frv: Prepare distangling page-fault logic from preempt_count

With the separation of pagefault_{disable,enable}() from the
preempt_count a previously overlooked dependancy became painfully
clear.

kmap_atomic() is per cpu and relies not only on disabling the
pagefault handler, but really needs preemption disabled too.

Make this explicit now - so that we can change pagefault_disable().
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

arch/frv/include/asm/highmem.h

@@ -116,6 +116,7 @@ static inline void *kmap_atomic(struct page *page, enum km_type type)
 {
 	unsigned long paddr;
 
+	preempt_disable();
 	pagefault_disable();
 	debug_kmap_atomic(type);
 	paddr = page_to_phys(page);
@@ -173,6 +174,7 @@ static inline void kunmap_atomic(void *kvaddr, enum km_type type)
 		BUG();
 	}
 	pagefault_enable();
+	preempt_enable();
 }
 
 #endif /* !__ASSEMBLY__ */