From c5c540034747dfe450f64d1151081a6080daa8f9 Mon Sep 17 00:00:00 2001 From: David Hildenbrand Date: Wed, 13 Sep 2023 14:51:10 +0200 Subject: mm/rmap: move folio_test_anon() check out of __folio_set_anon() Let's handle it in the caller; no need for the "first" check based on the mapcount. We really only end up with !anon pages in page_add_anon_rmap() via do_swap_page(), where we hold the folio lock. So races are not possible. Add a VM_WARN_ON_FOLIO() to make sure that we really hold the folio lock. In the future, we might want to let do_swap_page() use folio_add_new_anon_rmap() on new pages instead: however, we might have to pass then whether the folio is exclusive or not. So keep it in there for now. For hugetlb we never expect to have a non-anon page in hugepage_add_anon_rmap(). Remove that code, along with some other checks that are either not required or were checked in hugepage_add_new_anon_rmap() already. Link: https://lkml.kernel.org/r/20230913125113.313322-4-david@redhat.com Signed-off-by: David Hildenbrand Cc: Matthew Wilcox Cc: Mike Kravetz Cc: Muchun Song Signed-off-by: Andrew Morton --- mm/rmap.c | 23 ++++++++--------------- 1 file changed, 8 insertions(+), 15 deletions(-) (limited to 'mm/rmap.c') diff --git a/mm/rmap.c b/mm/rmap.c index f76f0f23725c..65de3832123e 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -1135,9 +1135,6 @@ static void __folio_set_anon(struct folio *folio, struct vm_area_struct *vma, BUG_ON(!anon_vma); - if (folio_test_anon(folio)) - return; - /* * If the folio isn't exclusive to this vma, we must use the _oldest_ * possible anon_vma for the folio mapping! @@ -1239,12 +1236,12 @@ void page_add_anon_rmap(struct page *page, struct vm_area_struct *vma, if (nr) __lruvec_stat_mod_folio(folio, NR_ANON_MAPPED, nr); - if (likely(!folio_test_ksm(folio))) { - if (first) - __folio_set_anon(folio, vma, address, - !!(flags & RMAP_EXCLUSIVE)); - else - __page_check_anon_rmap(folio, page, vma, address); + if (unlikely(!folio_test_anon(folio))) { + VM_WARN_ON_FOLIO(!folio_test_locked(folio), folio); + __folio_set_anon(folio, vma, address, + !!(flags & RMAP_EXCLUSIVE)); + } else if (likely(!folio_test_ksm(folio))) { + __page_check_anon_rmap(folio, page, vma, address); } if (flags & RMAP_EXCLUSIVE) SetPageAnonExclusive(page); @@ -2541,17 +2538,13 @@ void hugepage_add_anon_rmap(struct page *page, struct vm_area_struct *vma, unsigned long address, rmap_t flags) { struct folio *folio = page_folio(page); - struct anon_vma *anon_vma = vma->anon_vma; int first; - BUG_ON(!folio_test_locked(folio)); - BUG_ON(!anon_vma); + VM_WARN_ON_FOLIO(!folio_test_anon(folio), folio); + first = atomic_inc_and_test(&folio->_entire_mapcount); VM_BUG_ON_PAGE(!first && (flags & RMAP_EXCLUSIVE), page); VM_BUG_ON_PAGE(!first && PageAnonExclusive(page), page); - if (first) - __folio_set_anon(folio, vma, address, - !!(flags & RMAP_EXCLUSIVE)); if (flags & RMAP_EXCLUSIVE) SetPageAnonExclusive(page); } -- cgit v1.2.3