sched: Fix latencytop and sleep profiling vs group scheduling

The latencytop and sleep accounting code assumes that any
scheduler entity represents a task, this is not so.

Cc: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 19 insertions, 13 deletions

diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
index 9ffb2b2ceba4..652e8bdef9aa 100644
--- a/kernel/sched_fair.c
+++ b/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
 }