---

yaml --- r: 186211 b: refs/heads/master c: c44b674 h: refs/heads/master i: 186209: e07f902 186207: efec01c v: v3
git-mirror · Mar 6, 2010 · f2d58a1 · f2d58a1
1 parent 1e39aac
commit f2d58a1
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Showing 4 changed files with 33 additions and 1 deletion.
diff --git a/[refs] b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 033a64b56aed798991de18d226085dfb1ccd858d
+refs/heads/master: c44b674323f4a2480dbeb65d4b487fa5f06f49e0
diff --git a/trunk/include/linux/rmap.h b/trunk/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/trunk/mm/memory.c b/trunk/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/trunk/mm/rmap.c b/trunk/mm/rmap.c
@@ -715,6 +715,30 @@ 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