On 7/4/2023 3:05 AM, Yu Zhao wrote: > On Mon, Jul 3, 2023 at 7:53 AM Ryan Roberts <ryan.roberts@xxxxxxx> wrote: >> >> In preparation for FLEXIBLE_THP support, improve >> folio_add_new_anon_rmap() to allow a non-pmd-mappable, large folio to be >> passed to it. In this case, all contained pages are accounted using the >> "small" pages scheme. > > Nit: In this case, all *subpages* are accounted using the *order-0 > folio* (or base page) scheme. Matthew suggested not to use subpage with folio. Using page with folio: https://lore.kernel.org/linux-mm/Y9qiS%2FIxZOMx62t6@xxxxxxxxxxxxxxxxxxxx/ > >> Signed-off-by: Ryan Roberts <ryan.roberts@xxxxxxx> > > Reviewed-by: Yu Zhao <yuzhao@xxxxxxxxxx> > >> mm/rmap.c | 26 +++++++++++++++++++------- >> 1 file changed, 19 insertions(+), 7 deletions(-) >> >> diff --git a/mm/rmap.c b/mm/rmap.c >> index 1d8369549424..82ef5ba363d1 100644 >> --- a/mm/rmap.c >> +++ b/mm/rmap.c >> @@ -1278,31 +1278,43 @@ void page_add_anon_rmap(struct page *page, struct vm_area_struct *vma, >> * This means the inc-and-test can be bypassed. >> * The folio does not have to be locked. >> * >> - * If the folio is large, it is accounted as a THP. As the folio >> + * If the folio is pmd-mappable, it is accounted as a THP. As the folio >> * is new, it's assumed to be mapped exclusively by a single process. >> */ >> void folio_add_new_anon_rmap(struct folio *folio, struct vm_area_struct *vma, >> unsigned long address) >> { >> - int nr; >> + int nr = folio_nr_pages(folio); >> + int i; >> + struct page *page; >> >> - VM_BUG_ON_VMA(address < vma->vm_start || address >= vma->vm_end, vma); >> + VM_BUG_ON_VMA(address < vma->vm_start || >> + address + (nr << PAGE_SHIFT) > vma->vm_end, vma); >> __folio_set_swapbacked(folio); >> >> - if (likely(!folio_test_pmd_mappable(folio))) { >> + if (!folio_test_large(folio)) { >> /* increment count (starts at -1) */ >> atomic_set(&folio->_mapcount, 0); >> - nr = 1; >> + __page_set_anon_rmap(folio, &folio->page, vma, address, 1); >> + } else if (!folio_test_pmd_mappable(folio)) { >> + /* increment count (starts at 0) */ >> + atomic_set(&folio->_nr_pages_mapped, nr); >> + >> + page = &folio->page; >> + for (i = 0; i < nr; i++, page++, address += PAGE_SIZE) { >> + /* increment count (starts at -1) */ >> + atomic_set(&page->_mapcount, 0); >> + __page_set_anon_rmap(folio, page, vma, address, 1); >> + } > > Nit: use folio_page(), e.g., > > } else if (!folio_test_pmd_mappable(folio)) { > int i; > > for (i = 0; i < nr; i++) { > struct page *page = folio_page(folio, i); > > /* increment count (starts at -1) */ > atomic_set(&page->_mapcount, 0); > __page_set_anon_rmap(folio, page, vma, address + PAGE_SIZE * i, 1); > } > /* increment count (starts at 0) */ > atomic_set(&folio->_nr_pages_mapped, nr); > } else { > >> } else { >> /* increment count (starts at -1) */ >> atomic_set(&folio->_entire_mapcount, 0); >> atomic_set(&folio->_nr_pages_mapped, COMPOUND_MAPPED); >> - nr = folio_nr_pages(folio); >> __lruvec_stat_mod_folio(folio, NR_ANON_THPS, nr); >> + __page_set_anon_rmap(folio, &folio->page, vma, address, 1); >> } >> >> __lruvec_stat_mod_folio(folio, NR_ANON_MAPPED, nr); >> - __page_set_anon_rmap(folio, &folio->page, vma, address, 1); >> }
