On 04/02/2018 10:56 AM, Linus Torvalds wrote: > On Mon, Apr 2, 2018 at 10:27 AM, Dave Hansen > <dave.hansen@xxxxxxxxxxxxxxx> wrote: >> + /* >> + * The cpu_entry_area is shared between the user and kernel >> + * page tables. All of its ptes can safely be global. >> + */ >> + if (boot_cpu_has(X86_FEATURE_PGE)) >> + pte = pte_set_flags(pte, _PAGE_GLOBAL); > So this is where the quesion of "why is this conditional" is valid. > > We could set _PAGE_GLOBAL unconditionally, not bothering with testing > X86_FEATURE_PGE. I think we should just keep the check for now. Before this patch set, on !X86_FEATURE_PGE systems, we cleared _PAGE_GLOBAL in virtually all places due to masking via __supported_pte_mask. It is rather harmless either way, but being _consistent_ (by keeping the check) with all of our PTEs is nice.
