Merge branch 'sched-fixes-for-linus' of git://git.kernel.org/pub/scm/…

…linux/kernel/git/tip/linux-2.6-tip

* 'sched-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  sched: Fix race in cpupri introduced by cpumask_var changes
  sched: Fix latencytop and sleep profiling vs group scheduling

kernel/sched_cpupri.c

@@ -81,8 +81,21 @@ int cpupri_find(struct cpupri *cp, struct task_struct *p,
 		if (cpumask_any_and(&p->cpus_allowed, vec->mask) >= nr_cpu_ids)
 			continue;
 
-		if (lowest_mask)
+		if (lowest_mask) {
 			cpumask_and(lowest_mask, &p->cpus_allowed, vec->mask);
+
+			/*
+			 * We have to ensure that we have at least one bit
+			 * still set in the array, since the map could have
+			 * been concurrently emptied between the first and
+			 * second reads of vec->mask.  If we hit this
+			 * condition, simply act as though we never hit this
+			 * priority level and continue on.
+			 */
+			if (cpumask_any(lowest_mask) >= nr_cpu_ids)
+				continue;
+		}
+
 		return 1;
 	}
 

kernel/sched_fair.c

@@ -611,9 +611,13 @@ account_entity_dequeue(struct cfs_rq *cfs_rq, struct sched_entity *se)
 static void enqueue_sleeper(struct cfs_rq *cfs_rq, struct sched_entity *se)
 {
 #ifdef CONFIG_SCHEDSTATS
+	struct task_struct *tsk = NULL;
+
+	if (entity_is_task(se))
+		tsk = task_of(se);
+
 	if (se->sleep_start) {
 		u64 delta = rq_of(cfs_rq)->clock - se->sleep_start;
-		struct task_struct *tsk = task_of(se);
 
 		if ((s64)delta < 0)
 			delta = 0;
@@ -624,11 +628,11 @@ static void enqueue_sleeper(struct cfs_rq *cfs_rq, struct sched_entity *se)
 		se->sleep_start = 0;
 		se->sum_sleep_runtime += delta;
 
-		account_scheduler_latency(tsk, delta >> 10, 1);
+		if (tsk)
+			account_scheduler_latency(tsk, delta >> 10, 1);
 	}
 	if (se->block_start) {
 		u64 delta = rq_of(cfs_rq)->clock - se->block_start;
-		struct task_struct *tsk = task_of(se);
 
 		if ((s64)delta < 0)
 			delta = 0;
@@ -639,17 +643,19 @@ static void enqueue_sleeper(struct cfs_rq *cfs_rq, struct sched_entity *se)
 		se->block_start = 0;
 		se->sum_sleep_runtime += delta;
 
-		/*
-		 * Blocking time is in units of nanosecs, so shift by 20 to
-		 * get a milliseconds-range estimation of the amount of
-		 * time that the task spent sleeping:
-		 */
-		if (unlikely(prof_on == SLEEP_PROFILING)) {
-
-			profile_hits(SLEEP_PROFILING, (void *)get_wchan(tsk),
-				     delta >> 20);
+		if (tsk) {
+			/*
+			 * Blocking time is in units of nanosecs, so shift by
+			 * 20 to get a milliseconds-range estimation of the
+			 * amount of time that the task spent sleeping:
+			 */
+			if (unlikely(prof_on == SLEEP_PROFILING)) {
+				profile_hits(SLEEP_PROFILING,
+						(void *)get_wchan(tsk),
+						delta >> 20);
+			}
+			account_scheduler_latency(tsk, delta >> 10, 0);
 		}
-		account_scheduler_latency(tsk, delta >> 10, 0);
 	}
 #endif
 }