 +83,31 @@ gem install mutant-rspec
 
 The minitest integration is still in the works.
 
+The Crash / Stuck Problem (MRI)
+-------------------------------
+
+Mutations generated by mutant can cause MRI to enter VM states its not prepared for.
+All MRI versions above 1.9 are affected by this depending on your compiler flags, compiler version, 
+and OS scheduling behavior.
+
+This can have the following unintended effects:
+
+* MRI crashes with a segfault. Mutant kills each mutation in a dedicated fork to isolate
+  the mutations side effects when this fork terminates abnormally (segfault) mutant
+  counts the mutation as killed.
+
+* MRI crashes with a segfault and gets stuck when handling the segfault.
+  Depending on the number of active kill jobs mutant might appear to continue normally untill
+  all workers are stuck into this state when it begins to hang.
+  Currently mutant must assume that your test suite simply not terminated yet as from the outside
+  (parent process) the difference between a long running test and a stuck MRI is not observable.
+  Its planned to implement a timeout enforced from the parent process, but ideally MRI simply gets fixed.
+
+References:
+
+* Mutant bug: https://github.com/mbj/mutant/issues/265
+* Upstream bug: https://bugs.ruby-lang.org/issues/10460
+
 Examples
 --------