Merge branch 'for-5.15' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup

[linux-2.6-microblaze.git] / kernel / cgroup / cpuset.c

diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
index d497a65..df1ccf4 100644 (file)
--- a/kernel/cgroup/cpuset.c
+++ b/kernel/cgroup/cpuset.c
@@ -385,18 +385,29 @@ static inline bool is_in_v2_mode(void)
 }
 
 /*
- * Return in pmask the portion of a cpusets's cpus_allowed that
- * are online.  If none are online, walk up the cpuset hierarchy
- * until we find one that does have some online cpus.
+ * Return in pmask the portion of a task's cpusets's cpus_allowed that
+ * are online and are capable of running the task.  If none are found,
+ * walk up the cpuset hierarchy until we find one that does have some
+ * appropriate cpus.
  *
  * One way or another, we guarantee to return some non-empty subset
  * of cpu_online_mask.
  *
  * Call with callback_lock or cpuset_mutex held.
  */
-static void guarantee_online_cpus(struct cpuset *cs, struct cpumask *pmask)
+static void guarantee_online_cpus(struct task_struct *tsk,
+                                 struct cpumask *pmask)
 {
-       while (!cpumask_intersects(cs->effective_cpus, cpu_online_mask)) {
+       const struct cpumask *possible_mask = task_cpu_possible_mask(tsk);
+       struct cpuset *cs;
+
+       if (WARN_ON(!cpumask_and(pmask, possible_mask, cpu_online_mask)))
+               cpumask_copy(pmask, cpu_online_mask);
+
+       rcu_read_lock();
+       cs = task_cs(tsk);
+
+       while (!cpumask_intersects(cs->effective_cpus, pmask)) {
                cs = parent_cs(cs);
                if (unlikely(!cs)) {
                        /*
@@ -406,11 +417,13 @@ static void guarantee_online_cpus(struct cpuset *cs, struct cpumask *pmask)
                         * cpuset's effective_cpus is on its way to be
                         * identical to cpu_online_mask.
                         */
-                       cpumask_copy(pmask, cpu_online_mask);
-                       return;
+                       goto out_unlock;
                }
        }
-       cpumask_and(pmask, cs->effective_cpus, cpu_online_mask);
+       cpumask_and(pmask, pmask, cs->effective_cpus);
+
+out_unlock:
+       rcu_read_unlock();
 }
 
 /*
@@ -2227,15 +2240,13 @@ static void cpuset_attach(struct cgroup_taskset *tset)
 
        percpu_down_write(&cpuset_rwsem);
 
-       /* prepare for attach */
-       if (cs == &top_cpuset)
-               cpumask_copy(cpus_attach, cpu_possible_mask);
-       else
-               guarantee_online_cpus(cs, cpus_attach);
-
        guarantee_online_mems(cs, &cpuset_attach_nodemask_to);
 
        cgroup_taskset_for_each(task, css, tset) {
+               if (cs != &top_cpuset)
+                       guarantee_online_cpus(task, cpus_attach);
+               else
+                       cpumask_copy(cpus_attach, task_cpu_possible_mask(task));
                /*
                 * can_attach beforehand should guarantee that this doesn't
                 * fail.  TODO: have a better way to handle failure here
@@ -3352,9 +3363,7 @@ void cpuset_cpus_allowed(struct task_struct *tsk, struct cpumask *pmask)
        unsigned long flags;
 
        spin_lock_irqsave(&callback_lock, flags);
-       rcu_read_lock();
-       guarantee_online_cpus(task_cs(tsk), pmask);
-       rcu_read_unlock();
+       guarantee_online_cpus(tsk, pmask);
        spin_unlock_irqrestore(&callback_lock, flags);
 }
 
@@ -3368,13 +3377,22 @@ void cpuset_cpus_allowed(struct task_struct *tsk, struct cpumask *pmask)
  * which will not contain a sane cpumask during cases such as cpu hotplugging.
  * This is the absolute last resort for the scheduler and it is only used if
  * _every_ other avenue has been traveled.
+ *
+ * Returns true if the affinity of @tsk was changed, false otherwise.
  **/
 
-void cpuset_cpus_allowed_fallback(struct task_struct *tsk)
+bool cpuset_cpus_allowed_fallback(struct task_struct *tsk)
 {
+       const struct cpumask *possible_mask = task_cpu_possible_mask(tsk);
+       const struct cpumask *cs_mask;
+       bool changed = false;
+
        rcu_read_lock();
-       do_set_cpus_allowed(tsk, is_in_v2_mode() ?
-               task_cs(tsk)->cpus_allowed : cpu_possible_mask);
+       cs_mask = task_cs(tsk)->cpus_allowed;
+       if (is_in_v2_mode() && cpumask_subset(cs_mask, possible_mask)) {
+               do_set_cpus_allowed(tsk, cs_mask);
+               changed = true;
+       }
        rcu_read_unlock();
 
        /*
@@ -3394,6 +3412,7 @@ void cpuset_cpus_allowed_fallback(struct task_struct *tsk)
         * select_fallback_rq() will fix things ups and set cpu_possible_mask
         * if required.
         */
+       return changed;
 }
 
 void __init cpuset_init_current_mems_allowed(void)