[Patch v3 5/5] mm/page_alloc.c: extract check_[new|free]_page_bad() common part to page_bad_reason()

[Wei Yang <richard.weiyang@xxxxxxxxx>]

We share the similar code in check_[new|free]_page_bad() to get the
page's bad reason.

Let's extract it and reduce code duplication.

Signed-off-by: Wei Yang <richard.weiyang@xxxxxxxxx>
---
 mm/page_alloc.c | 36 +++++++++++++++++-------------------
 1 file changed, 17 insertions(+), 19 deletions(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index dfcf2682ed40..c12a5a9b79c8 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1013,7 +1013,7 @@ static inline bool page_expected_state(struct page *page,
 	return true;
 }
 
-static void check_free_page_bad(struct page *page)
+static const char *page_bad_reason(struct page *page, unsigned long flags)
 {
 	const char *bad_reason = NULL;
 
@@ -1023,13 +1023,23 @@ static void check_free_page_bad(struct page *page)
 		bad_reason = "non-NULL mapping";
 	if (unlikely(page_ref_count(page) != 0))
 		bad_reason = "nonzero _refcount";
-	if (unlikely(page->flags & PAGE_FLAGS_CHECK_AT_FREE))
-		bad_reason = "PAGE_FLAGS_CHECK_AT_FREE flag(s) set";
+	if (unlikely(page->flags & flags)) {
+		if (flags == PAGE_FLAGS_CHECK_AT_PREP)
+			bad_reason = "PAGE_FLAGS_CHECK_AT_PREP flag(s) set";
+		else
+			bad_reason = "PAGE_FLAGS_CHECK_AT_FREE flag(s) set";
+	}
 #ifdef CONFIG_MEMCG
 	if (unlikely(page->mem_cgroup))
 		bad_reason = "page still charged to cgroup";
 #endif
-	bad_page(page, bad_reason);
+	return bad_reason;
+}
+
+static void check_free_page_bad(struct page *page)
+{
+	bad_page(page,
+		 page_bad_reason(page, PAGE_FLAGS_CHECK_AT_FREE));
 }
 
 static inline int check_free_page(struct page *page)
@@ -2023,26 +2033,14 @@ static inline void expand(struct zone *zone, struct page *page,
 
 static void check_new_page_bad(struct page *page)
 {
-	const char *bad_reason = NULL;
-
 	if (unlikely(page->flags & __PG_HWPOISON)) {
 		/* Don't complain about hwpoisoned pages */
 		page_mapcount_reset(page); /* remove PageBuddy */
 		return;
 	}
-	if (unlikely(atomic_read(&page->_mapcount) != -1))
-		bad_reason = "nonzero mapcount";
-	if (unlikely(page->mapping != NULL))
-		bad_reason = "non-NULL mapping";
-	if (unlikely(page_ref_count(page) != 0))
-		bad_reason = "nonzero _refcount";
-	if (unlikely(page->flags & PAGE_FLAGS_CHECK_AT_PREP))
-		bad_reason = "PAGE_FLAGS_CHECK_AT_PREP flag set";
-#ifdef CONFIG_MEMCG
-	if (unlikely(page->mem_cgroup))
-		bad_reason = "page still charged to cgroup";
-#endif
-	bad_page(page, bad_reason);
+
+	bad_page(page,
+		 page_bad_reason(page, PAGE_FLAGS_CHECK_AT_PREP));
 }
 
 /*
-- 
2.23.0