Re: [PATCH v3 2/2] kho: Introduce preserve/restore APIs for high-order pages

[Pranjal Shrivastava]

On Thu, Jul 30, 2026 at 10:26:41AM +0300, Mike Rapoport wrote:
> Hi Pranjal,
> 
> > The current KHO page preservation APIs (e.g. kho_preserve_pages) assume
> > that multi-page blocks are split into independent 4KB pages during
> > restoration. This is incompatible with high-order non-compound pages,
> > such as DMA buffers, which must be restored with tail pages having a
> > zero reference count.
> > 
> > Introduce explicit preserve and restore APIs for high-order pages,
> > which preserve and restore a high-order page block as a single unit,
> > applying a refcount of 1 to the head page while leaving tail pages at 0.
> > Rename the existing internal helper to __kho_restore_page() and
> > consolidate the common restoration code into it.
> > 
> > Signed-off-by: Pranjal Shrivastava <praan@xxxxxxxxxx>
> >
> > @@ -457,10 +482,14 @@ struct page *kho_restore_pages(phys_addr_t phys, unsigned long nr_pages)
> >  	while (pfn < end_pfn) {
> >  		const unsigned int order =
> >  			min(count_trailing_zeros(pfn), ilog2(end_pfn - pfn));
> > -		struct page *page = kho_restore_page(PFN_PHYS(pfn), false);
> > +		unsigned int info_order;
> > +		struct page *page = __kho_restore_page(PFN_PHYS(pfn), &info_order);
> >  
> >  		if (!page)
> >  			return NULL;
> > +
> > +		kho_init_pages(page, 1UL << info_order);
> > +		adjust_managed_page_count(page, 1UL << info_order);
> 
> Seeing 
> 
> +		adjust_managed_page_count(page, 1UL << info_order);
> 
> for the third time hinted that something is off ;-)
> 

Ack. I'll fold it into the __kho_restore_page() helper 

Thanks,
Praan