sched/deadline: Ensure that updates to exclusive cpusets don't break AC

[firefly-linux-kernel-4.4.55.git] / kernel / cpuset.c

diff --git a/kernel/cpuset.c b/kernel/cpuset.c
index 1f107c74087bc52f690d957dbe610472688b4c1b..723cfc9d0ad7ac417fdeb6ea2824f00129bcfaa1 100644 (file)
--- a/kernel/cpuset.c
+++ b/kernel/cpuset.c
@@ -506,6 +506,16 @@ static int validate_change(struct cpuset *cur, struct cpuset *trial)
                        goto out;
        }
 
+       /*
+        * We can't shrink if we won't have enough room for SCHED_DEADLINE
+        * tasks.
+        */
+       ret = -EBUSY;
+       if (is_cpu_exclusive(cur) &&
+           !cpuset_cpumask_can_shrink(cur->cpus_allowed,
+                                      trial->cpus_allowed))
+               goto out;
+
        ret = 0;
 out:
        rcu_read_unlock();
@@ -1429,17 +1439,8 @@ static int cpuset_can_attach(struct cgroup_subsys_state *css,
                goto out_unlock;
 
        cgroup_taskset_for_each(task, tset) {
-               /*
-                * Kthreads which disallow setaffinity shouldn't be moved
-                * to a new cpuset; we don't want to change their cpu
-                * affinity and isolating such threads by their set of
-                * allowed nodes is unnecessary.  Thus, cpusets are not
-                * applicable for such threads.  This prevents checking for
-                * success of set_cpus_allowed_ptr() on all attached tasks
-                * before cpus_allowed may be changed.
-                */
-               ret = -EINVAL;
-               if (task->flags & PF_NO_SETAFFINITY)
+               ret = task_can_attach(task, cs->cpus_allowed);
+               if (ret)
                        goto out_unlock;
                ret = security_task_setscheduler(task);
                if (ret)