as part of enqueue_entity both a new entity weight and its contribution to the queuing cfs_rq / rq are updated. Since update_cfs_shares will only update the queueing weights when the entity is on_rq (which in this case it is not yet), there's a dependency loop here: update_cfs_shares needs account_entity_enqueue to update cfs_rq->load.weight account_entity_enqueue needs the updated weight for the queuing cfs_rq load[*] Fix this and avoid spurious dequeue/enqueues by issuing update_cfs_shares as if we had accounted the enqueue already. This was also resulting in rq->load corruption previously. [*]: this dependency also exists when using the group cfs_rq w/ update_cfs_shares as the weight of the enqueued entity changes without the load being updated. Signed-off-by: Paul Turner --- kernel/sched_fair.c | 16 ++++++++-------- 1 file changed, 8 insertions(+), 8 deletions(-) Index: kernel/sched_fair.c =================================================================== --- kernel/sched_fair.c.orig +++ kernel/sched_fair.c @@ -718,7 +718,7 @@ static void reweight_entity(struct cfs_r account_entity_enqueue(cfs_rq, se); } -static void update_cfs_shares(struct cfs_rq *cfs_rq) +static void update_cfs_shares(struct cfs_rq *cfs_rq, long weight_delta) { struct task_group *tg; struct sched_entity *se; @@ -732,7 +732,7 @@ static void update_cfs_shares(struct cfs if (!se) return; - load = cfs_rq->load.weight; + load = cfs_rq->load.weight + weight_delta; load_weight = atomic_read(&tg->load_weight); load_weight -= cfs_rq->load_contribution; @@ -754,7 +754,7 @@ static inline void update_cfs_load(struc { } -static inline void update_cfs_shares(struct cfs_rq *cfs_rq) +static inline void update_cfs_shares(struct cfs_rq *cfs_rq, long weight_delta) { } #endif /* CONFIG_FAIR_GROUP_SCHED */ @@ -881,8 +881,8 @@ enqueue_entity(struct cfs_rq *cfs_rq, st */ update_curr(cfs_rq); update_cfs_load(cfs_rq, 0); + update_cfs_shares(cfs_rq_of(se), se->load.weight); account_entity_enqueue(cfs_rq, se); - update_cfs_shares(cfs_rq_of(se)); if (flags & ENQUEUE_WAKEUP) { place_entity(cfs_rq, se, 0); @@ -944,7 +944,7 @@ dequeue_entity(struct cfs_rq *cfs_rq, st update_cfs_load(cfs_rq, 0); account_entity_dequeue(cfs_rq, se); update_min_vruntime(cfs_rq); - update_cfs_shares(cfs_rq_of(se)); + update_cfs_shares(cfs_rq_of(se), 0); /* * Normalize the entity after updating the min_vruntime because the @@ -1177,7 +1177,7 @@ enqueue_task_fair(struct rq *rq, struct struct cfs_rq *cfs_rq = cfs_rq_of(se); update_cfs_load(cfs_rq, 0); - update_cfs_shares(cfs_rq); + update_cfs_shares(cfs_rq, 0); } hrtick_update(rq); @@ -1207,7 +1207,7 @@ static void dequeue_task_fair(struct rq struct cfs_rq *cfs_rq = cfs_rq_of(se); update_cfs_load(cfs_rq, 0); - update_cfs_shares(cfs_rq); + update_cfs_shares(cfs_rq, 0); } hrtick_update(rq); @@ -2030,7 +2030,7 @@ static int tg_shares_up(struct task_grou * We need to update shares after updating tg->load_weight in * order to adjust the weight of groups with long running tasks. */ - update_cfs_shares(cfs_rq); + update_cfs_shares(cfs_rq, 0); raw_spin_unlock_irqrestore(&rq->lock, flags); -- -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/