On Fri 24-12-21 09:45:02, yukuai (C) wrote: > 在 2021/12/24 1:31, Jan Kara 写道: > > diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c > > index 056399185c2f..0da47f2ca781 100644 > > --- a/block/bfq-iosched.c > > +++ b/block/bfq-iosched.c > > @@ -2638,6 +2638,14 @@ bfq_setup_merge(struct bfq_queue *bfqq, struct bfq_queue *new_bfqq) > > if (process_refs == 0 || new_process_refs == 0) > > return NULL; > > + /* > > + * Make sure merged queues belong to the same parent. Parents could > > + * have changed since the time we decided the two queues are suitable > > + * for merging. > > + */ > > + if (new_bfqq->entity.parent != bfqq->entity.parent) > > + return NULL; > > + > Hi, > > This seems unnecessary, the caller of bfq_setup_merge() aready make sure > bfqq and new_bfqq are under the same bfqg. Am I missing something? Not all the callers of bfq_setup_merge() check that queues belong to the same cgroup (e.g. bfq_setup_cooperator() does not seem to check). Honza > > Thanks, > Kuai > > bfq_log_bfqq(bfqq->bfqd, bfqq, "scheduling merge with queue %d", > > new_bfqq->pid); > > -- Jan Kara <jack@xxxxxxxx> SUSE Labs, CR
