Linux futex_wait bug

The linux futex_wait call has been broken for about a year (in upstream since 3.14, around Jan 2014), and has just recently been fixed (in upstream 3.18, around October 2014). More importantly this breakage seems to have been back ported into major distros (e.g. into RHEL 6.6 and its cousins, released in October 2014), and the fix for it has only recently been back ported (e.g. RHEL 6.6.z and cousins have the fix).

The impact of this kernel bug is very simple: user processes can deadlock and hang in seemingly impossible situations.

https://groups.google.com/forum/#!topic/mechanical-sympathy/QbmpZxp6C64