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Add a defensive WARN_ON_ONCE() to catch any cases that > are not covered by the MIGRATING | MIGRATED | INITIAL flags. > > Fixes: b049b81bdff6 ("sched: Handle blocked-waiter migration (and return migration)") > Signed-off-by: K Prateek Nayak > --- > kernel/sched/fair.c | 10 ++++++++-- > 1 file changed, 8 insertions(+), 2 deletions(-) > > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c > index 244f1c68c041..ed397c259509 100644 > --- a/kernel/sched/fair.c > +++ b/kernel/sched/fair.c > @@ -5654,7 +5654,7 @@ static inline void update_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *s > decayed = update_cfs_rq_load_avg(now, cfs_rq); > decayed |= propagate_entity_load_avg(se); > > - if (!se->avg.last_update_time && (flags & DO_ATTACH)) { > + if (flags & DO_ATTACH) { > > /* > * DO_ATTACH means we're here from enqueue_entity(). nit: the comment below still says: * !last_update_time means we've passed through * migrate_task_rq_fair() indicating we migrated. We should probably update it, perhaps: /* * DO_ATTACH means the entity needs to be attached to this * cfs_rq's load-tracking sums, either on initial enqueue * or after migration. */ or something along these lines. > @@ -6110,6 +6110,7 @@ static void > enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags) > { > bool curr = cfs_rq->curr == se; > + int action = UPDATE_TG; > > /* > * If we're the current task, we must renormalise before calling > @@ -6120,6 +6121,11 @@ enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags) > > update_curr(cfs_rq); > > + if (flags & (ENQUEUE_MIGRATING | ENQUEUE_MIGRATED | ENQUEUE_INITIAL)) > + action |= DO_ATTACH; > + else > + WARN_ON_ONCE(!se->avg.last_update_time); > + > /* > * When enqueuing a sched_entity, we must: > * - Update loads to have both entity and cfs_rq synced with now. > @@ -6129,7 +6135,7 @@ enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags) > * its group cfs_rq > * - Add its new weight to cfs_rq->load.weight > */ > - update_load_avg(cfs_rq, se, UPDATE_TG | DO_ATTACH); > + update_load_avg(cfs_rq, se, action); > se_update_runnable(se); > /* > * XXX update_load_avg() above will have attached us to the pelt sum; > -- > 2.34.1 > Thanks, -Andrea