From: David Hildenbrand david@redhat.com
mainline inclusion from mainline-6.7-rc1 commit c5c540034747dfe450f64d1151081a6080daa8f9 category: feature bugzilla: https://gitee.com/openeuler/kernel/issues/I98AW9 CVE: NA
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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 david@redhat.com Cc: Matthew Wilcox willy@infradead.org Cc: Mike Kravetz mike.kravetz@oracle.com Cc: Muchun Song muchun.song@linux.dev Signed-off-by: Andrew Morton akpm@linux-foundation.org (cherry picked from commit c5c540034747dfe450f64d1151081a6080daa8f9) Signed-off-by: Kefeng Wang wangkefeng.wang@huawei.com --- mm/rmap.c | 23 ++++++++--------------- 1 file changed, 8 insertions(+), 15 deletions(-)
diff --git a/mm/rmap.c b/mm/rmap.c index 2e732ea8d6ce..56fac8547afc 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -1169,9 +1169,6 @@ 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! @@ -1273,12 +1270,12 @@ 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); @@ -2592,17 +2589,13 @@ 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); }