我是 Linux 内核编程新手。我正在为 Linux kernel-6.0 编写一个内核模块
这是下面的代码
static int count_wired_pages(unsigned long start_pfn, unsigned long end_pfn)
{
unsigned long pfn;
int nr_pages=0, page_mt, count = 0;
struct page *page;
struct page_ext *page_ext;
struct page_owner *page_owner;
for (pfn = start_pfn; pfn < end_pfn; pfn++) {
if (!pfn_valid(pfn))
continue;
/*some code*/
page = pfn_to_page(pfn);
page_ext = lookup_page_ext(page);
if (unlikely(!page_ext))
continue;
if (!test_bit(PAGE_EXT_OWNER_ALLOCATED, &page_ext->flags))
continue;
page_owner = get_page_owner(page_ext);
page_mt = gfp_migratetype(page_owner->gfp_mask);
nr_pages = (1UL << page_owner->order);
/*some code*/
}
在上面的代码中,我正在调用该函数lookup_page_ext()
。在内核.config
文件中,我启用了CONFIG_PAGE_EXTENSION
和CONFIG_PAGE_OWNER
。另外,我还添加了EXPORT_SYMBOL
函数lookup_page_ext()
,以便它对我的模块可见。
尽管完成了所有这些操作,该函数还是返回了NULL
。我有什么遗漏的吗?