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>

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);

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;
 

include/linux/mm.h

@@ -2108,7 +2108,7 @@ extern void free_initmem(void);
  * Return pages freed into the buddy system.
  */
 extern unsigned long free_reserved_area(void *start, void *end,
-					int poison, char *s);
+					int poison, const char *s);
 
 #ifdef	CONFIG_HIGHMEM
 /*

mm/page_alloc.c

@@ -7193,7 +7193,7 @@ void adjust_managed_page_count(struct page *page, long count)
 }
 EXPORT_SYMBOL(adjust_managed_page_count);
 
-unsigned long free_reserved_area(void *start, void *end, int poison, char *s)
+unsigned long free_reserved_area(void *start, void *end, int poison, const char *s)
 {
 	void *pos;
 	unsigned long pages = 0;