Re: [PATCH 0/8] implement "memmap on memory" feature on s390

[David Hildenbrand]

On 17.11.23 14:56, Sumanth Korikkar wrote:
> On Fri, Nov 17, 2023 at 12:08:31AM +0100, David Hildenbrand wrote:
> > On 14.11.23 19:02, Sumanth Korikkar wrote:
> > > Hi All,
> > >
> > > The patch series implements "memmap on memory" feature on s390 and
> > > provides the necessary fixes for it.
> >
> > Thinking about this, one thing that makes s390x different from all the other
> > architectures in this series is the altmap handling.
> >
> > I'm curious, why is that even required?
> >
> > A memmep that is not marked as online in the section should not be touched
> > by anybody (except memory onlining code :) ). And if we do, it's usually a
> > BUG because that memmap might contain garbage/be poisoned or completely
> > stale, so we might want to track that down and fix it in any case.
> >
> > So what speaks against just leaving add_memory() populate the memmap from
> > the altmap? Then, also the page tables for the memmap are already in place
> > when onlining memory.
>
> we do have page_init_poison() in sparse_add_section() which should be
> handled later then. not in add_pages()

Was that all, or did you stumble over other things?

--
Cheers,

David / dhildenb