1 files changed, 23 insertions, 4 deletions

diff --git a/mm/swapfile.c b/mm/swapfile.c
index 1e330f2998fa..90cb67a5417c 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -344,7 +344,7 @@ int can_share_swap_page(struct page *page)
  * Work out if there are any other processes sharing this
  * swap cache page. Free it if you can. Return success.
  */
-int remove_exclusive_swap_page(struct page *page)
+static int remove_exclusive_swap_page_count(struct page *page, int count)
 {
         int retval;
         struct swap_info_struct * p;
@@ -357,7 +357,7 @@ int remove_exclusive_swap_page(struct page *page)
                 return 0;
         if (PageWriteback(page))
                 return 0;
-        if (page_count(page) != 2) /* 2: us + cache */
+        if (page_count(page) != count) /* us + cache + ptes */
                 return 0;
 
         entry.val = page_private(page);
@@ -370,7 +370,7 @@ int remove_exclusive_swap_page(struct page *page)
         if (p->swap_map[swp_offset(entry)] == 1) {
                 /* Recheck the page count with the swapcache lock held.. */
                 spin_lock_irq(&swapper_space.tree_lock);
-                if ((page_count(page) == 2) && !PageWriteback(page)) {
+                if ((page_count(page) == count) && !PageWriteback(page)) {
                         __delete_from_swap_cache(page);
                         SetPageDirty(page);
                         retval = 1;
@@ -388,6 +388,25 @@ int remove_exclusive_swap_page(struct page *page)
 }
 
 /*
+ * Most of the time the page should have two references: one for the
+ * process and one for the swap cache.
+ */
+int remove_exclusive_swap_page(struct page *page)
+{
+        return remove_exclusive_swap_page_count(page, 2);
+}
+
+/*
+ * The pageout code holds an extra reference to the page.  That raises
+ * the reference count to test for to 2 for a page that is only in the
+ * swap cache plus 1 for each process that maps the page.
+ */
+int remove_exclusive_swap_page_ref(struct page *page)
+{
+        return remove_exclusive_swap_page_count(page, 2 + page_mapcount(page));
+}
+
+/*
  * Free the swap entry like above, but also try to
  * free the page cache entry if it is the last user.
  */
@@ -403,7 +422,7 @@ void free_swap_and_cache(swp_entry_t entry)
         if (p) {
                 if (swap_entry_free(p, swp_offset(entry)) == 1) {
                         page = find_get_page(&swapper_space, entry.val);
-                        if (page && unlikely(!trylock_page(page))) {
+                        if (page && !trylock_page(page)) {
                                 page_cache_release(page);
                                 page = NULL;
                         }