Tejun Heo <t...@kernel.org> writes: >> This effectively forbids process with mm's shared processes being migrated. >> Although enabling the control file might work. > > So, I don't think we need to support putting tasks which share a mm in > different cgroups. That said, if we're gonna put in that restriction, > I think it should be in cgroup core rather than memcg can_attach. The > only thing we'd need to do is widening what cgroup migration considers > to be a process.
Widening the definition of a process sounds good. The memory control group code would still need a way to forbid these in cgroup v1 mode, when someone uses the task file. Using widening instead of denying should reduce the risk of introducing a regression. The only reason I support the crazy case in my earlier patch is so that we can have this discussion and in case we do cause a regression with this change the previous algorithmic cleanup won't have to be reverted as well. Eric
