diff --git a/kernel/cgroup.c b/kernel/cgroup.c index f24d3cedd809..f924158a1b65 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -2799,6 +2799,7 @@ static int cgroup_subtree_control_show(struct seq_file *seq, void *v) static int cgroup_update_dfl_csses(struct cgroup *cgrp) { LIST_HEAD(preloaded_csets); + struct cgroup_taskset tset = CGROUP_TASKSET_INIT(tset); struct cgroup_subsys_state *css; struct css_set *src_cset; int ret; @@ -2827,50 +2828,21 @@ static int cgroup_update_dfl_csses(struct cgroup *cgrp) if (ret) goto out_finish; + down_write(&css_set_rwsem); list_for_each_entry(src_cset, &preloaded_csets, mg_preload_node) { - struct task_struct *last_task = NULL, *task; + struct task_struct *task, *ntask; /* src_csets precede dst_csets, break on the first dst_cset */ if (!src_cset->mg_src_cgrp) break; - /* - * All tasks in src_cset need to be migrated to the - * matching dst_cset. Empty it process by process. We - * walk tasks but migrate processes. The leader might even - * belong to a different cset but such src_cset would also - * be among the target src_csets because the default - * hierarchy enforces per-process membership. - */ - while (true) { - down_read(&css_set_rwsem); - task = list_first_entry_or_null(&src_cset->tasks, - struct task_struct, cg_list); - if (task) { - task = task->group_leader; - WARN_ON_ONCE(!task_css_set(task)->mg_src_cgrp); - get_task_struct(task); - } - up_read(&css_set_rwsem); - - if (!task) - break; - - /* guard against possible infinite loop */ - if (WARN(last_task == task, - "cgroup: update_dfl_csses failed to make progress, aborting in inconsistent state\n")) - goto out_finish; - last_task = task; - - ret = cgroup_migrate(task, true, src_cset->dfl_cgrp); - - put_task_struct(task); - - if (WARN(ret, "cgroup: failed to update controllers for the default hierarchy (%d), further operations may crash or hang\n", ret)) - goto out_finish; - } + /* all tasks in src_csets need to be migrated */ + list_for_each_entry_safe(task, ntask, &src_cset->tasks, cg_list) + cgroup_taskset_add(task, &tset); } + up_write(&css_set_rwsem); + ret = cgroup_taskset_migrate(&tset, cgrp); out_finish: cgroup_migrate_finish(&preloaded_csets); percpu_up_write(&cgroup_threadgroup_rwsem);