/*
* 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);
}
