diff options
Diffstat (limited to 'kernel/cgroup.c')
| -rw-r--r-- | kernel/cgroup.c | 28 |
1 files changed, 20 insertions, 8 deletions
diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 37c7ab9d3019..3e738a93ed62 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -2541,6 +2541,20 @@ out_release_tset: } /** + * cgroup_may_migrate_to - verify whether a cgroup can be migration destination + * @dst_cgrp: destination cgroup to test + * + * On the default hierarchy, except for the root, subtree_control must be + * zero for migration destination cgroups with tasks so that child cgroups + * don't compete against tasks. + */ +static bool cgroup_may_migrate_to(struct cgroup *dst_cgrp) +{ + return !cgroup_on_dfl(dst_cgrp) || !cgroup_parent(dst_cgrp) || + !dst_cgrp->subtree_control; +} + +/** * cgroup_migrate_finish - cleanup after attach * @preloaded_csets: list of preloaded css_sets * @@ -2634,14 +2648,6 @@ static int cgroup_migrate_prepare_dst(struct cgroup *dst_cgrp, lockdep_assert_held(&cgroup_mutex); - /* - * Except for the root, subtree_control must be zero for a cgroup - * with tasks so that child cgroups don't compete against tasks. - */ - if (dst_cgrp && cgroup_on_dfl(dst_cgrp) && cgroup_parent(dst_cgrp) && - dst_cgrp->subtree_control) - return -EBUSY; - /* look up the dst cset for each src cset and link it to src */ list_for_each_entry_safe(src_cset, tmp_cset, preloaded_csets, mg_preload_node) { struct css_set *dst_cset; @@ -2739,6 +2745,9 @@ static int cgroup_attach_task(struct cgroup *dst_cgrp, struct task_struct *task; int ret; + if (!cgroup_may_migrate_to(dst_cgrp)) + return -EBUSY; + /* look up all src csets */ spin_lock_irq(&css_set_lock); rcu_read_lock(); @@ -4252,6 +4261,9 @@ int cgroup_transfer_tasks(struct cgroup *to, struct cgroup *from) struct task_struct *task; int ret; + if (!cgroup_may_migrate_to(to)) + return -EBUSY; + mutex_lock(&cgroup_mutex); percpu_down_write(&cgroup_threadgroup_rwsem); |