Hello, On Fri, May 29, 2015 at 03:45:53PM +0200, Michal Hocko wrote: > Sure but we are talking about processes here. They just happen to share > mm. And this is exactly the behavior change I am talking about... With Are we talking about CLONE_VM w/o CLONE_THREAD? ie. two threadgroups sharing the same VM? > the owner you could emulate "threads" with this patch you cannot > anymore. IMO we shouldn't allow for that but just reading the original > commit message (cf475ad28ac35) which has added mm->owner: > " > It also allows several control groups that are virtually grouped by > mm_struct, to exist independent of the memory controller i.e., without > adding mem_cgroup's for each controller, to mm_struct. > " > suggests it might have been intentional. That being said, I think it was I think he's talking about implmenting different controllers which may want to add their own css pointer in mm_struct now wouldn't need to as the mm is tagged with the owning task from which membership of all controllers can be derived. I don't think that's something we need to worry about. We haven't seen even a suggestion for such a controller and even if that happens we'd be better off adding a separate field for the new controller. > a mistake back at the time and we should move on to a saner model. But I > also believe we should be really vocal when the user visible behavior > changes. If somebody really asks for the previous behavior I would > insist on a _strong_ usecase. I'm a bit lost on what's cleared defined is actually changing. It's not like userland had firm control over mm->owner. It was already a crapshoot, no? Thanks. -- tejun -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>