Re: [PATCH v2 02/34] s390: Use _pt_s390_gaddr for gmap address tracking

[Vishal Moola <vishal.moola@xxxxxxxxx>]

On Thu, May 25, 2023 at 1:58 AM Mike Rapoport <rppt@xxxxxxxxxx> wrote:
>
> On Mon, May 01, 2023 at 12:27:57PM -0700, Vishal Moola (Oracle) wrote:
> > s390 uses page->index to keep track of page tables for the guest address
> > space. In an attempt to consolidate the usage of page fields in s390,
> > replace _pt_pad_2 with _pt_s390_gaddr to replace page->index in gmap.
> >
> > This will help with the splitting of struct ptdesc from struct page, as
> > well as allow s390 to use _pt_frag_refcount for fragmented page table
> > tracking.
> >
> > Since page->_pt_s390_gaddr aliases with mapping, ensure its set to NULL
> > before freeing the pages as well.
>
> Wouldn't it be easier to use _pt_pad_1 which is aliased with lru and that
> does not seem to be used by page tables at all?

I initially thought the same, but s390 page tables use lru.