diff --git a/arch/x86_64/ia32/ptrace32.c b/arch/x86_64/ia32/ptrace32.c
index 72bf92a9d375..d18198ed636b 100644
--- a/arch/x86_64/ia32/ptrace32.c
+++ b/arch/x86_64/ia32/ptrace32.c
@@ -375,8 +375,10 @@ asmlinkage long sys32_ptrace(long request, u32 pid, u32 addr, u32 data)
 		ret = -EIO;
 		if (!access_ok(VERIFY_READ, u, sizeof(*u)))
 			break;
-		/* no checking to be bug-to-bug compatible with i386 */
-		__copy_from_user(&child->thread.i387.fxsave, u, sizeof(*u));
+		/* no checking to be bug-to-bug compatible with i386. */
+		/* but silence warning */
+		if (__copy_from_user(&child->thread.i387.fxsave, u, sizeof(*u)))
+			;
 		set_stopped_child_used_math(child);
 		child->thread.i387.fxsave.mxcsr &= mxcsr_feature_mask;
 		ret = 0; 
diff --git a/include/asm-x86_64/i387.h b/include/asm-x86_64/i387.h
index 60c0f4853fdb..0217b74cc9fc 100644
--- a/include/asm-x86_64/i387.h
+++ b/include/asm-x86_64/i387.h
@@ -137,8 +137,8 @@ static inline int save_i387_checking(struct i387_fxsave_struct __user *fx)
 #else
 		     : [fx] "cdaSDb" (fx), "0" (0));
 #endif
-	if (unlikely(err))
-		__clear_user(fx, sizeof(struct i387_fxsave_struct));
+	if (unlikely(err) && __clear_user(fx, sizeof(struct i387_fxsave_struct)))
+		err = -EFAULT;
 	/* No need to clear here because the caller clears USED_MATH */
 	return err;
 } 
diff --git a/include/asm-x86_64/uaccess.h b/include/asm-x86_64/uaccess.h
index bc6812009bd7..802a4a068ef6 100644
--- a/include/asm-x86_64/uaccess.h
+++ b/include/asm-x86_64/uaccess.h
@@ -237,14 +237,18 @@ do {									\
  */
 
 /* Handles exceptions in both to and from, but doesn't do access_ok */
-extern unsigned long copy_user_generic(void *to, const void *from, unsigned len); 
-extern unsigned long copy_user_generic_dontzero(void *to, const void *from, unsigned len);
+__must_check unsigned long
+copy_user_generic(void *to, const void *from, unsigned len);
 
-extern unsigned long copy_to_user(void __user *to, const void *from, unsigned len); 
-extern unsigned long copy_from_user(void *to, const void __user *from, unsigned len); 
-extern unsigned long copy_in_user(void __user *to, const void __user *from, unsigned len); 
+__must_check unsigned long
+copy_to_user(void __user *to, const void *from, unsigned len);
+__must_check unsigned long
+copy_from_user(void *to, const void __user *from, unsigned len);
+__must_check unsigned long
+copy_in_user(void __user *to, const void __user *from, unsigned len);
 
-static __always_inline int __copy_from_user(void *dst, const void __user *src, unsigned size)
+static __always_inline __must_check
+int __copy_from_user(void *dst, const void __user *src, unsigned size)
 { 
        int ret = 0;
 	if (!__builtin_constant_p(size))
@@ -273,7 +277,8 @@ static __always_inline int __copy_from_user(void *dst, const void __user *src, u
 	}
 }	
 
-static __always_inline int __copy_to_user(void __user *dst, const void *src, unsigned size)
+static __always_inline __must_check
+int __copy_to_user(void __user *dst, const void *src, unsigned size)
 { 
        int ret = 0;
 	if (!__builtin_constant_p(size))
@@ -304,7 +309,8 @@ static __always_inline int __copy_to_user(void __user *dst, const void *src, uns
 	}
 }	
 
-static __always_inline int __copy_in_user(void __user *dst, const void __user *src, unsigned size)
+static __always_inline __must_check
+int __copy_in_user(void __user *dst, const void __user *src, unsigned size)
 { 
        int ret = 0;
 	if (!__builtin_constant_p(size))
@@ -344,15 +350,17 @@ static __always_inline int __copy_in_user(void __user *dst, const void __user *s
 	}
 }	
 
-long strncpy_from_user(char *dst, const char __user *src, long count);
-long __strncpy_from_user(char *dst, const char __user *src, long count);
-long strnlen_user(const char __user *str, long n);
-long __strnlen_user(const char __user *str, long n);
-long strlen_user(const char __user *str);
-unsigned long clear_user(void __user *mem, unsigned long len);
-unsigned long __clear_user(void __user *mem, unsigned long len);
+__must_check long 
+strncpy_from_user(char *dst, const char __user *src, long count);
+__must_check long 
+__strncpy_from_user(char *dst, const char __user *src, long count);
+__must_check long strnlen_user(const char __user *str, long n);
+__must_check long __strnlen_user(const char __user *str, long n);
+__must_check long strlen_user(const char __user *str);
+__must_check unsigned long clear_user(void __user *mem, unsigned long len);
+__must_check unsigned long __clear_user(void __user *mem, unsigned long len);
 
-extern long __copy_from_user_inatomic(void *dst, const void __user *src, unsigned size);
+__must_check long __copy_from_user_inatomic(void *dst, const void __user *src, unsigned size);
 #define __copy_to_user_inatomic copy_user_generic
 
 #endif /* __X86_64_UACCESS_H */