Module demand_paging 

Demand Paging and Copy-on-Write (COW) Manager

Provides infrastructure for lazy page allocation and COW fork support.

Demand Paging

Pages can be registered as “lazy” mappings via register_lazy. When a page fault hits a lazy-mapped address, the manager allocates a physical frame and returns it (along with the appropriate flags) so the caller can install the mapping in the page table.

Copy-on-Write

CowTable tracks shared physical frames with reference counts. When a COW page is written, the fault handler calls DemandPagingManager::handle_cow_fault to allocate a private copy and decrement the shared reference count.

Structs

CowEntry

A single COW-shared physical frame.

CowTable

Table of COW-shared frames keyed by virtual page address.

DemandPagingManager

Manages lazy mappings and COW state.

LazyMapping

A region of virtual address space registered for demand paging.

Enums

BackingType

How a lazy page is backed when finally faulted in.

Functions

handle_page_fault

Try to resolve a page fault via demand paging.

init

Initialize the global demand paging manager.

register_lazy

Register a lazy mapping via the global manager.

with_manager_mut

Access the global demand paging manager (mutable).