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 f8b8996..a2d215d 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 eed35ed..a878b53 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 c1a2069..7f1a4f0 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) {