diff options
| -rw-r--r-- | include/linux/cgroup-defs.h | 3 | ||||
| -rw-r--r-- | kernel/cgroup.c | 20 |
2 files changed, 21 insertions, 2 deletions
diff --git a/include/linux/cgroup-defs.h b/include/linux/cgroup-defs.h index 34b42f03fcd8..3e39ae5bc799 100644 --- a/include/linux/cgroup-defs.h +++ b/include/linux/cgroup-defs.h @@ -212,6 +212,9 @@ struct css_set { /* all css_task_iters currently walking this cset */ struct list_head task_iters; + /* dead and being drained, ignore for migration */ + bool dead; + /* For RCU-protected deletion */ struct rcu_head rcu_head; }; diff --git a/kernel/cgroup.c b/kernel/cgroup.c index e22df5d81e59..d57318950076 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -2516,6 +2516,14 @@ static void cgroup_migrate_add_src(struct css_set *src_cset, lockdep_assert_held(&cgroup_mutex); lockdep_assert_held(&css_set_lock); + /* + * If ->dead, @src_set is associated with one or more dead cgroups + * and doesn't contain any migratable tasks. Ignore it early so + * that the rest of migration path doesn't get confused by it. + */ + if (src_cset->dead) + return; + src_cgrp = cset_cgroup_from_root(src_cset, dst_cgrp->root); if (!list_empty(&src_cset->mg_preload_node)) @@ -5258,6 +5266,7 @@ static int cgroup_destroy_locked(struct cgroup *cgrp) __releases(&cgroup_mutex) __acquires(&cgroup_mutex) { struct cgroup_subsys_state *css; + struct cgrp_cset_link *link; int ssid; lockdep_assert_held(&cgroup_mutex); @@ -5278,11 +5287,18 @@ static int cgroup_destroy_locked(struct cgroup *cgrp) return -EBUSY; /* - * Mark @cgrp dead. This prevents further task migration and child - * creation by disabling cgroup_lock_live_group(). + * Mark @cgrp and the associated csets dead. The former prevents + * further task migration and child creation by disabling + * cgroup_lock_live_group(). The latter makes the csets ignored by + * the migration path. */ cgrp->self.flags &= ~CSS_ONLINE; + spin_lock_bh(&css_set_lock); + list_for_each_entry(link, &cgrp->cset_links, cset_link) + link->cset->dead = true; + spin_unlock_bh(&css_set_lock); + /* initiate massacre of all css's */ for_each_css(css, ssid, cgrp) kill_css(css); |