On Wed 31-10-12 12:44:06, Tejun Heo wrote: [...] > diff --git a/kernel/cgroup.c b/kernel/cgroup.c > index f22e3cd..66204a6 100644 > --- a/kernel/cgroup.c > +++ b/kernel/cgroup.c [...] > @@ -4122,13 +4079,30 @@ static int cgroup_rmdir(struct inode *unused_dir, struct dentry *dentry) > } > prepare_to_wait(&cgroup_rmdir_waitq, &wait, TASK_INTERRUPTIBLE); > > - /* block new css_tryget() by deactivating refcnt */ > + /* > + * Block new css_tryget() by deactivating refcnt and mark @cgrp > + * removed. This makes future css_tryget() and child creation > + * attempts fail thus maintaining the removal conditions verified > + * above. > + */ > for_each_subsys(cgrp->root, ss) { > struct cgroup_subsys_state *css = cgrp->subsys[ss->subsys_id]; > > WARN_ON(atomic_read(&css->refcnt) < 0); > atomic_add(CSS_DEACT_BIAS, &css->refcnt); > } > + set_bit(CGRP_REMOVED, &cgrp->flags); > + > + /* > + * Tell subsystems to initate destruction. pre_destroy() should be > + * called with cgroup_mutex unlocked. See 3fa59dfbc3 ("cgroup: fix > + * potential deadlock in pre_destroy") for details. > + */ > + mutex_unlock(&cgroup_mutex); > + for_each_subsys(cgrp->root, ss) > + if (ss->pre_destroy) > + WARN_ON_ONCE(ss->pre_destroy(cgrp)); Do you think that BUG_ON would be too harsh? -- Michal Hocko SUSE Labs -- 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