Re: [PATCH] mm: Mark idle page tracking as BROKEN

[Matthew Wilcox <willy@infradead.org>]

On Tue, Jun 15, 2021 at 09:41:37AM +0200, David Hildenbrand wrote:
> On 12.06.21 02:07, Matthew Wilcox (Oracle) wrote:
> 
> I might be missing something important, so some questions/comments
> 
> > In discussion with other MM developers around how idle page tracking
> > should be fixed for transparent huge pages, several expressed the opinion
> > that it should be removed as it is inefficient at accomplishing the
> > job that it is supposed to, and we have better mechanisms (eg uffd) for
> > accomplishing the same goals these days.
> 
> 1. A link to that discussion would be nice. I am missing some important
> details in this patch description.

It was on the phone in our bi-weekly THP call.  As I recall, those
present were Kirill, Yu Zhao, William Kucharski, Zi Yan, Vlastimil Babka.
Song Liu sent apologies, and I think Mike Kravetz had a conflict.

> 2. "should be fixed for transparent huge pages" -- has it always been like
> this or has the behavior changed at some point? Do the semantics, and how
> the feature is getting used, clearly identify this case that needs fixing as
> something that really has to be fixed? Or was it always like that and
> actually expected to work like that ("semtantics")?

I don't know.  I asked the others on the call and the answer I got was
essentially "Just delete it".

I'm kind of hoping the others speak up.