On Tue, 21 Aug 2018, Bin Yang wrote: > @@ -625,6 +625,7 @@ try_preserve_large_page(pte_t *kpte, unsigned long > address, > > psize = page_level_size(level); > pmask = page_level_mask(level); > + addr = address & pmask; > > /* > * Calculate the number of pages, which fit into this large > @@ -636,6 +637,12 @@ try_preserve_large_page(pte_t *kpte, unsigned long > address, > cpa->numpages = numpages; > > /* > + * The old pgprot should not have any protection bit. Otherwise, > + * the existing mapping is wrong already. > + */ > + WARN_ON_ONCE(needs_static_protections(old_prot, addr, psize, old_pfn));
The check itself is fine, but it just emits a warning and goes on as if nothing happened. We really want to think about a proper way to fix that up without overhead for the sane case. Thanks, tglx