cgroup: freezer: don't change task and cgroups status unnecessarily

It's not necessary to adjust the task state and revisit the state of source and destination cgroups if the cgroups are not in freeze state and the task itself is not frozen. And in this scenario, it wakes up the task who's not supposed to be ready to run. Don't do the unnecessary task state adjustment can help stop waking up the task without a reason. Signed-off-by: Honglei Wang <[email protected]> Acked-by: Roman Gushchin <[email protected]> Signed-off-by: Tejun Heo <[email protected]>
torvalds · Nov 7, 2019 · 742e8cd · 742e8cd
1 parent 1bb5ec2
commit 742e8cd
Showing 1 changed file with 9 additions and 0 deletions.
diff --git a/kernel/cgroup/freezer.c b/kernel/cgroup/freezer.c
@@ -230,6 +230,15 @@ void cgroup_freezer_migrate_task(struct task_struct *task,
  if (task->flags & PF_KTHREAD)
  return;
 
+ /*
+ * It's not necessary to do changes if both of the src and dst cgroups
+ * are not freezing and task is not frozen.
+ */
+ if (!test_bit(CGRP_FREEZE, &src->flags) &&
+ !test_bit(CGRP_FREEZE, &dst->flags) &&
+ !task->frozen)
+ return;
+
  /*
  * Adjust counters of freezing and frozen tasks.
  * Note, that if the task is frozen, but the destination cgroup is not