Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull scheduler fixes from Ingo Molnar:
 "Two rq-clock warnings related fixes, plus a cgroups related crash fix"

* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched/cgroup: Move sched_online_group() back into css_online() to fix crash
  sched/fair: Update rq clock before changing a task's CPU affinity
  sched/core: Fix update_rq_clock() splat on hotplug (and suspend/resume)

1 files changed, 17 insertions, 12 deletions

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 6ea1925ac5c0..bbfb917a9b49 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -1090,6 +1090,7 @@ static int __set_cpus_allowed_ptr(struct task_struct *p,
         int ret = 0;
 
         rq = task_rq_lock(p, &rf);
+        update_rq_clock(rq);
 
         if (p->flags & PF_KTHREAD) {
                 /*
@@ -5560,7 +5561,7 @@ static void migrate_tasks(struct rq *dead_rq)
 {
         struct rq *rq = dead_rq;
         struct task_struct *next, *stop = rq->stop;
-        struct rq_flags rf, old_rf;
+        struct rq_flags rf;
         int dest_cpu;
 
         /*
@@ -5579,7 +5580,9 @@ static void migrate_tasks(struct rq *dead_rq)
          * class method both need to have an up-to-date
          * value of rq->clock[_task]
          */
+        rq_pin_lock(rq, &rf);
         update_rq_clock(rq);
+        rq_unpin_lock(rq, &rf);
 
         for (;;) {
                 /*
@@ -5592,7 +5595,7 @@ static void migrate_tasks(struct rq *dead_rq)
                 /*
                  * pick_next_task() assumes pinned rq->lock:
                  */
-                rq_pin_lock(rq, &rf);
+                rq_repin_lock(rq, &rf);
                 next = pick_next_task(rq, &fake_task, &rf);
                 BUG_ON(!next);
                 next->sched_class->put_prev_task(rq, next);
@@ -5621,13 +5624,6 @@ static void migrate_tasks(struct rq *dead_rq)
                         continue;
                 }
 
-                /*
-                 * __migrate_task() may return with a different
-                 * rq->lock held and a new cookie in 'rf', but we need
-                 * to preserve rf::clock_update_flags for 'dead_rq'.
-                 */
-                old_rf = rf;
-
                 /* Find suitable destination for @next, with force if needed. */
                 dest_cpu = select_fallback_rq(dead_rq->cpu, next);
 
@@ -5636,7 +5632,6 @@ static void migrate_tasks(struct rq *dead_rq)
                         raw_spin_unlock(&rq->lock);
                         rq = dead_rq;
                         raw_spin_lock(&rq->lock);
-                        rf = old_rf;
                 }
                 raw_spin_unlock(&next->pi_lock);
         }
@@ -6819,11 +6814,20 @@ cpu_cgroup_css_alloc(struct cgroup_subsys_state *parent_css)
         if (IS_ERR(tg))
                 return ERR_PTR(-ENOMEM);
 
-        sched_online_group(tg, parent);
-
         return &tg->css;
 }
 
+/* Expose task group only after completing cgroup initialization */
+static int cpu_cgroup_css_online(struct cgroup_subsys_state *css)
+{
+        struct task_group *tg = css_tg(css);
+        struct task_group *parent = css_tg(css->parent);
+
+        if (parent)
+                sched_online_group(tg, parent);
+        return 0;
+}
+
 static void cpu_cgroup_css_released(struct cgroup_subsys_state *css)
 {
         struct task_group *tg = css_tg(css);
@@ -7229,6 +7233,7 @@ static struct cftype cpu_files[] = {
 
 struct cgroup_subsys cpu_cgrp_subsys = {
         .css_alloc      = cpu_cgroup_css_alloc,
+        .css_online     = cpu_cgroup_css_online,
         .css_released   = cpu_cgroup_css_released,
         .css_free       = cpu_cgroup_css_free,
         .fork           = cpu_cgroup_fork,