From 6c54dc6c74371eebf7eddc16b4f64b8c841c1585 Mon Sep 17 00:00:00 2001 From: David Hildenbrand Date: Mon, 9 May 2022 18:20:43 -0700 Subject: [PATCH] mm/rmap: use page_move_anon_rmap() when reusing a mapped PageAnon() page exclusively We want to mark anonymous pages exclusive, and when using page_move_anon_rmap() we know that we are the exclusive user, as properly documented. This is a preparation for marking anonymous pages exclusive in page_move_anon_rmap(). In both instances, we're holding page lock and are sure that we're the exclusive owner (page_count() == 1). hugetlb already properly uses page_move_anon_rmap() in the write fault handler. Note that in case of a PTE-mapped THP, we'll only end up calling this function if the whole THP is only referenced by the single PTE mapping a single subpage (page_count() == 1); consequently, it's fine to modify the compound page mapping inside page_move_anon_rmap(). Link: https://lkml.kernel.org/r/20220428083441.37290-10-david@redhat.com Signed-off-by: David Hildenbrand Acked-by: Vlastimil Babka Cc: Andrea Arcangeli Cc: Christoph Hellwig Cc: David Rientjes Cc: Don Dutile Cc: Hugh Dickins Cc: Jan Kara Cc: Jann Horn Cc: Jason Gunthorpe Cc: John Hubbard Cc: Khalid Aziz Cc: "Kirill A. Shutemov" Cc: Liang Zhang Cc: "Matthew Wilcox (Oracle)" Cc: Michal Hocko Cc: Mike Kravetz Cc: Mike Rapoport Cc: Nadav Amit Cc: Oded Gabbay Cc: Oleg Nesterov Cc: Pedro Demarchi Gomes Cc: Peter Xu Cc: Rik van Riel Cc: Roman Gushchin Cc: Shakeel Butt Cc: Yang Shi Signed-off-by: Andrew Morton --- mm/huge_memory.c | 2 ++ mm/memory.c | 1 + 2 files changed, 3 insertions(+) diff --git a/mm/huge_memory.c b/mm/huge_memory.c index c036528..04c9446 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -1317,6 +1317,8 @@ vm_fault_t do_huge_pmd_wp_page(struct vm_fault *vmf) try_to_free_swap(page); if (page_count(page) == 1) { pmd_t entry; + + page_move_anon_rmap(page, vma); entry = pmd_mkyoung(orig_pmd); entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); if (pmdp_set_access_flags(vma, haddr, vmf->pmd, entry, 1)) diff --git a/mm/memory.c b/mm/memory.c index 3dedb57..d4dba17 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -3303,6 +3303,7 @@ static vm_fault_t do_wp_page(struct vm_fault *vmf) * and the page is locked, it's dark out, and we're wearing * sunglasses. Hit it. */ + page_move_anon_rmap(page, vma); unlock_page(page); wp_page_reuse(vmf); return VM_FAULT_WRITE; -- 2.7.4