On Tue, Nov 18, 2025 at 06:11:24PM +0100, Pratyush Yadav wrote: > On Tue, Nov 18 2025, Pasha Tatashin wrote: > > >> > This page is never freed, so adding it to zone managed pages or keeping > >> > it > >> > reserved does not change anything. > >> > >> In practice, sure. I still don't see a good reason to _not_ initialize > >> the page properly. It's not like it costs us much in terms of > >> performance or code complexity. > >> > >> Since kho_restore_folio() makes sure the folio was _actually_ preserved > >> from KHO, you have a safety check against previous kernel having a bug > >> and not preserving the FDT properly. And I get that the FDT has already > >> been used by this point, but at least you would have some known point to > >> catch this. > > > > The kho_alloc_preserve() API is different from kho_preserve_folio(). > > With kho_preserve_folio(), memory is allocated and some time later is > > preserved, so there is a possibility for that memory to exist and be > > used where it is not preserved, therefore it is a crucial step for > > such memory to also do kho_restore_folio() before used. With > > kho_alloc_preserve(), when the memory exists it is always preserved; > > it is gurantee of this API. There is no reason to do > > kho_restore_folio() on such memory at all. It can be released back to > > the system via kho_free_restore()/kho_free_unpreserve(). > > Even for those I think there should be a kho_restore_mem() or something > similar (naming things is hard :/), so they go through the restore, > their struct page is properly initialized and accounted for, and > make sure the pages were actually preserved. > > Using the memory without restoring it first should be the exception IMO. Base KHO and LUO FTDs are such exceptions for sure :) We have to use them way before we can even think about restoring.
> -- > Regards, > Pratyush Yadav -- Sincerely yours, Mike.
