1 files changed, 4 insertions, 1 deletions

diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 28763b8bdbdd..2cb01f6ec5d0 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -410,9 +410,12 @@ void global_dirty_limits(unsigned long *pbackground, unsigned long *pdirty)
 {
         unsigned long background;
         unsigned long dirty;
-        unsigned long available_memory = determine_dirtyable_memory();
+        unsigned long uninitialized_var(available_memory);
         struct task_struct *tsk;
 
+        if (!vm_dirty_bytes || !dirty_background_bytes)
+                available_memory = determine_dirtyable_memory();
+
         if (vm_dirty_bytes)
                 dirty = DIV_ROUND_UP(vm_dirty_bytes, PAGE_SIZE);
         else