---

 b/mm/memory.c |    3 +++
 1 file changed, 3 insertions(+)

diff -puN mm/memory.c~fix-old-need_flush-logic mm/memory.c
--- a/mm/memory.c~fix-old-need_flush-logic	2014-12-16 13:24:27.338557014 -0800
+++ b/mm/memory.c	2014-12-16 13:24:50.412598019 -0800
@@ -258,6 +258,9 @@ static void tlb_flush_mmu_free(struct mm
 
 void tlb_flush_mmu(struct mmu_gather *tlb)
 {
+	if (!tlb->end)
+		return;
+
 	tlb_flush_mmu_tlbonly(tlb);
 	tlb_flush_mmu_free(tlb);
 }
_