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You should not > break the documented behavior without verifying that no caller is relying > on the current behavior. If this is fine, please update the comment. This brings up a point from my other reply. The comment says that it returns "the effective NX and RW bits of all page table levels", but in fact NX and RW are not updated for the PTE. Since the comment says all page table levels, shouldn't they be updated with the PTE values, too? Thanks, Tom > > > Juergen > >> >> Signed-off-by: Ashish Kalra >> --- >>   arch/x86/mm/pat/set_memory.c | 7 ++++++- >>   1 file changed, 6 insertions(+), 1 deletion(-) >> >> diff --git a/arch/x86/mm/pat/set_memory.c b/arch/x86/mm/pat/set_memory.c >> index 443a97e515c0..be8b5bf3bc3f 100644 >> --- a/arch/x86/mm/pat/set_memory.c >> +++ b/arch/x86/mm/pat/set_memory.c >> @@ -672,6 +672,7 @@ pte_t *lookup_address_in_pgd_attr(pgd_t *pgd, >> unsigned long address, >>       p4d_t *p4d; >>       pud_t *pud; >>       pmd_t *pmd; >> +    pte_t *pte; >>         *level = PG_LEVEL_256T; >>       *nx = false; >> @@ -717,7 +718,11 @@ pte_t *lookup_address_in_pgd_attr(pgd_t *pgd, >> unsigned long address, >>       *nx |= pmd_flags(*pmd) & _PAGE_NX; >>       *rw &= pmd_flags(*pmd) & _PAGE_RW; >>   -    return pte_offset_kernel(pmd, address); >> +    pte = pte_offset_kernel(pmd, address); >> +    if (pte_none(*pte)) >> +        return NULL; >> + >> +    return pte; >>   } >>     /* >