On 09/03/2020 11:01 PM, Ralph Campbell wrote: > > On 9/3/20 9:56 AM, Catalin Marinas wrote: >> On Mon, Aug 17, 2020 at 02:49:43PM +0530, Anshuman Khandual wrote: >>> pmd_present() and pmd_trans_huge() are expected to behave in the following >>> manner during various phases of a given PMD. It is derived from a previous >>> detailed discussion on this topic [1] and present THP documentation [2]. >>> >>> pmd_present(pmd): >>> >>> - Returns true if pmd refers to system RAM with a valid pmd_page(pmd) >>> - Returns false if pmd does not refer to system RAM - Invalid pmd_page(pmd) >> >> The second bullet doesn't make much sense. If you have a pmd mapping of >> some I/O memory, pmd_present() still returns true (as does >> pte_present()). >> >>> diff --git a/arch/arm64/include/asm/pgtable-prot.h b/arch/arm64/include/asm/pgtable-prot.h >>> index 4d867c6446c4..28792fdd9627 100644 >>> --- a/arch/arm64/include/asm/pgtable-prot.h >>> +++ b/arch/arm64/include/asm/pgtable-prot.h >>> @@ -19,6 +19,13 @@ >>> #define PTE_DEVMAP (_AT(pteval_t, 1) << 57) >>> #define PTE_PROT_NONE (_AT(pteval_t, 1) << 58) /* only when !PTE_VALID */ >>> +/* >>> + * This help indicate that the entry is present i.e pmd_page() >> >> Nit: add another . after i.e > > Another nit: "This help indicate" => "This helper indicates" > > Maybe I should look at the series more. :-) It is talking about the new PTE bit being used here not any helper. Though the following replacement might be better. s/This help indicate/This bit indicates/ /* * This help indicate that the entry is present i.e pmd_page() * still points to a valid huge page in memory even if the pmd * has been invalidated. */ #define PMD_PRESENT_INVALID (_AT(pteval_t, 1) << 59) /* only when !PMD_SECT_VALID */
