On 08/11/2017 08:56, Haozhong Zhang wrote: > +bool pat_pfn_is_uc_or_uc_minus(unsigned long pfn) > +{ > + enum page_cache_mode cm = lookup_memtype(PFN_PHYS(pfn)); > + > + return cm == _PAGE_CACHE_MODE_UC || cm == _PAGE_CACHE_MODE_UC_MINUS; > +} > +EXPORT_SYMBOL_GPL(pat_pfn_is_uc_or_uc_minus); > + As discussed in the reply to v2, this should include WC too. The function name could become something like pat_pfn_downgraded_by_uc_mtrr. Thanks, Paolo