问如何在使用内核Linux (6)源代码访问交换空间时插入延迟？

EN

        if (!folio) {
            /*
             * Back out if somebody else faulted in this pte
             * while we released the pte lock.
             */
            vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd,
                    vmf->address, &vmf->ptl);
            if (likely(pte_same(*vmf->pte, vmf->orig_pte)))
                ret = VM_FAULT_OOM;
            goto unlock;
        }

        /* Had to read the page from swap area: Major fault */
        ret = VM_FAULT_MAJOR;
        count_vm_event(PGMAJFAULT);
        count_memcg_event_mm(vma->vm_mm, PGMAJFAULT);