Build error for nommu if CONFIG_DEBUG_ATOMIC_SLEEP is selected

[Axel Lin]

Hi Michael,

I got below build error for nommu if CONFIG_DEBUG_ATOMIC_SLEEP is selected.
Also got the same build error if CONFIG_PROVE_LOCKING is selected.

Seems this issue is introduced by commit 662bbcb2747c2
"mm, sched: Allow uaccess in atomic with pagefault_disable()".

arch/arm/kernel/built-in.o: In function `arch_ptrace':
arch/arm/kernel/ptrace.c:852: undefined reference to `might_fault'
arch/arm/kernel/built-in.o: In function `restore_sigframe':
arch/arm/kernel/signal.c:173: undefined reference to `might_fault'
arch/arm/kernel/signal.c:174: undefined reference to `might_fault'
arch/arm/kernel/signal.c:175: undefined reference to `might_fault'
arch/arm/kernel/signal.c:176: undefined reference to `might_fault'
arch/arm/kernel/built-in.o:arch/arm/kernel/signal.c:177: more undefined references to `might_fault' follow
make: *** [vmlinux] Error 1

Regards,
Axel