On 04/07/2023 03:13, Yin, Fengwei wrote: > > > 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/ OK, I'll change this to "In this case, all contained pages are accounted using the *order-0 folio* (or base page) scheme." > >> >>> Signed-off-by: Ryan Roberts <ryan.roberts@xxxxxxx> >> >> Reviewed-by: Yu Zhao <yuzhao@xxxxxxxxxx> Thanks! >> >>> 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., Yep, will change for v3. >> >> } 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); >>> }
