diff --git a/[refs] b/[refs]
index 6f8f47d2a5e6..e7cac8fdd992 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 2eccd6f65a0d4844318b1e30755cafd063833908
+refs/heads/master: 4ba51fd75cc3789be83f0d6f878dabbb0cb19bca
diff --git a/trunk/arch/x86/kernel/step.c b/trunk/arch/x86/kernel/step.c
index 9d406cdc847f..071ff4798236 100644
--- a/trunk/arch/x86/kernel/step.c
+++ b/trunk/arch/x86/kernel/step.c
@@ -140,6 +140,9 @@ static int enable_single_step(struct task_struct *child)
  */
 static void write_debugctlmsr(struct task_struct *child, unsigned long val)
 {
+	if (child->thread.debugctlmsr == val)
+		return;
+
 	child->thread.debugctlmsr = val;
 
 	if (child != current)
@@ -165,11 +168,11 @@ static void enable_step(struct task_struct *child, bool block)
 		write_debugctlmsr(child,
 				  child->thread.debugctlmsr | DEBUGCTLMSR_BTF);
 	} else {
-	    write_debugctlmsr(child,
-			      child->thread.debugctlmsr & ~DEBUGCTLMSR_BTF);
+		write_debugctlmsr(child,
+				  child->thread.debugctlmsr & ~DEBUGCTLMSR_BTF);
 
-	    if (!child->thread.debugctlmsr)
-		    clear_tsk_thread_flag(child, TIF_DEBUGCTLMSR);
+		if (!child->thread.debugctlmsr)
+			clear_tsk_thread_flag(child, TIF_DEBUGCTLMSR);
 	}
 }