I know that -next tree is doing these things daily: 1. reset HEAD to HEAD of linus's tree 2. merge about 221 subsytem trees automatically And I know that -mm tree : 1. contains patches which are going to applied into latest Linus release (3.x or 3.x-rcY) 2. most of the patches are included in -next (this is the original purpose of the -next tree - to reduce Andres Mortan's stress and make the patches more tested) So here comes my questions: I found that most of the -mm patches are in -next, which means they will be tested more by all developers , but there are still some patches are not included in -next tree. So why are they special and how they make their way into Linus 's mainline code ? -- Regards, Zhan Jianyu