Messages in this thread | | | Date | Wed, 6 Jan 2021 17:11:35 +0100 | From | Michal Hocko <> | Subject | Re: [PATCH 1/6] mm: migrate: do not migrate HugeTLB page whose refcount is one |
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On Mon 04-01-21 14:58:38, Muchun Song wrote: > If the refcount is one when it is migrated, it means that the page > was freed from under us. So we are done and do not need to migrate.
Is this common enough that it would warrant the explicit check for each migration?
> Signed-off-by: Muchun Song <songmuchun@bytedance.com> > --- > mm/migrate.c | 6 ++++++ > 1 file changed, 6 insertions(+) > > diff --git a/mm/migrate.c b/mm/migrate.c > index 4385f2fb5d18..a6631c4eb6a6 100644 > --- a/mm/migrate.c > +++ b/mm/migrate.c > @@ -1279,6 +1279,12 @@ static int unmap_and_move_huge_page(new_page_t get_new_page, > return -ENOSYS; > } > > + if (page_count(hpage) == 1) { > + /* page was freed from under us. So we are done. */ > + putback_active_hugepage(hpage); > + return MIGRATEPAGE_SUCCESS; > + } > + > new_hpage = get_new_page(hpage, private); > if (!new_hpage) > return -ENOMEM; > -- > 2.11.0
-- Michal Hocko SUSE Labs
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