On 17/07/2023 16:42, David Hildenbrand wrote: > On 17.07.23 16:31, 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> >> --- >> mm/rmap.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/mm/rmap.c b/mm/rmap.c >> index 0c0d8857dfce..2baf57d65c23 100644 >> --- a/mm/rmap.c >> +++ b/mm/rmap.c >> @@ -1430,7 +1430,7 @@ void page_remove_rmap(struct page *page, struct >> vm_area_struct *vma, >> * page of the folio is unmapped and at least one page >> * is still mapped. >> */ >> - 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); > > !compound will always be true I guess, so nr_pmdmapped == 0 (which will always > be the case) will be ignored. I don't follow why !compound will always be true. This function is page_remove_rmap() (not folio_remove_rmap_range() which I add in a later patch). page_remove_rmap() can work on pmd-mapped pages where compound=true is passed in. > > Reviewed-by: David Hildenbrand <david@xxxxxxxxxx> >
