/* * split_page takes a non-compound higher-order page, and splits it into * n (1<<order) sub-pages: page[0..n] * Each sub-page must be freed individually. * * Note: this is probably too low level an operation for use in drivers. * Please consult with lkml before using this in your driver. */ void split_page(struct page *page, unsigned int order) { int i; VM_BUG_ON(PageCompound(page)); VM_BUG_ON(!page_count(page)); #ifdef CONFIG_KMEMCHECK /* * Split shadow pages too, because free(page[0]) would * otherwise free the whole shadow. */ if (kmemcheck_page_is_tracked(page)) split_page(virt_to_page(page[0].shadow), order); #endif for (i = 1; i < (1 << order); i++) set_page_refcounted(page + i); }
void kmemcheck_free_shadow(struct page *page, int order) { struct page *shadow; int pages; int i; if (!kmemcheck_page_is_tracked(page)) return; pages = 1 << order; kmemcheck_show_pages(page, pages); shadow = virt_to_page(page[0].shadow); for(i = 0; i < pages; ++i) page[i].shadow = NULL; __free_pages(shadow, order); }