Re: [PATCHv3, RFC 32/34] thp: handle write-protect exception tofile-backed huge pages

[Kirill A. Shutemov]

Dave Hansen wrote:
> > +			if (!PageAnon(page)) {
> > +				add_mm_counter(mm, MM_FILEPAGES, -HPAGE_PMD_NR);
> > +				add_mm_counter(mm, MM_ANONPAGES, HPAGE_PMD_NR);
> > +			}
> 
> This seems like a bit of a hack.  Shouldn't we have just been accounting
> to MM_FILEPAGES in the first place?

No, it's not.

It handles MAP_PRIVATE file mappings. The page was read first and
accounted to MM_FILEPAGES and then COW'ed by anon page here, so we have to
adjust counters. do_wp_page() has similar code.

-- 
 Kirill A. Shutemov
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