[PATCH] mm, page_alloc: uninline the bad page part of check_new_page()

[Vlastimil Babka]

Bad pages should be rare so the code handling them doesn't need to be inline
for performance reasons. Put it to separate function which returns void.
This also assumes that the initial page_expected_state() result will match the
result of the thorough check, i.e. the page doesn't become "good" in the
meanwhile. This matches the same expectations already in place in
free_pages_check().

!DEBUG_VM bloat-o-meter:

add/remove: 1/0 grow/shrink: 0/1 up/down: 134/-274 (-140)
function                                     old     new   delta
check_new_page_bad                             -     134    +134
get_page_from_freelist                      3468    3194    -274

Signed-off-by: Vlastimil Babka <vbabka@xxxxxxx>
---
 mm/page_alloc.c | 33 +++++++++++++++++----------------
 1 file changed, 17 insertions(+), 16 deletions(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 2b3aefdfcaa2..755ec9465d8a 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1648,19 +1648,11 @@ static inline void expand(struct zone *zone, struct page *page,
 	}
 }
 
-/*
- * This page is about to be returned from the page allocator
- */
-static inline int check_new_page(struct page *page)
+static void check_new_page_bad(struct page *page)
 {
-	const char *bad_reason;
-	unsigned long bad_flags;
+	const char *bad_reason = NULL;
+	unsigned long bad_flags = 0;
 
-	if (page_expected_state(page, PAGE_FLAGS_CHECK_AT_PREP|__PG_HWPOISON))
-		return 0;
-
-	bad_reason = NULL;
-	bad_flags = 0;
 	if (unlikely(atomic_read(&page->_mapcount) != -1))
 		bad_reason = "nonzero mapcount";
 	if (unlikely(page->mapping != NULL))
@@ -1679,11 +1671,20 @@ static inline int check_new_page(struct page *page)
 	if (unlikely(page->mem_cgroup))
 		bad_reason = "page still charged to cgroup";
 #endif
-	if (unlikely(bad_reason)) {
-		bad_page(page, bad_reason, bad_flags);
-		return 1;
-	}
-	return 0;
+	bad_page(page, bad_reason, bad_flags);
+}
+
+/*
+ * This page is about to be returned from the page allocator
+ */
+static inline int check_new_page(struct page *page)
+{
+	if (likely(page_expected_state(page,
+				PAGE_FLAGS_CHECK_AT_PREP|__PG_HWPOISON)))
+		return 0;
+
+	check_new_page_bad(page);
+	return 1;
 }
 
 static inline bool free_pages_prezeroed(bool poisoned)
-- 
2.8.1