1 files changed, 10 insertions, 1 deletions

diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 8137482abd6e..c689b60af000 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -69,6 +69,12 @@ static inline long sync_writeback_pages(void)
 int dirty_background_ratio = 5;
 
 /*
+ * free highmem will not be subtracted from the total free memory
+ * for calculating free ratios if vm_highmem_is_dirtyable is true
+ */
+int vm_highmem_is_dirtyable;
+
+/*
  * The generator of dirty data starts writeback at this percentage
  */
 int vm_dirty_ratio = 10;
@@ -287,7 +293,10 @@ static unsigned long determine_dirtyable_memory(void)
         x = global_page_state(NR_FREE_PAGES)
                 + global_page_state(NR_INACTIVE)
                 + global_page_state(NR_ACTIVE);
-        x -= highmem_dirtyable_memory(x);
+
+        if (!vm_highmem_is_dirtyable)
+                x -= highmem_dirtyable_memory(x);
+
         return x + 1;   /* Ensure that we never return 0 */
 }