4.9-stable review patch. If anyone has any objections, please let me know. ------------------ From: Randy Dunlap <rdunlap@xxxxxxxxxxxxx> [ Upstream commit 3705ccfdd1e8b539225ce20e3925a945cc788d67 ] When CONFIG_FPU is not enabled on arch/mn10300, <asm/switch_to.h> causes a build error with a call to fpu_save(): kernel/built-in.o: In function `.L410': core.c:(.sched.text+0x28a): undefined reference to `fpu_save' Fix this by including <asm/fpu.h> in <asm/switch_to.h> so that an empty static inline fpu_save() is defined. Link: http://lkml.kernel.org/r/dc421c4f-4842-4429-1b99-92865c2f24b6@xxxxxxxxxxxxx Signed-off-by: Randy Dunlap <rdunlap@xxxxxxxxxxxxx> Reported-by: kbuild test robot <fengguang.wu@xxxxxxxxx> Reviewed-by: David Howells <dhowells@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- arch/mn10300/include/asm/switch_to.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/arch/mn10300/include/asm/switch_to.h +++ b/arch/mn10300/include/asm/switch_to.h @@ -16,7 +16,7 @@ struct task_struct; struct thread_struct; -#if !defined(CONFIG_LAZY_SAVE_FPU) +#if defined(CONFIG_FPU) && !defined(CONFIG_LAZY_SAVE_FPU) struct fpu_state_struct; extern asmlinkage void fpu_save(struct fpu_state_struct *); #define switch_fpu(prev, next) \