mm: speculative page references

[firefly-linux-kernel-4.4.55.git] / mm / swap_state.c

diff --git a/mm/swap_state.c b/mm/swap_state.c
index 50757ee3f9f3ee243ad23df60ae56a923bb0e64e..3e3381d6c7eee919e209834465add2277f987d22 100644 (file)
--- a/mm/swap_state.c
+++ b/mm/swap_state.c
@@ -33,7 +33,7 @@ static const struct address_space_operations swap_aops = {
 };
 
 static struct backing_dev_info swap_backing_dev_info = {
-       .capabilities   = BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_WRITEBACK,
+       .capabilities   = BDI_CAP_NO_ACCT_AND_WRITEBACK,
        .unplug_io_fn   = swap_unplug_io_fn,
 };
 
@@ -64,7 +64,7 @@ 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 +76,26 @@ 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) {
+               page_cache_get(page);
+               SetPageSwapCache(page);
+               set_page_private(page, entry.val);
+
                write_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);
                radix_tree_preload_end();
+
+               if (unlikely(error)) {
+                       set_page_private(page, 0UL);
+                       ClearPageSwapCache(page);
+                       page_cache_release(page);
+               }
        }
        return error;
 }