From 2afb01726c50c8d7364565b4d80bd98cdc94d46e Mon Sep 17 00:00:00 2001
From: Heiko Carstens <heiko.carstens@de.ibm.com>
Date: Mon, 25 Oct 2010 16:10:18 +0200
Subject: [PATCH] --- yaml --- r: 216749 b: refs/heads/master c:
 fdb6d070effba1871f0bb980cf3c3b8738803414 h: refs/heads/master i:   216747:
 442ebb51cb11c6e9322dd8adaab9ff257a650557 v: v3

---
 [refs]                               |  2 +-
 trunk/arch/s390/include/asm/system.h | 20 ++++++++++++--------
 2 files changed, 13 insertions(+), 9 deletions(-)

diff --git a/[refs] b/[refs]
index 3a2ff3e6270c..a95bc9ff789e 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: f861e4057263033ad9134bfd6745f91b2165b351
+refs/heads/master: fdb6d070effba1871f0bb980cf3c3b8738803414
diff --git a/trunk/arch/s390/include/asm/system.h b/trunk/arch/s390/include/asm/system.h
index 1f2ebc4afd82..c35d0a383f00 100644
--- a/trunk/arch/s390/include/asm/system.h
+++ b/trunk/arch/s390/include/asm/system.h
@@ -85,14 +85,18 @@ static inline void restore_access_regs(unsigned int *acrs)
 	asm volatile("lam 0,15,%0" : : "Q" (*acrs));
 }
 
-#define switch_to(prev,next,last) do {					     \
-	if (prev == next)						     \
-		break;							     \
-	save_fp_regs(&prev->thread.fp_regs);				     \
-	restore_fp_regs(&next->thread.fp_regs);				     \
-	save_access_regs(&prev->thread.acrs[0]);			     \
-	restore_access_regs(&next->thread.acrs[0]);			     \
-	prev = __switch_to(prev,next);					     \
+#define switch_to(prev,next,last) do {					\
+	if (prev == next)						\
+		break;							\
+	if (prev->mm) {							\
+		save_fp_regs(&prev->thread.fp_regs);			\
+		save_access_regs(&prev->thread.acrs[0]);		\
+	}								\
+	if (next->mm) {							\
+		restore_fp_regs(&next->thread.fp_regs);			\
+		restore_access_regs(&next->thread.acrs[0]);		\
+	}								\
+	prev = __switch_to(prev,next);					\
 } while (0)
 
 extern void account_vtime(struct task_struct *, struct task_struct *);