see also version independent topics.

• Meta Ticket #11516

• Status: developing
• release manager: naruse
• ABI Version: 2.3.0

• Declared next version is 2.3
• bump version.h
  • done at r49059, 2014-12-29
• ruby:DevelopersMeeting20150408Japan
• ruby:DevelopersMeeting20150514Japan
• ruby:DevelopersMeeting20150612Japan
• ruby:DevelopersMeeting20150728Japan
• ruby:DevelopersMeeting20150820Japan
• Call for Feature Proposals
  • announce: 2015-08-21 (~09-15)
  • CallForFeatureProposalTemplate
• ruby:DevelopersMeeting20150918Japan
• ruby:DevelopersMeeting20151021Japan
• OedoRubyKaigi 2015-11-08
• ruby:DevelopersMeeting20151109Japan
• preview 1
  • 2015-11-11
  • reviewing features: 1 month
• RubyWorldConference 2015-11-12/13
• RubyConf 2015-11-15/17
• ruby:DevelopersMeeting20151207Japan
• RubyKaigi 2015 2015-12-11/13
• Release Candidate
  • scheduled: 2015-12-11
  • create ruby_2_3 branch
  • don't fix after this unless a critical bug is found
• fix only critical bugs: 2 week
• Release
  • scheduled: 2015-12-25

• without baseruby
• ruby-build
• cross compile

No. Without release manager's explicit permission, you can't backport.