If we want to use schedstats facility, we should move out of
struct sched_statistics from the struct sched_entity or add it into other
sctructs of sched entity as well. Obviously the latter one is bad because
that requires more spaces. So we should move it into a common struct which
can be used by all sched classes.

The struct sched_statistics is the schedular statistics of a task_struct
or a task_group. So we can move it into struct task_struct and
struct task_group to achieve the goal.

Below is the detailed explaination of the change in the structs.

- Before this patch

struct task_struct {            |-> struct sched_entity {
    ...                         |       ...
    struct sched_entity *se; ---|       struct sched_statistics statistics;
    struct sched_rt_entity *rt;         ...
    ...                                 ...
};                                  };

struct task_group {             |--> se[0]->statistics : schedstats of CPU0
    ...                         |
 #ifdef CONFIG_FAIR_GROUP_SCHED |
    struct sched_entity **se; --|--> se[1]->statistics : schedstats of CPU1
                                |
 #endif                         |
                                |--> se[N]->statistics : schedstats of CPUn

 #ifdef CONFIG_FAIR_GROUP_SCHED
    struct sched_rt_entity  **rt_se; (N/A)
 #endif
    ...
};

The '**se' in task_group is allocated in the fair sched class, which is
hard to be reused by other sched class.

- After this patch

struct task_struct {
    ...
    struct sched_statistics statistics;
    ...
    struct sched_entity *se;
    struct sched_rt_entity *rt;
    ...
};

struct task_group {                    |---> stats[0] : of CPU0
    ...                                |
    struct sched_statistics **stats; --|---> stats[1] : of CPU1
    ...                                |
                                       |---> stats[n] : of CPUn
 #ifdef CONFIG_FAIR_GROUP_SCHED
    struct sched_entity **se;
 #endif
 #ifdef CONFIG_RT_GROUP_SCHED
    struct sched_rt_entity  **rt_se;
 #endif
    ...
};

After the patch it is clearly that both of se or rt_se can easily get the
sched_statistics by a task_struct or a task_group.

Signed-off-by: Yafang Shao <laoar.s...@gmail.com>
---
 include/linux/sched.h    |   3 +-
 kernel/sched/core.c      |  24 ++++---
 kernel/sched/deadline.c  |   4 +-
 kernel/sched/debug.c     |  81 +++++++++++-----------
 kernel/sched/fair.c      | 142 ++++++++++++++++++++++++++-------------
 kernel/sched/rt.c        |   4 +-
 kernel/sched/sched.h     |   3 +
 kernel/sched/stats.h     |  46 +++++++++++++
 kernel/sched/stop_task.c |   4 +-
 9 files changed, 206 insertions(+), 105 deletions(-)

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 063cd120b459..f8e969be4bee 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -462,8 +462,6 @@ struct sched_entity {
 
        u64                             nr_migrations;
 
-       struct sched_statistics         statistics;
-
 #ifdef CONFIG_FAIR_GROUP_SCHED
        int                             depth;
        struct sched_entity             *parent;
@@ -681,6 +679,7 @@ struct task_struct {
        unsigned int                    rt_priority;
 
        const struct sched_class        *sched_class;
+       struct sched_statistics         stats;
        struct sched_entity             se;
        struct sched_rt_entity          rt;
 #ifdef CONFIG_CGROUP_SCHED
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index fd76628778f7..081b4f1f2cb4 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -2427,11 +2427,11 @@ ttwu_stat(struct task_struct *p, int cpu, int 
wake_flags)
 #ifdef CONFIG_SMP
        if (cpu == rq->cpu) {
                __schedstat_inc(rq->ttwu_local);
-               __schedstat_inc(p->se.statistics.nr_wakeups_local);
+               __schedstat_inc(p->stats.nr_wakeups_local);
        } else {
                struct sched_domain *sd;
 
-               __schedstat_inc(p->se.statistics.nr_wakeups_remote);
+               __schedstat_inc(p->stats.nr_wakeups_remote);
                rcu_read_lock();
                for_each_domain(rq->cpu, sd) {
                        if (cpumask_test_cpu(cpu, sched_domain_span(sd))) {
@@ -2443,14 +2443,14 @@ ttwu_stat(struct task_struct *p, int cpu, int 
wake_flags)
        }
 
        if (wake_flags & WF_MIGRATED)
-               __schedstat_inc(p->se.statistics.nr_wakeups_migrate);
+               __schedstat_inc(p->stats.nr_wakeups_migrate);
 #endif /* CONFIG_SMP */
 
        __schedstat_inc(rq->ttwu_count);
-       __schedstat_inc(p->se.statistics.nr_wakeups);
+       __schedstat_inc(p->stats.nr_wakeups);
 
        if (wake_flags & WF_SYNC)
-               __schedstat_inc(p->se.statistics.nr_wakeups_sync);
+               __schedstat_inc(p->stats.nr_wakeups_sync);
 }
 
 /*
@@ -3075,7 +3075,7 @@ static void __sched_fork(unsigned long clone_flags, 
struct task_struct *p)
 
 #ifdef CONFIG_SCHEDSTATS
        /* Even if schedstat is disabled, there should not be garbage */
-       memset(&p->se.statistics, 0, sizeof(p->se.statistics));
+       memset(&p->stats, 0, sizeof(p->stats));
 #endif
 
        RB_CLEAR_NODE(&p->dl.rb_node);
@@ -7347,9 +7347,9 @@ void normalize_rt_tasks(void)
                        continue;
 
                p->se.exec_start = 0;
-               schedstat_set(p->se.statistics.wait_start,  0);
-               schedstat_set(p->se.statistics.sleep_start, 0);
-               schedstat_set(p->se.statistics.block_start, 0);
+               schedstat_set(p->stats.wait_start,  0);
+               schedstat_set(p->stats.sleep_start, 0);
+               schedstat_set(p->stats.block_start, 0);
 
                if (!dl_task(p) && !rt_task(p)) {
                        /*
@@ -7439,6 +7439,7 @@ static void sched_free_group(struct task_group *tg)
 {
        free_fair_sched_group(tg);
        free_rt_sched_group(tg);
+       free_tg_schedstats(tg);
        autogroup_free(tg);
        kmem_cache_free(task_group_cache, tg);
 }
@@ -7458,6 +7459,9 @@ struct task_group *sched_create_group(struct task_group 
*parent)
        if (!alloc_rt_sched_group(tg, parent))
                goto err;
 
+       if (!alloc_tg_schedstats(tg))
+               goto err;
+
        alloc_uclamp_sched_group(tg, parent);
 
        return tg;
@@ -8144,7 +8148,7 @@ static int cpu_cfs_stat_show(struct seq_file *sf, void *v)
                int i;
 
                for_each_possible_cpu(i)
-                       ws += schedstat_val(tg->se[i]->statistics.wait_sum);
+                       ws += schedstat_val(tg->stats[i]->wait_sum);
 
                seq_printf(sf, "wait_sum %llu\n", ws);
        }
diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
index 7a0124f81a4f..315d140b8f0e 100644
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -1245,8 +1245,8 @@ static void update_curr_dl(struct rq *rq)
                return;
        }
 
-       schedstat_set(curr->se.statistics.exec_max,
-                     max(curr->se.statistics.exec_max, delta_exec));
+       schedstat_set(curr->stats.exec_max,
+                     max(curr->stats.exec_max, delta_exec));
 
        curr->se.sum_exec_runtime += delta_exec;
        account_group_exec_runtime(curr, delta_exec);
diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c
index 9758aa1bba1e..8c646fcb89de 100644
--- a/kernel/sched/debug.c
+++ b/kernel/sched/debug.c
@@ -444,16 +444,16 @@ static void print_cfs_group_stats(struct seq_file *m, int 
cpu, struct task_group
        PN(se->sum_exec_runtime);
 
        if (schedstat_enabled()) {
-               PN_SCHEDSTAT(se->statistics.wait_start);
-               PN_SCHEDSTAT(se->statistics.sleep_start);
-               PN_SCHEDSTAT(se->statistics.block_start);
-               PN_SCHEDSTAT(se->statistics.sleep_max);
-               PN_SCHEDSTAT(se->statistics.block_max);
-               PN_SCHEDSTAT(se->statistics.exec_max);
-               PN_SCHEDSTAT(se->statistics.slice_max);
-               PN_SCHEDSTAT(se->statistics.wait_max);
-               PN_SCHEDSTAT(se->statistics.wait_sum);
-               P_SCHEDSTAT(se->statistics.wait_count);
+               PN_SCHEDSTAT(tg->stats[cpu]->wait_start);
+               PN_SCHEDSTAT(tg->stats[cpu]->sleep_start);
+               PN_SCHEDSTAT(tg->stats[cpu]->block_start);
+               PN_SCHEDSTAT(tg->stats[cpu]->sleep_max);
+               PN_SCHEDSTAT(tg->stats[cpu]->block_max);
+               PN_SCHEDSTAT(tg->stats[cpu]->exec_max);
+               PN_SCHEDSTAT(tg->stats[cpu]->slice_max);
+               PN_SCHEDSTAT(tg->stats[cpu]->wait_max);
+               PN_SCHEDSTAT(tg->stats[cpu]->wait_sum);
+               P_SCHEDSTAT(tg->stats[cpu]->wait_count);
        }
 
        P(se->load.weight);
@@ -499,9 +499,9 @@ print_task(struct seq_file *m, struct rq *rq, struct 
task_struct *p)
                p->prio);
 
        SEQ_printf(m, "%9Ld.%06ld %9Ld.%06ld %9Ld.%06ld",
-               SPLIT_NS(schedstat_val_or_zero(p->se.statistics.wait_sum)),
+               SPLIT_NS(schedstat_val_or_zero(p->stats.wait_sum)),
                SPLIT_NS(p->se.sum_exec_runtime),
-               
SPLIT_NS(schedstat_val_or_zero(p->se.statistics.sum_sleep_runtime)));
+               SPLIT_NS(schedstat_val_or_zero(p->stats.sum_sleep_runtime)));
 
 #ifdef CONFIG_NUMA_BALANCING
        SEQ_printf(m, " %d %d", task_node(p), task_numa_group_id(p));
@@ -938,34 +938,33 @@ void proc_sched_show_task(struct task_struct *p, struct 
pid_namespace *ns,
 
        if (schedstat_enabled()) {
                u64 avg_atom, avg_per_cpu;
-
-               PN_SCHEDSTAT(se.statistics.sum_sleep_runtime);
-               PN_SCHEDSTAT(se.statistics.wait_start);
-               PN_SCHEDSTAT(se.statistics.sleep_start);
-               PN_SCHEDSTAT(se.statistics.block_start);
-               PN_SCHEDSTAT(se.statistics.sleep_max);
-               PN_SCHEDSTAT(se.statistics.block_max);
-               PN_SCHEDSTAT(se.statistics.exec_max);
-               PN_SCHEDSTAT(se.statistics.slice_max);
-               PN_SCHEDSTAT(se.statistics.wait_max);
-               PN_SCHEDSTAT(se.statistics.wait_sum);
-               P_SCHEDSTAT(se.statistics.wait_count);
-               PN_SCHEDSTAT(se.statistics.iowait_sum);
-               P_SCHEDSTAT(se.statistics.iowait_count);
-               P_SCHEDSTAT(se.statistics.nr_migrations_cold);
-               P_SCHEDSTAT(se.statistics.nr_failed_migrations_affine);
-               P_SCHEDSTAT(se.statistics.nr_failed_migrations_running);
-               P_SCHEDSTAT(se.statistics.nr_failed_migrations_hot);
-               P_SCHEDSTAT(se.statistics.nr_forced_migrations);
-               P_SCHEDSTAT(se.statistics.nr_wakeups);
-               P_SCHEDSTAT(se.statistics.nr_wakeups_sync);
-               P_SCHEDSTAT(se.statistics.nr_wakeups_migrate);
-               P_SCHEDSTAT(se.statistics.nr_wakeups_local);
-               P_SCHEDSTAT(se.statistics.nr_wakeups_remote);
-               P_SCHEDSTAT(se.statistics.nr_wakeups_affine);
-               P_SCHEDSTAT(se.statistics.nr_wakeups_affine_attempts);
-               P_SCHEDSTAT(se.statistics.nr_wakeups_passive);
-               P_SCHEDSTAT(se.statistics.nr_wakeups_idle);
+               PN_SCHEDSTAT(stats.sum_sleep_runtime);
+               PN_SCHEDSTAT(stats.wait_start);
+               PN_SCHEDSTAT(stats.sleep_start);
+               PN_SCHEDSTAT(stats.block_start);
+               PN_SCHEDSTAT(stats.sleep_max);
+               PN_SCHEDSTAT(stats.block_max);
+               PN_SCHEDSTAT(stats.exec_max);
+               PN_SCHEDSTAT(stats.slice_max);
+               PN_SCHEDSTAT(stats.wait_max);
+               PN_SCHEDSTAT(stats.wait_sum);
+               P_SCHEDSTAT(stats.wait_count);
+               PN_SCHEDSTAT(stats.iowait_sum);
+               P_SCHEDSTAT(stats.iowait_count);
+               P_SCHEDSTAT(stats.nr_migrations_cold);
+               P_SCHEDSTAT(stats.nr_failed_migrations_affine);
+               P_SCHEDSTAT(stats.nr_failed_migrations_running);
+               P_SCHEDSTAT(stats.nr_failed_migrations_hot);
+               P_SCHEDSTAT(stats.nr_forced_migrations);
+               P_SCHEDSTAT(stats.nr_wakeups);
+               P_SCHEDSTAT(stats.nr_wakeups_sync);
+               P_SCHEDSTAT(stats.nr_wakeups_migrate);
+               P_SCHEDSTAT(stats.nr_wakeups_local);
+               P_SCHEDSTAT(stats.nr_wakeups_remote);
+               P_SCHEDSTAT(stats.nr_wakeups_affine);
+               P_SCHEDSTAT(stats.nr_wakeups_affine_attempts);
+               P_SCHEDSTAT(stats.nr_wakeups_passive);
+               P_SCHEDSTAT(stats.nr_wakeups_idle);
 
                avg_atom = p->se.sum_exec_runtime;
                if (nr_switches)
@@ -1031,6 +1030,6 @@ void proc_sched_show_task(struct task_struct *p, struct 
pid_namespace *ns,
 void proc_sched_set_task(struct task_struct *p)
 {
 #ifdef CONFIG_SCHEDSTATS
-       memset(&p->se.statistics, 0, sizeof(p->se.statistics));
+       memset(&p->stats, 0, sizeof(p->stats));
 #endif
 }
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 7e7c03cede94..14d8df308d44 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -837,12 +837,44 @@ static void update_tg_load_avg(struct cfs_rq *cfs_rq)
 }
 #endif /* CONFIG_SMP */
 
+static inline void
+__schedstat_from_sched_entity(struct sched_entity *se,
+                             struct sched_statistics **stats)
+{
+       struct task_struct *p;
+       struct task_group *tg;
+       struct cfs_rq *cfs_rq;
+       int cpu;
+
+       if (entity_is_task(se)) {
+               p = task_of(se);
+               *stats = &p->stats;
+       } else {
+               cfs_rq = group_cfs_rq(se);
+               tg = cfs_rq->tg;
+               cpu = cpu_of(rq_of(cfs_rq));
+               *stats = tg->stats[cpu];
+       }
+}
+
+static inline void
+schedstat_from_sched_entity(struct sched_entity *se,
+                           struct sched_statistics **stats)
+{
+       if (!schedstat_enabled())
+               return;
+
+       __schedstat_from_sched_entity(se, stats);
+}
+
 /*
  * Update the current task's runtime statistics.
  */
 static void update_curr(struct cfs_rq *cfs_rq)
 {
        struct sched_entity *curr = cfs_rq->curr;
+       struct sched_statistics *stats = NULL;
+
        u64 now = rq_clock_task(rq_of(cfs_rq));
        u64 delta_exec;
 
@@ -855,8 +887,12 @@ static void update_curr(struct cfs_rq *cfs_rq)
 
        curr->exec_start = now;
 
-       schedstat_set(curr->statistics.exec_max,
-                     max(delta_exec, curr->statistics.exec_max));
+       if (schedstat_enabled()) {
+               __schedstat_from_sched_entity(curr, &stats);
+
+               __schedstat_set(stats->exec_max,
+                     max(delta_exec, stats->exec_max));
+       }
 
        curr->sum_exec_runtime += delta_exec;
        schedstat_add(cfs_rq->exec_clock, delta_exec);
@@ -883,67 +919,78 @@ static void update_curr_fair(struct rq *rq)
 static inline void
 update_stats_wait_start(struct cfs_rq *cfs_rq, struct sched_entity *se)
 {
+       struct sched_statistics *stats = NULL;
        u64 wait_start, prev_wait_start;
 
        if (!schedstat_enabled())
                return;
 
+       __schedstat_from_sched_entity(se, &stats);
+
        wait_start = rq_clock(rq_of(cfs_rq));
-       prev_wait_start = schedstat_val(se->statistics.wait_start);
+       prev_wait_start = schedstat_val(stats->wait_start);
 
        if (entity_is_task(se) && task_on_rq_migrating(task_of(se)) &&
            likely(wait_start > prev_wait_start))
                wait_start -= prev_wait_start;
 
-       __schedstat_set(se->statistics.wait_start, wait_start);
+       __schedstat_set(stats->wait_start, wait_start);
 }
 
 static inline void
 update_stats_wait_end(struct cfs_rq *cfs_rq, struct sched_entity *se)
 {
-       struct task_struct *p;
+       struct sched_statistics *stats = NULL;
+       struct task_struct *p = NULL;
        u64 delta;
 
        if (!schedstat_enabled())
                return;
 
-       delta = rq_clock(rq_of(cfs_rq)) - 
schedstat_val(se->statistics.wait_start);
+       __schedstat_from_sched_entity(se, &stats);
 
+       delta = rq_clock(rq_of(cfs_rq)) - schedstat_val(stats->wait_start);
        if (entity_is_task(se)) {
                p = task_of(se);
+
                if (task_on_rq_migrating(p)) {
                        /*
                         * Preserve migrating task's wait time so wait_start
                         * time stamp can be adjusted to accumulate wait time
                         * prior to migration.
                         */
-                       __schedstat_set(se->statistics.wait_start, delta);
+                       __schedstat_set(stats->wait_start, delta);
+
                        return;
                }
+
                trace_sched_stat_wait(p, delta);
        }
 
-       __schedstat_set(se->statistics.wait_max,
-                     max(schedstat_val(se->statistics.wait_max), delta));
-       __schedstat_inc(se->statistics.wait_count);
-       __schedstat_add(se->statistics.wait_sum, delta);
-       __schedstat_set(se->statistics.wait_start, 0);
+       __schedstat_set(stats->wait_max,
+                       max(schedstat_val(stats->wait_max), delta));
+       __schedstat_inc(stats->wait_count);
+       __schedstat_add(stats->wait_sum, delta);
+       __schedstat_set(stats->wait_start, 0);
 }
 
 static inline void
 update_stats_enqueue_sleeper(struct cfs_rq *cfs_rq, struct sched_entity *se)
 {
-       struct task_struct *tsk = NULL;
+       struct sched_statistics *stats = NULL;
+       struct task_struct *p = NULL;
        u64 sleep_start, block_start;
 
        if (!schedstat_enabled())
                return;
 
-       sleep_start = schedstat_val(se->statistics.sleep_start);
-       block_start = schedstat_val(se->statistics.block_start);
-
        if (entity_is_task(se))
-               tsk = task_of(se);
+               p = task_of(se);
+
+       __schedstat_from_sched_entity(se, &stats);
+
+       sleep_start = schedstat_val(stats->sleep_start);
+       block_start = schedstat_val(stats->block_start);
 
        if (sleep_start) {
                u64 delta = rq_clock(rq_of(cfs_rq)) - sleep_start;
@@ -951,15 +998,15 @@ update_stats_enqueue_sleeper(struct cfs_rq *cfs_rq, 
struct sched_entity *se)
                if ((s64)delta < 0)
                        delta = 0;
 
-               if (unlikely(delta > schedstat_val(se->statistics.sleep_max)))
-                       __schedstat_set(se->statistics.sleep_max, delta);
+               if (unlikely(delta > schedstat_val(stats->sleep_max)))
+                       __schedstat_set(stats->sleep_max, delta);
 
-               __schedstat_set(se->statistics.sleep_start, 0);
-               __schedstat_add(se->statistics.sum_sleep_runtime, delta);
+               __schedstat_set(stats->sleep_start, 0);
+               __schedstat_add(stats->sum_sleep_runtime, delta);
 
-               if (tsk) {
-                       account_scheduler_latency(tsk, delta >> 10, 1);
-                       trace_sched_stat_sleep(tsk, delta);
+               if (p) {
+                       account_scheduler_latency(p, delta >> 10, 1);
+                       trace_sched_stat_sleep(p, delta);
                }
        }
        if (block_start) {
@@ -968,20 +1015,20 @@ update_stats_enqueue_sleeper(struct cfs_rq *cfs_rq, 
struct sched_entity *se)
                if ((s64)delta < 0)
                        delta = 0;
 
-               if (unlikely(delta > schedstat_val(se->statistics.block_max)))
-                       __schedstat_set(se->statistics.block_max, delta);
+               if (unlikely(delta > schedstat_val(stats->block_max)))
+                       __schedstat_set(stats->block_max, delta);
 
-               __schedstat_set(se->statistics.block_start, 0);
-               __schedstat_add(se->statistics.sum_sleep_runtime, delta);
+               __schedstat_set(stats->block_start, 0);
+               __schedstat_add(stats->sum_sleep_runtime, delta);
 
-               if (tsk) {
-                       if (tsk->in_iowait) {
-                               __schedstat_add(se->statistics.iowait_sum, 
delta);
-                               __schedstat_inc(se->statistics.iowait_count);
-                               trace_sched_stat_iowait(tsk, delta);
+               if (p) {
+                       if (p->in_iowait) {
+                               __schedstat_add(stats->iowait_sum, delta);
+                               __schedstat_inc(stats->iowait_count);
+                               trace_sched_stat_iowait(p, delta);
                        }
 
-                       trace_sched_stat_blocked(tsk, delta);
+                       trace_sched_stat_blocked(p, delta);
 
                        /*
                         * Blocking time is in units of nanosecs, so shift by
@@ -990,10 +1037,10 @@ update_stats_enqueue_sleeper(struct cfs_rq *cfs_rq, 
struct sched_entity *se)
                         */
                        if (unlikely(prof_on == SLEEP_PROFILING)) {
                                profile_hits(SLEEP_PROFILING,
-                                               (void *)get_wchan(tsk),
+                                               (void *)get_wchan(p),
                                                delta >> 20);
                        }
-                       account_scheduler_latency(tsk, delta >> 10, 0);
+                       account_scheduler_latency(p, delta >> 10, 0);
                }
        }
 }
@@ -1036,10 +1083,10 @@ update_stats_dequeue(struct cfs_rq *cfs_rq, struct 
sched_entity *se, int flags)
                struct task_struct *tsk = task_of(se);
 
                if (tsk->state & TASK_INTERRUPTIBLE)
-                       __schedstat_set(se->statistics.sleep_start,
+                       __schedstat_set(tsk->stats.sleep_start,
                                      rq_clock(rq_of(cfs_rq)));
                if (tsk->state & TASK_UNINTERRUPTIBLE)
-                       __schedstat_set(se->statistics.block_start,
+                       __schedstat_set(tsk->stats.block_start,
                                      rq_clock(rq_of(cfs_rq)));
        }
 }
@@ -4392,6 +4439,8 @@ check_preempt_tick(struct cfs_rq *cfs_rq, struct 
sched_entity *curr)
 static void
 set_next_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
 {
+       struct sched_statistics *stats = NULL;
+
        /* 'current' is not kept within the tree. */
        if (se->on_rq) {
                /*
@@ -4414,8 +4463,9 @@ set_next_entity(struct cfs_rq *cfs_rq, struct 
sched_entity *se)
         */
        if (schedstat_enabled() &&
            rq_of(cfs_rq)->cfs.load.weight >= 2*se->load.weight) {
-               __schedstat_set(se->statistics.slice_max,
-                       max((u64)schedstat_val(se->statistics.slice_max),
+               __schedstat_from_sched_entity(se, &stats);
+               __schedstat_set(stats->slice_max,
+                       max((u64)schedstat_val(stats->slice_max),
                            se->sum_exec_runtime - se->prev_sum_exec_runtime));
        }
 
@@ -5862,12 +5912,12 @@ static int wake_affine(struct sched_domain *sd, struct 
task_struct *p,
        if (sched_feat(WA_WEIGHT) && target == nr_cpumask_bits)
                target = wake_affine_weight(sd, p, this_cpu, prev_cpu, sync);
 
-       schedstat_inc(p->se.statistics.nr_wakeups_affine_attempts);
+       schedstat_inc(p->stats.nr_wakeups_affine_attempts);
        if (target == nr_cpumask_bits)
                return prev_cpu;
 
        schedstat_inc(sd->ttwu_move_affine);
-       schedstat_inc(p->se.statistics.nr_wakeups_affine);
+       schedstat_inc(p->stats.nr_wakeups_affine);
        return target;
 }
 
@@ -7533,7 +7583,7 @@ int can_migrate_task(struct task_struct *p, struct lb_env 
*env)
        if (!cpumask_test_cpu(env->dst_cpu, p->cpus_ptr)) {
                int cpu;
 
-               schedstat_inc(p->se.statistics.nr_failed_migrations_affine);
+               schedstat_inc(p->stats.nr_failed_migrations_affine);
 
                env->flags |= LBF_SOME_PINNED;
 
@@ -7564,7 +7614,7 @@ int can_migrate_task(struct task_struct *p, struct lb_env 
*env)
        env->flags &= ~LBF_ALL_PINNED;
 
        if (task_running(env->src_rq, p)) {
-               schedstat_inc(p->se.statistics.nr_failed_migrations_running);
+               schedstat_inc(p->stats.nr_failed_migrations_running);
                return 0;
        }
 
@@ -7582,12 +7632,12 @@ int can_migrate_task(struct task_struct *p, struct 
lb_env *env)
            env->sd->nr_balance_failed > env->sd->cache_nice_tries) {
                if (tsk_cache_hot == 1) {
                        schedstat_inc(env->sd->lb_hot_gained[env->idle]);
-                       schedstat_inc(p->se.statistics.nr_forced_migrations);
+                       schedstat_inc(p->stats.nr_forced_migrations);
                }
                return 1;
        }
 
-       schedstat_inc(p->se.statistics.nr_failed_migrations_hot);
+       schedstat_inc(p->stats.nr_failed_migrations_hot);
        return 0;
 }
 
diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
index af772ac0f32d..2d543a270dfe 100644
--- a/kernel/sched/rt.c
+++ b/kernel/sched/rt.c
@@ -1008,8 +1008,8 @@ static void update_curr_rt(struct rq *rq)
        if (unlikely((s64)delta_exec <= 0))
                return;
 
-       schedstat_set(curr->se.statistics.exec_max,
-                     max(curr->se.statistics.exec_max, delta_exec));
+       schedstat_set(curr->stats.exec_max,
+                     max(curr->stats.exec_max, delta_exec));
 
        curr->se.sum_exec_runtime += delta_exec;
        account_group_exec_runtime(curr, delta_exec);
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index 871544bb9a38..b1cdb942c67d 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -387,6 +387,9 @@ struct cfs_bandwidth {
 struct task_group {
        struct cgroup_subsys_state css;
 
+       /* schedstats of this group on each CPU */
+       struct sched_statistics **stats;
+
 #ifdef CONFIG_FAIR_GROUP_SCHED
        /* schedulable entities of this group on each CPU */
        struct sched_entity     **se;
diff --git a/kernel/sched/stats.h b/kernel/sched/stats.h
index c23b653ffc53..87242968712e 100644
--- a/kernel/sched/stats.h
+++ b/kernel/sched/stats.h
@@ -42,6 +42,42 @@ rq_sched_info_dequeued(struct rq *rq, unsigned long long 
delta)
 #define   schedstat_val(var)           (var)
 #define   schedstat_val_or_zero(var)   ((schedstat_enabled()) ? (var) : 0)
 
+static inline void free_tg_schedstats(struct task_group *tg)
+{
+       int i;
+
+       for_each_possible_cpu(i) {
+               if (tg->stats)
+                       kfree(tg->stats[i]);
+       }
+
+       kfree(tg->stats);
+}
+
+static inline int alloc_tg_schedstats(struct task_group *tg)
+{
+       struct sched_statistics *stats;
+       int i;
+
+       /*
+        * This memory should be allocated whatever schedstat_enabled() or
+        * not.
+        */
+       tg->stats = kcalloc(nr_cpu_ids, sizeof(stats), GFP_KERNEL);
+       if (!tg->stats)
+               return 0;
+
+       for_each_possible_cpu(i) {
+               stats = kzalloc_node(sizeof(struct sched_statistics),
+                                    GFP_KERNEL, cpu_to_node(i));
+               if (!stats)
+                       return 0;
+               tg->stats[i] = stats;
+       }
+
+       return 1;
+}
+
 #else /* !CONFIG_SCHEDSTATS: */
 static inline void rq_sched_info_arrive  (struct rq *rq, unsigned long long 
delta) { }
 static inline void rq_sched_info_dequeued(struct rq *rq, unsigned long long 
delta) { }
@@ -55,6 +91,16 @@ static inline void rq_sched_info_depart  (struct rq *rq, 
unsigned long long delt
 # define   schedstat_set(var, val)     do { } while (0)
 # define   schedstat_val(var)          0
 # define   schedstat_val_or_zero(var)  0
+
+static inline void free_tg_schedstats(struct task_group *tg)
+{
+}
+
+static inline int alloc_tg_schedstats(struct task_group *tg)
+{
+       return 1;
+}
+
 #endif /* CONFIG_SCHEDSTATS */
 
 #ifdef CONFIG_PSI
diff --git a/kernel/sched/stop_task.c b/kernel/sched/stop_task.c
index a5d289049388..f35cd67a0881 100644
--- a/kernel/sched/stop_task.c
+++ b/kernel/sched/stop_task.c
@@ -70,8 +70,8 @@ static void put_prev_task_stop(struct rq *rq, struct 
task_struct *prev)
        if (unlikely((s64)delta_exec < 0))
                delta_exec = 0;
 
-       schedstat_set(curr->se.statistics.exec_max,
-                       max(curr->se.statistics.exec_max, delta_exec));
+       schedstat_set(curr->stats.exec_max,
+                       max(curr->stats.exec_max, delta_exec));
 
        curr->se.sum_exec_runtime += delta_exec;
        account_group_exec_runtime(curr, delta_exec);
-- 
2.18.4

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