[PATCH RFC 07/13] mm/rmap: use page_move_anon_rmap() when reusing a mapped PageAnon() page exclusively

David Hildenbrand
2022-02-24T12:31:10Z

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.

Signed-off-by: David Hildenbrand <david@redhat.com>
---
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 2ca137e01e84..7b9e76ba3f2f 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 c2f1c2428303..1ab0dfbec288 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -3307,6 +3307,7 @@ 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;
--
2.35.1