mm: make free_reserved_area() return "const char *"

and propagate through down the call stack.

Link: http://lkml.kernel.org/r/20181124091411.GC10969@avx2
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index 071b2a6..3305143 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -967,7 +967,7 @@ static inline uint32_t hypervisor_cpuid_base(const char *sig, uint32_t leaves)
 }
 
 extern unsigned long arch_align_stack(unsigned long sp);
-extern void free_init_pages(char *what, unsigned long begin, unsigned long end);
+void free_init_pages(const char *what, unsigned long begin, unsigned long end);
 extern void free_kernel_image_pages(void *begin, void *end);
 
 void default_idle(void);
diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c
index 427a955..f905a23 100644
--- a/arch/x86/mm/init.c
+++ b/arch/x86/mm/init.c
@@ -742,7 +742,7 @@ int devmem_is_allowed(unsigned long pagenr)
 	return 1;
 }
 
-void free_init_pages(char *what, unsigned long begin, unsigned long end)
+void free_init_pages(const char *what, unsigned long begin, unsigned long end)
 {
 	unsigned long begin_aligned, end_aligned;