Re: [PATCH v15 06/26] x86/mm: Change _PAGE_DIRTY to _PAGE_DIRTY_HW

From: Yu, Yu-cheng
Date: Thu Dec 03 2020 - 10:57:38 EST


On 12/3/2020 7:12 AM, Dave Hansen wrote:
On 12/3/20 1:19 AM, Borislav Petkov wrote:
On Tue, Nov 10, 2020 at 08:21:51AM -0800, Yu-cheng Yu wrote:
Before introducing _PAGE_COW for non-hardware memory management purposes in
the next patch, rename _PAGE_DIRTY to _PAGE_DIRTY_HW and _PAGE_BIT_DIRTY to
_PAGE_BIT_DIRTY_HW to make meanings more clear. There are no functional
changes from this patch.
There's no guarantee for "next" or "this" patch when a patch gets
applied so reword your commit message pls.

Also, I fail to understand here what _PAGE_DIRTY_HW makes more clear?
The page dirty bit is clear enough to me so why the churn?

Once upon a time in this set, we had:

_PAGE_DIRTY (the old hardware bit)
and
_PAGE_DIRTY_SW (the new shadow stack necessitated bit)

In *that* case, it made sense to change the name of the hardware one to
help differentiate them. But, over time, we changed _PAGE_DIRTY_SW to
_PAGE_COW.

I think you're right. The renaming is just churn now with the current
naming.


Ok, I will drop this patch.