- /*
- * 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);