On Fri, 2020-02-28 at 09:25 +0100, Vlastimil Babka wrote:
> On 2/28/20 2:21 AM, Rik van Riel wrote:
> > On Thu, 2020-02-27 at 15:41 -0800, Mike Kravetz wrote:
> > > On 2/27/20 1:32 PM, Rik van Riel wrote:
> > > > +++ b/mm/page_alloc.c
> > > > @@ -8253,14 +8253,19 @@ struct page *has_unmovable_pages(struct
> > > > zone *zone, struct page *page,
> > > >
> > > > /*
> > > > * Hugepages are not in LRU lists, but they're
> > > > movable.
> > > > + * THPs are on the LRU, but need to be counted
> > > > as
> > > > #small pages.
> > > > * We need not scan over tail pages because we
> > > > don't
> > > > * handle each tail page individually in
> > > > migration.
> > > > */
> > > > - if (PageHuge(page)) {
> > > > + if (PageHuge(page) || PageTransCompound(page))
> > > > {
> > > > struct page *head =
> > > > compound_head(page);
> > > > unsigned int skip_pages;
> > > >
> > > > - if
> > > > (!hugepage_migration_supported(page_hstate(head)))
> > > > + if (PageHuge(page) &&
> > > > + !hugepage_migration_supported(page_
> > > > hstate(h
> > > > ead)))
> > > > + return page;
> > > > +
> > > > + if (!PageLRU(head) &&
> > > > !__PageMovable(head))
> > >
> > > Pretty sure this is going to be true for hugetlb pages. So, this
> > > will change
> > > behavior and make all hugetlb pages look unmovable. Perhaps,
> > > only
> > > check this
> > > condition for THP pages?
>
> Oh right you are.
>
> > Does that need to be the following, then?
> >
> > if (PageTransHuge(head) && !PageHuge(page) && !PageLRU(head)
> > &&
> > !__PageMovable(head))
> > return page;
>
> I would instead make it an "else if" to the "if (PageHuge(page)...)"
> above.
That was my first thought too, but that could break on
pages that are PageHuge when hugepage_migration_supported
returns true.
--
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