Re: [PATCH 03/21] mm/hugetlb: correct demote page offset logic

[Doug Berger]

On 9/14/2022 10:08 AM, Mike Kravetz wrote:
> On 09/13/22 18:07, Doug Berger wrote:
> > On 9/13/2022 4:34 PM, Matthew Wilcox wrote:
> > > On Tue, Sep 13, 2022 at 12:54:50PM -0700, Doug Berger wrote:
> > > > With gigantic pages it may not be true that struct page structures
> > > > are contiguous across the entire gigantic page. The mem_map_offset
> > > > function is used here in place of direct pointer arithmetic to
> > > > correct for this.
> > >
> > > We're just eliminating mem_map_offset().  Please use nth_page()
> > > instead.That's good to know. I will include that in v2.
>
> Thanks Doug and Matthew.  I will take a closer look at this series soon.
>
> It seems like this patch is a fix independent of the series.  If so, I
> would suggest sending separate to make it easy for backports to stable.
Yes, as I noted in [PATCH 00/21] the first three patches fit that 
description, but I included them here in case someone was brave enough 
to attempt to use this patch set. They were in my branch for my own testing.

Full disclosure: An earlier version of this patch set had more complete 
support for hugepage isolation that included migrating the isolation 
state when demoting a hugepage that touched lines in 
demote_free_huge_page() and depended on the subpage variable introduced 
here.

At this point I will submit a patch for this on its own and will likely 
remove the first three commits when submitting V2 of the set.

Thanks for your consideration.
-Doug