[PATCH] mm: use 'const char *' insted of 'char *' for reason in dump_page()

["Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx>]

I tried to use 'dump_page(page, __func__)' for debugging, but it
triggers warning:

  warning: passing argument 2 of ‘dump_page’ discards ‘const’ qualifier from pointer target type [enabled by default]

Let's convert 'reason' to 'const char *' in dump_page() and friends:
we shouldn't modify it anyway.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
---
 include/linux/mmdebug.h |  4 ++--
 mm/page_alloc.c         | 12 +++++++-----
 2 files changed, 9 insertions(+), 7 deletions(-)

diff --git a/include/linux/mmdebug.h b/include/linux/mmdebug.h
index 5042c036dda9..2d57efa64cc1 100644
--- a/include/linux/mmdebug.h
+++ b/include/linux/mmdebug.h
@@ -3,8 +3,8 @@
 
 struct page;
 
-extern void dump_page(struct page *page, char *reason);
-extern void dump_page_badflags(struct page *page, char *reason,
+extern void dump_page(struct page *page, const char *reason);
+extern void dump_page_badflags(struct page *page, const char *reason,
 			       unsigned long badflags);
 
 #ifdef CONFIG_DEBUG_VM
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index e3758a09a009..a648a11f1108 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -295,7 +295,8 @@ static inline int bad_range(struct zone *zone, struct page *page)
 }
 #endif
 
-static void bad_page(struct page *page, char *reason, unsigned long bad_flags)
+static void bad_page(struct page *page, const char *reason,
+		unsigned long bad_flags)
 {
 	static unsigned long resume;
 	static unsigned long nr_shown;
@@ -621,7 +622,7 @@ out:
 
 static inline int free_pages_check(struct page *page)
 {
-	char *bad_reason = NULL;
+	const char *bad_reason = NULL;
 	unsigned long bad_flags = 0;
 
 	if (unlikely(page_mapcount(page)))
@@ -857,7 +858,7 @@ static inline void expand(struct zone *zone, struct page *page,
  */
 static inline int check_new_page(struct page *page)
 {
-	char *bad_reason = NULL;
+	const char *bad_reason = NULL;
 	unsigned long bad_flags = 0;
 
 	if (unlikely(page_mapcount(page)))
@@ -6524,7 +6525,8 @@ static void dump_page_flags(unsigned long flags)
 	printk(")\n");
 }
 
-void dump_page_badflags(struct page *page, char *reason, unsigned long badflags)
+void dump_page_badflags(struct page *page, const char *reason,
+		unsigned long badflags)
 {
 	printk(KERN_ALERT
 	       "page:%p count:%d mapcount:%d mapping:%p index:%#lx\n",
@@ -6540,7 +6542,7 @@ void dump_page_badflags(struct page *page, char *reason, unsigned long badflags)
 	mem_cgroup_print_bad_page(page);
 }
 
-void dump_page(struct page *page, char *reason)
+void dump_page(struct page *page, const char *reason)
 {
 	dump_page_badflags(page, reason, 0);
 }
-- 
1.9.0

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