On Mon 08-04-13 08:57:26, Tejun Heo wrote: > Hello, > > On Mon, Apr 08, 2013 at 04:47:50PM +0200, Michal Hocko wrote: > > On Mon 08-04-13 16:20:11, Li Zefan wrote: > > [...] > > > @@ -5299,6 +5300,26 @@ struct cgroup_subsys_state *cgroup_css_from_dir(struct file *f, int id) > > > return css ? css : ERR_PTR(-ENOENT); > > > } > > > > > > +/** > > > + * cgroup_is_ancestor - test "root" cgroup is an ancestor of "child" > > > + * @child: the cgroup to be tested. > > > + * @root: the cgroup supposed to be an ancestor of the child. > > > + * > > > + * Returns true if "root" is an ancestor of "child" in its hierarchy. > > > + */ > > > +bool cgroup_is_ancestor(struct cgroup *child, struct cgroup *root) > > > +{ > > > + int depth = child->depth; > > > > Is this functionality helpful for other controllers but memcg? > > css_is_ancestor is currently used only by memcg code AFAICS and we can > > get the same functionality easily by using something like: > > It's a basic hierarchy operation. Which nobody seem to need ATM so it could be added later when an user emerges. > I'd prefer it to be in cgroup and in general let's try to avoid > memcg-specific infrastructure. Now that I am thinking about that some more css_is_ancestor is even not correct. Consider this for example root \ A (use_hierarchy = 0) \ B (use_hierarchy = 1) \ C __mem_cgroup_same_or_subtree(A, C) would happily return true even though this is not correct because A is not a part of the same hierarchy. So it seems that memcg will need a special treatment here anyway because cgroup core doesn't know about use_hierarchy thingy which is still with us... I will post a patch. > It doesn't seem to end well. > > Thanks. > > -- > tejun > -- > 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 -- Michal Hocko SUSE Labs -- 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>