This patchset adds cancellable MCS locks (+dependencies) from 3.15.
More info: http://bit.ly/Xq41R6 / http://lwn.net/Articles/590243/

It will only work on x86/x64_64 thanks to completely unecessary and
unrelated Kconfig changes that I didn't backport. Also 'qrwlocks'
and several other build-related changes were dropped in order to
reduce the chances of conflicts with future -stable patches.