rmap: remove anon_vma check in page_address_in_vma()

[pandora-kernel.git] / mm / rmap.c

diff --git a/mm/rmap.c b/mm/rmap.c
index 4bad326..0feeef8 100644 (file)
--- 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;
 
@@ -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;
@@ -730,23 +730,28 @@ 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_chain *avc;
-       struct anon_vma *anon_vma;
+       struct anon_vma *anon_vma = vma->anon_vma;
 
-       BUG_ON(!vma->anon_vma);
+       BUG_ON(!anon_vma);
 
        /*
-        * We must use the _oldest_ possible anon_vma for the page mapping!
+        * 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.
+        * So take the last AVC chain entry in the vma, which is
+        * the deepest ancestor, and use the anon_vma from that.
         */
-       avc = list_entry(vma->anon_vma_chain.prev, struct anon_vma_chain, same_vma);
-       anon_vma = avc->anon_vma;
+       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;
@@ -802,7 +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);
 }
@@ -824,7 +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