On Mon, Jul 17, 2023 at 03:31:08PM +0100, Ryan Roberts wrote: > In preparation for the introduction of large folios for anonymous > memory, we would like to be able to split them when they have unmapped > subpages, in order to free those unused pages under memory pressure. So > remove the artificial requirement that the large folio needed to be at > least PMD-sized. > > Signed-off-by: Ryan Roberts <ryan.roberts@xxxxxxx> > Reviewed-by: Yu Zhao <yuzhao@xxxxxxxxxx> > Reviewed-by: Yin Fengwei <fengwei.yin@xxxxxxxxx> Reviewed-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx> > */ > - if (folio_test_pmd_mappable(folio) && folio_test_anon(folio)) > + if (folio_test_large(folio) && folio_test_anon(folio)) > if (!compound || nr < nr_pmdmapped) > deferred_split_folio(folio); I wonder if it's worth introducing a folio_test_deferred_split() (better naming appreciated ...) to allow us to allocate order-1 folios and not do horrible things. Maybe it's not worth supporting order-1 folios; we're always better off going to order-2 immediately. Just thinking.
