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-rw-r--r--include/linux/rmap.h1
-rw-r--r--mm/memory.c7
-rw-r--r--mm/rmap.c24
3 files changed, 32 insertions, 0 deletions
diff --git a/include/linux/rmap.h b/include/linux/rmap.h
index 62da2001d55c..72be23b1480a 100644
--- a/include/linux/rmap.h
+++ b/include/linux/rmap.h
@@ -125,6 +125,7 @@ static inline void anon_vma_merge(struct vm_area_struct *vma,
/*
* rmap interfaces called when adding or removing pte of page
*/
+void page_move_anon_rmap(struct page *, struct vm_area_struct *, unsigned long);
void page_add_anon_rmap(struct page *, struct vm_area_struct *, unsigned long);
void page_add_new_anon_rmap(struct page *, struct vm_area_struct *, unsigned long);
void page_add_file_rmap(struct page *);
diff --git a/mm/memory.c b/mm/memory.c
index dc785b438d70..d1153e37e9ba 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -2138,6 +2138,13 @@ static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
page_cache_release(old_page);
}
reuse = reuse_swap_page(old_page);
+ if (reuse)
+ /*
+ * The page is all ours. Move it to our anon_vma so
+ * the rmap code will not search our parent or siblings.
+ * Protected against the rmap code by the page lock.
+ */
+ page_move_anon_rmap(old_page, vma, address);
unlock_page(old_page);
} else if (unlikely((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
(VM_WRITE|VM_SHARED))) {
diff --git a/mm/rmap.c b/mm/rmap.c
index 23ecd0a892df..28bcdc433d88 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -716,6 +716,30 @@ int page_mkclean(struct page *page)
EXPORT_SYMBOL_GPL(page_mkclean);
/**
+ * page_move_anon_rmap - move a page to our anon_vma
+ * @page: the page to move to our anon_vma
+ * @vma: the vma the page belongs to
+ * @address: the user virtual address mapped
+ *
+ * When a page belongs exclusively to one process after a COW event,
+ * that page can be moved into the anon_vma that belongs to just that
+ * process, so the rmap code will not search the parent or sibling
+ * processes.
+ */
+void page_move_anon_rmap(struct page *page,
+ struct vm_area_struct *vma, unsigned long address)
+{
+ struct anon_vma *anon_vma = vma->anon_vma;
+
+ VM_BUG_ON(!PageLocked(page));
+ VM_BUG_ON(!anon_vma);
+ VM_BUG_ON(page->index != linear_page_index(vma, address));
+
+ anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON;
+ page->mapping = (struct address_space *) anon_vma;
+}
+
+/**
* __page_set_anon_rmap - setup new anonymous rmap
* @page: the page to add the mapping to
* @vma: the vm area in which the mapping is added

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