VServer 1.9.2 (patch-2.6.8.1-vs1.9.2.diff)

[linux-2.6.git] / mm / rmap.c

diff --git a/mm/rmap.c b/mm/rmap.c
index 2dae0a8..c8e236e 100644 (file)
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -18,14 +18,11 @@
  */
 
 /*
- * Locking:
- * - the page->mapcount field is protected by the PG_maplock bit,
- *   which nests within the mm->page_table_lock,
- *   which nests within the page lock.
- * - because swapout locking is opposite to the locking order
- *   in the page fault path, the swapout path uses trylocks
- *   on the mm->page_table_lock
+ * Locking: see "Lock ordering" summary in filemap.c.
+ * In swapout, page_map_lock is held on entry to page_referenced and
+ * try_to_unmap, so they trylock for i_mmap_lock and page_table_lock.
  */
+
 #include <linux/mm.h>
 #include <linux/pagemap.h>
 #include <linux/swap.h>
@@ -80,8 +77,12 @@ int anon_vma_prepare(struct vm_area_struct *vma)
                /* page_table_lock to protect against threads */
                spin_lock(&mm->page_table_lock);
                if (likely(!vma->anon_vma)) {
+                       if (!allocated)
+                               spin_lock(&anon_vma->lock);
                        vma->anon_vma = anon_vma;
                        list_add(&vma->anon_vma_node, &anon_vma->head);
+                       if (!allocated)
+                               spin_unlock(&anon_vma->lock);
                        allocated = NULL;
                }
                spin_unlock(&mm->page_table_lock);
@@ -227,7 +228,7 @@ static int page_referenced_one(struct page *page,
        if (page_to_pfn(page) != pte_pfn(*pte))
                goto out_unmap;
 
-       if (ptep_test_and_clear_young(pte))
+       if (ptep_clear_flush_young(vma, address, pte))
                referenced++;
 
        (*mapcount)--;
@@ -466,7 +467,7 @@ static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma)
         * skipped over this mm) then we should reactivate it.
         */
        if ((vma->vm_flags & (VM_LOCKED|VM_RESERVED)) ||
-                       ptep_test_and_clear_young(pte)) {
+                       ptep_clear_flush_young(vma, address, pte)) {
                ret = SWAP_FAIL;
                goto out_unmap;
        }
@@ -481,6 +482,10 @@ static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma)
         * an exclusive swap page, do_wp_page will replace it by a copy
         * page, and the user never get to see the data GUP was holding
         * the original page for.
+        *
+        * This test is also useful for when swapoff (unuse_process) has
+        * to drop page lock: its reference to the page stops existing
+        * ptes from being unmapped, so swapoff can make progress.
         */
        if (PageSwapCache(page) &&
            page_count(page) != page->mapcount + 2) {
@@ -594,7 +599,7 @@ static int try_to_unmap_cluster(unsigned long cursor,
                if (PageReserved(page))
                        continue;
 
-               if (ptep_test_and_clear_young(pte))
+               if (ptep_clear_flush_young(vma, address, pte))
                        continue;
 
                /* Nuke the page table entry. */
@@ -742,7 +747,7 @@ static inline int try_to_unmap_file(struct page *page)
        list_for_each_entry(vma, &mapping->i_mmap_nonlinear,
                                                shared.vm_set.list) {
                if (!(vma->vm_flags & VM_RESERVED))
-                       vma->vm_private_data = 0;
+                       vma->vm_private_data = NULL;
        }
 relock:
        page_map_lock(page);