On Thu, 25 Jan 2018, Andrew Morton wrote: > > Now that each mem cgroup on the system has a memory.oom_policy tunable to > > specify oom kill selection behavior, remove the needless "groupoom" mount > > option that requires (1) the entire system to be forced, perhaps > > unnecessarily, perhaps unexpectedly, into a single oom policy that > > differs from the traditional per process selection, and (2) a remount to > > change. > > > > Instead of enabling the cgroup aware oom killer with the "groupoom" mount > > option, set the mem cgroup subtree's memory.oom_policy to "cgroup". > > Can we retain the groupoom mount option and use its setting to set the > initial value of every memory.oom_policy? That way the mount option > remains somewhat useful and we're back-compatible? > -ECONFUSED. We want to have a mount option that has the sole purpose of doing echo cgroup > /mnt/cgroup/memory.oom_policy? Please note that this patchset is not only to remove a mount option, it is to allow oom policies to be configured per subtree such that users whom you delegate those subtrees to cannot evade the oom policy that is set at a higher level. The goal is to prevent the user from needing to organize their hierarchy is a specific way to work around this constraint and use things like limiting the number of child cgroups that user is allowed to create only to work around the oom policy. With a cgroup v2 single hierarchy it severely limits the amount of control the user has over their processes because they are locked into a very specific hierarchy configuration solely to not allow the user to evade oom kill. This, and fixes to fairly compare the root mem cgroup with leaf mem cgroups, are essential before the feature is merged otherwise it yields wildly unpredictable (and unexpected, since its interaction with oom_score_adj isn't documented) results as I already demonstrated where cgroups with 1GB of usage are killed instead of 6GB workers outside of that subtree. -- To unsubscribe from this list: send the line "unsubscribe cgroups" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
