On Wed, Sep 10, 2025 at 05:34:40PM +0200, Pratyush Yadav wrote:
> +#define KHO_PAGE_MAGIC 0x4b484f50U /* ASCII for 'KHOP' */
> +
> +/*
> + * KHO uses page->private, which is an unsigned long, to store page metadata.
> + * Use it to store both the magic and the order.
> + */
> +union kho_page_info {
> + unsigned long page_private;
> + struct {
> + unsigned int order;
> + unsigned int magic;
> + };
KHO is only supported on 64-bit?
> @@ -210,16 +226,16 @@ static void kho_restore_page(struct page *page,
> unsigned int order)
> struct folio *kho_restore_folio(phys_addr_t phys)
> {
> struct page *page = pfn_to_online_page(PHYS_PFN(phys));
> - unsigned long order;
> + union kho_page_info info;
>
> if (!page)
> return NULL;
>
> - order = page->private;
> - if (order > MAX_PAGE_ORDER)
> + info.page_private = page->private;
> + if (info.magic != KHO_PAGE_MAGIC || info.order > MAX_PAGE_ORDER)
> return NULL;
>
> - kho_restore_page(page, order);
> + kho_restore_page(page, info.order);
> return page_folio(page);
This all looks very confused. Before your patch as well as after it.
I don't see anything in the current KHO code that requires the
phys_addr_t to be order-aligned.
