For those of you not subscribed, linux-mm is currently discussing how best to handle page faults on large folios. I simply made it work when adding large folio support. Now Yin Fengwei is working on making it fast. https://lore.kernel.org/linux-mm/Y9qjn0Y+1ir787nc@xxxxxxxxxxxxxxxxxxxx/ is perhaps the best place to start as it pertains to what the architecture will see. At the bottom of that function, I propose + for (i = 0; i < nr; i++) { + set_pte_at(vma->vm_mm, addr, vmf->pte + i, entry); + /* no need to invalidate: a not-present page won't be cached */ + update_mmu_cache(vma, addr, vmf->pte + i); + addr += PAGE_SIZE; + entry = pte_next(entry); + } (or I would have, had I not forgotten that pte_t isn't an integral type) But I think that some architectures want to mark PTEs specially for "This is part of a contiguous range" -- ARM, perhaps? So would you like an API like: arch_set_ptes(mm, addr, vmf->pte, entry, nr); update_mmu_cache_range(vma, addr, vmf->pte, nr); There are some challenges here. For example, folios may be mapped askew (ie not naturally aligned). Another problem is that folios may be unmapped in part (eg mmap(), fault, followed by munmap() of one of the pages in the folio), and I presume you'd need to go and unmark the other PTEs in that case. So it's not as simple as just checking whether 'addr' and 'nr' are in some way compatible.
