[go源码]请教GMP模型中工作窃取work steal的并发冲突问题

1. go版本1.19.2

2. 源码 runtime.runqgrab

func runqgrab(_p_ *p, batch *[256]guintptr, batchHead uint32, stealRunNextG bool) uint32 {
    for {
        h := atomic.LoadAcq(&_p_.runqhead) // load-acquire, synchronize with other consumers
        t := atomic.LoadAcq(&_p_.runqtail) // load-acquire, synchronize with the producer
        n := t - h
        n = n - n/2
        if n == 0 {
            if stealRunNextG {
                // Try to steal from _p_.runnext.
                if next := _p_.runnext; next != 0 {
                    if _p_.status == _Prunning {
                        if GOOS != "windows" && GOOS != "openbsd" && GOOS != "netbsd" {
                            usleep(3)
                        } else {
                            osyield()
                        }
                    }
                    if !_p_.runnext.cas(next, 0) {
                        continue
                    }
                    batch[batchHead%uint32(len(batch))] = next
                    return 1
                }
            }
            return 0
        }
        if n > uint32(len(_p_.runq)/2) { // read inconsistent h and t
            continue
        }
        for i := uint32(0); i < n; i++ {
            g := _p_.runq[(h+i)%uint32(len(_p_.runq))]
            batch[(batchHead+i)%uint32(len(batch))] = g
        }
        if atomic.CasRel(&_p_.runqhead, h, h+n) { // cas-release, commits consume
            return n
        }
    }
}

3. 疑问

 for i := uint32(0); i < n; i++ {
            g := _p_.runq[(h+i)%uint32(len(_p_.runq))]
            batch[(batchHead+i)%uint32(len(batch))] = g
        }

这部分代码已经将待偷取的p中的g传给batch了，如果后面并发问题cas失败的话，batch中已经存在的g是怎么处理的？怎么做到的偷取失败的g不会被重复执行？