1 files changed, 29 insertions, 13 deletions

diff --git a/mm/rmap.c b/mm/rmap.c
index eaa7a09..0feeef8 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -133,8 +133,8 @@ int anon_vma_prepare(struct vm_area_struct *vma)
 				goto out_enomem_free_avc;
 			allocated = anon_vma;
 		}
-		spin_lock(&anon_vma->lock);
 
+		spin_lock(&anon_vma->lock);
 		/* page_table_lock to protect against threads */
 		spin_lock(&mm->page_table_lock);
 		if (likely(!vma->anon_vma)) {
@@ -144,14 +144,15 @@ int anon_vma_prepare(struct vm_area_struct *vma)
 			list_add(&avc->same_vma, &vma->anon_vma_chain);
 			list_add(&avc->same_anon_vma, &anon_vma->head);
 			allocated = NULL;
+			avc = NULL;
 		}
 		spin_unlock(&mm->page_table_lock);
-
 		spin_unlock(&anon_vma->lock);
-		if (unlikely(allocated)) {
+
+		if (unlikely(allocated))
 			anon_vma_free(allocated);
+		if (unlikely(avc))
 			anon_vma_chain_free(avc);
-		}
 	}
 	return 0;
 
@@ -182,7 +183,7 @@ int anon_vma_clone(struct vm_area_struct *dst, struct vm_area_struct *src)
 {
 	struct anon_vma_chain *avc, *pavc;
 
-	list_for_each_entry(pavc, &src->anon_vma_chain, same_vma) {
+	list_for_each_entry_reverse(pavc, &src->anon_vma_chain, same_vma) {
 		avc = anon_vma_chain_alloc();
 		if (!avc)
 			goto enomem_failure;
@@ -335,14 +336,13 @@ vma_address(struct page *page, struct vm_area_struct *vma)
 
 /*
  * At what user virtual address is page expected in vma?
- * checking that the page matches the vma.
+ * Caller should check the page is actually part of the vma.
  */
 unsigned long page_address_in_vma(struct page *page, struct vm_area_struct *vma)
 {
-	if (PageAnon(page)) {
-		if (vma->anon_vma != page_anon_vma(page))
-			return -EFAULT;
-	} else if (page->mapping && !(vma->vm_flags & VM_NONLINEAR)) {
+	if (PageAnon(page))
+		;
+	else if (page->mapping && !(vma->vm_flags & VM_NONLINEAR)) {
 		if (!vma->vm_file ||
 		    vma->vm_file->f_mapping != page->mapping)
 			return -EFAULT;
@@ -730,13 +730,29 @@ void page_move_anon_rmap(struct page *page,
  * @page:	the page to add the mapping to
  * @vma:	the vm area in which the mapping is added
  * @address:	the user virtual address mapped
+ * @exclusive:	the page is exclusively owned by the current process
  */
 static void __page_set_anon_rmap(struct page *page,
-	struct vm_area_struct *vma, unsigned long address)
+	struct vm_area_struct *vma, unsigned long address, int exclusive)
 {
 	struct anon_vma *anon_vma = vma->anon_vma;
 
 	BUG_ON(!anon_vma);
+
+	/*
+	 * If the page isn't exclusively mapped into this vma,
+	 * we must use the _oldest_ possible anon_vma for the
+	 * page mapping!
+	 *
+	 * So take the last AVC chain entry in the vma, which is
+	 * the deepest ancestor, and use the anon_vma from that.
+	 */
+	if (!exclusive) {
+		struct anon_vma_chain *avc;
+		avc = list_entry(vma->anon_vma_chain.prev, struct anon_vma_chain, same_vma);
+		anon_vma = avc->anon_vma;
+	}
+
 	anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON;
 	page->mapping = (struct address_space *) anon_vma;
 	page->index = linear_page_index(vma, address);
@@ -791,7 +807,7 @@ void page_add_anon_rmap(struct page *page,
 	VM_BUG_ON(!PageLocked(page));
 	VM_BUG_ON(address < vma->vm_start || address >= vma->vm_end);
 	if (first)
-		__page_set_anon_rmap(page, vma, address);
+		__page_set_anon_rmap(page, vma, address, 0);
 	else
 		__page_check_anon_rmap(page, vma, address);
 }
@@ -813,7 +829,7 @@ void page_add_new_anon_rmap(struct page *page,
 	SetPageSwapBacked(page);
 	atomic_set(&page->_mapcount, 0); /* increment count (starts at -1) */
 	__inc_zone_page_state(page, NR_ANON_PAGES);
-	__page_set_anon_rmap(page, vma, address);
+	__page_set_anon_rmap(page, vma, address, 1);
 	if (page_evictable(page, vma))
 		lru_cache_add_lru(page, LRU_ACTIVE_ANON);
 	else