On Fri, Sep 13, 2019 at 2:18 AM Kirill A. Shutemov <[email protected]> wrote: > > Adding fully unmapped pages into deferred split queue is not productive: > these pages are about to be freed or they are pinned and cannot be split > anyway.
This change looks good to me. Reviewed-by: Yang Shi <[email protected]> > > Signed-off-by: Kirill A. Shutemov <[email protected]> > --- > mm/rmap.c | 14 ++++++++++---- > 1 file changed, 10 insertions(+), 4 deletions(-) > > diff --git a/mm/rmap.c b/mm/rmap.c > index 003377e24232..45388f1bf317 100644 > --- a/mm/rmap.c > +++ b/mm/rmap.c > @@ -1271,12 +1271,20 @@ static void page_remove_anon_compound_rmap(struct > page *page) > if (TestClearPageDoubleMap(page)) { > /* > * Subpages can be mapped with PTEs too. Check how many of > - * themi are still mapped. > + * them are still mapped. > */ > for (i = 0, nr = 0; i < HPAGE_PMD_NR; i++) { > if (atomic_add_negative(-1, &page[i]._mapcount)) > nr++; > } > + > + /* > + * Queue the page for deferred split if at least one small > + * page of the compound page is unmapped, but at least one > + * small page is still mapped. > + */ > + if (nr && nr < HPAGE_PMD_NR) > + deferred_split_huge_page(page); > } else { > nr = HPAGE_PMD_NR; > } > @@ -1284,10 +1292,8 @@ static void page_remove_anon_compound_rmap(struct page > *page) > if (unlikely(PageMlocked(page))) > clear_page_mlock(page); > > - if (nr) { > + if (nr) > __mod_node_page_state(page_pgdat(page), NR_ANON_MAPPED, -nr); > - deferred_split_huge_page(page); > - } > } > > /** > -- > 2.21.0 > >
