1 files changed, 19 insertions, 11 deletions

diff --git a/mm/swap_state.c b/mm/swap_state.c
index d8aadaf2a0ba..b8035b055129 100644
--- a/mm/swap_state.c
+++ b/mm/swap_state.c
@@ -39,7 +39,7 @@ static struct backing_dev_info swap_backing_dev_info = {
 
 struct address_space swapper_space = {
         .page_tree      = RADIX_TREE_INIT(GFP_ATOMIC|__GFP_NOWARN),
-        .tree_lock      = __RW_LOCK_UNLOCKED(swapper_space.tree_lock),
+        .tree_lock      = __SPIN_LOCK_UNLOCKED(swapper_space.tree_lock),
         .a_ops          = &swap_aops,
         .i_mmap_nonlinear = LIST_HEAD_INIT(swapper_space.i_mmap_nonlinear),
         .backing_dev_info = &swap_backing_dev_info,
@@ -56,7 +56,8 @@ static struct {
 
 void show_swap_cache_info(void)
 {
-        printk("Swap cache: add %lu, delete %lu, find %lu/%lu\n",
+        printk("%lu pages in swap cache\n", total_swapcache_pages);
+        printk("Swap cache stats: add %lu, delete %lu, find %lu/%lu\n",
                 swap_cache_info.add_total, swap_cache_info.del_total,
                 swap_cache_info.find_success, swap_cache_info.find_total);
         printk("Free swap  = %lukB\n", nr_swap_pages << (PAGE_SHIFT - 10));
@@ -64,7 +65,7 @@ void show_swap_cache_info(void)
 }
 
 /*
- * add_to_swap_cache resembles add_to_page_cache on swapper_space,
+ * add_to_swap_cache resembles add_to_page_cache_locked on swapper_space,
  * but sets SwapCache flag and private instead of mapping and index.
  */
 int add_to_swap_cache(struct page *page, swp_entry_t entry, gfp_t gfp_mask)
@@ -76,19 +77,26 @@ int add_to_swap_cache(struct page *page, swp_entry_t entry, gfp_t gfp_mask)
         BUG_ON(PagePrivate(page));
         error = radix_tree_preload(gfp_mask);
         if (!error) {
-                write_lock_irq(&swapper_space.tree_lock);
+                page_cache_get(page);
+                SetPageSwapCache(page);
+                set_page_private(page, entry.val);
+
+                spin_lock_irq(&swapper_space.tree_lock);
                 error = radix_tree_insert(&swapper_space.page_tree,
                                                 entry.val, page);
-                if (!error) {
-                        page_cache_get(page);
-                        SetPageSwapCache(page);
-                        set_page_private(page, entry.val);
+                if (likely(!error)) {
                         total_swapcache_pages++;
                         __inc_zone_page_state(page, NR_FILE_PAGES);
                         INC_CACHE_INFO(add_total);
                 }
-                write_unlock_irq(&swapper_space.tree_lock);
+                spin_unlock_irq(&swapper_space.tree_lock);
                 radix_tree_preload_end();
+
+                if (unlikely(error)) {
+                        set_page_private(page, 0UL);
+                        ClearPageSwapCache(page);
+                        page_cache_release(page);
+                }
         }
         return error;
 }
@@ -175,9 +183,9 @@ void delete_from_swap_cache(struct page *page)
 
         entry.val = page_private(page);
 
-        write_lock_irq(&swapper_space.tree_lock);
+        spin_lock_irq(&swapper_space.tree_lock);
         __delete_from_swap_cache(page);
-        write_unlock_irq(&swapper_space.tree_lock);
+        spin_unlock_irq(&swapper_space.tree_lock);
 
         swap_free(entry);
         page_cache_release(page);