Merge branch 'core-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

* 'core-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  sched: silence PROVE_RCU in sched_fork()
  idr: fix RCU lockdep splat in idr_get_next()
  rcu: apply RCU protection to wake_affine()

3 files changed, 13 insertions, 2 deletions

diff --git a/kernel/sched.c b/kernel/sched.c
index f8b8996228dd..a2d215d132f6 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -2494,7 +2494,16 @@ void sched_fork(struct task_struct *p, int clone_flags)
         if (p->sched_class->task_fork)
                 p->sched_class->task_fork(p);
 
+        /*
+         * The child is not yet in the pid-hash so no cgroup attach races,
+         * and the cgroup is pinned to this child due to cgroup_fork()
+         * is ran before sched_fork().
+         *
+         * Silence PROVE_RCU.
+         */
+        rcu_read_lock();
         set_task_cpu(p, cpu);
+        rcu_read_unlock();
 
 #if defined(CONFIG_SCHEDSTATS) || defined(CONFIG_TASK_DELAY_ACCT)
         if (likely(sched_info_on()))
diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
index eed35eded602..a878b5332daa 100644
--- a/kernel/sched_fair.c
+++ b/kernel/sched_fair.c
@@ -1240,6 +1240,7 @@ static int wake_affine(struct sched_domain *sd, struct task_struct *p, int sync)
          * effect of the currently running task from the load
          * of the current CPU:
          */
+        rcu_read_lock();
         if (sync) {
                 tg = task_group(current);
                 weight = current->se.load.weight;
@@ -1275,6 +1276,7 @@ static int wake_affine(struct sched_domain *sd, struct task_struct *p, int sync)
                 balanced = this_eff_load <= prev_eff_load;
         } else
                 balanced = true;
+        rcu_read_unlock();
 
         /*
          * If the currently running task will sleep within
diff --git a/lib/idr.c b/lib/idr.c
index c1a206901761..7f1a4f0acf50 100644
--- a/lib/idr.c
+++ b/lib/idr.c
@@ -602,7 +602,7 @@ void *idr_get_next(struct idr *idp, int *nextidp)
         /* find first ent */
         n = idp->layers * IDR_BITS;
         max = 1 << n;
-        p = rcu_dereference(idp->top);
+        p = rcu_dereference_raw(idp->top);
         if (!p)
                 return NULL;
 
@@ -610,7 +610,7 @@ void *idr_get_next(struct idr *idp, int *nextidp)
                 while (n > 0 && p) {
                         n -= IDR_BITS;
                         *paa++ = p;
-                        p = rcu_dereference(p->ary[(id >> n) & IDR_MASK]);
+                        p = rcu_dereference_raw(p->ary[(id >> n) & IDR_MASK]);
                 }
 
                 if (p) {