diff options
| -rw-r--r-- | include/linux/cgroup.h | 8 | ||||
| -rw-r--r-- | kernel/cgroup.c | 56 |
2 files changed, 43 insertions, 21 deletions
diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h index 8c283a910b91..528e2aed36c3 100644 --- a/include/linux/cgroup.h +++ b/include/linux/cgroup.h @@ -324,10 +324,14 @@ struct css_set { struct hlist_node hlist; /* - * List running through all tasks using this cgroup - * group. Protected by css_set_lock + * Lists running through all tasks using this cgroup group. + * mg_tasks lists tasks which belong to this cset but are in the + * process of being migrated out or in. Protected by + * css_set_rwsem, but, during migration, once tasks are moved to + * mg_tasks, it can be read safely while holding cgroup_mutex. */ struct list_head tasks; + struct list_head mg_tasks; /* * List of cgrp_cset_links pointing at cgroups referenced from this diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 8ab800c7bac0..b80c611ff836 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -644,6 +644,7 @@ static struct css_set *find_css_set(struct css_set *old_cset, atomic_set(&cset->refcount, 1); INIT_LIST_HEAD(&cset->cgrp_links); INIT_LIST_HEAD(&cset->tasks); + INIT_LIST_HEAD(&cset->mg_tasks); INIT_HLIST_NODE(&cset->hlist); /* Copy the set of subsystem state objects generated in @@ -2590,9 +2591,14 @@ static void css_advance_task_iter(struct css_task_iter *it) } link = list_entry(l, struct cgrp_cset_link, cset_link); cset = link->cset; - } while (list_empty(&cset->tasks)); + } while (list_empty(&cset->tasks) && list_empty(&cset->mg_tasks)); + it->cset_link = l; - it->task = cset->tasks.next; + + if (!list_empty(&cset->tasks)) + it->task = cset->tasks.next; + else + it->task = cset->mg_tasks.next; } /** @@ -2636,24 +2642,29 @@ struct task_struct *css_task_iter_next(struct css_task_iter *it) { struct task_struct *res; struct list_head *l = it->task; - struct cgrp_cset_link *link; + struct cgrp_cset_link *link = list_entry(it->cset_link, + struct cgrp_cset_link, cset_link); /* If the iterator cg is NULL, we have no tasks */ if (!it->cset_link) return NULL; res = list_entry(l, struct task_struct, cg_list); - /* Advance iterator to find next entry */ + + /* + * Advance iterator to find next entry. cset->tasks is consumed + * first and then ->mg_tasks. After ->mg_tasks, we move onto the + * next cset. + */ l = l->next; - link = list_entry(it->cset_link, struct cgrp_cset_link, cset_link); - if (l == &link->cset->tasks) { - /* - * We reached the end of this task list - move on to the - * next cgrp_cset_link. - */ + + if (l == &link->cset->tasks) + l = link->cset->mg_tasks.next; + + if (l == &link->cset->mg_tasks) css_advance_task_iter(it); - } else { + else it->task = l; - } + return res; } @@ -4502,16 +4513,23 @@ static int cgroup_css_links_read(struct seq_file *seq, void *v) struct css_set *cset = link->cset; struct task_struct *task; int count = 0; + seq_printf(seq, "css_set %p\n", cset); + list_for_each_entry(task, &cset->tasks, cg_list) { - if (count++ > MAX_TASKS_SHOWN_PER_CSS) { - seq_puts(seq, " ...\n"); - break; - } else { - seq_printf(seq, " task %d\n", - task_pid_vnr(task)); - } + if (count++ > MAX_TASKS_SHOWN_PER_CSS) + goto overflow; + seq_printf(seq, " task %d\n", task_pid_vnr(task)); + } + + list_for_each_entry(task, &cset->mg_tasks, cg_list) { + if (count++ > MAX_TASKS_SHOWN_PER_CSS) + goto overflow; + seq_printf(seq, " task %d\n", task_pid_vnr(task)); } + continue; + overflow: + seq_puts(seq, " ...\n"); } up_read(&css_set_rwsem); return 0; |