From b4f615e971b155f5841b2697ff28ea7f204828b7 Mon Sep 17 00:00:00 2001
From: Marek Szyprowski <m.szyprowski@samsung.com>
Date: Thu, 29 Nov 2012 14:17:32 +1100
Subject: [PATCH] mm: cma: WARN if freed memory is still in use

Memory returned to free_contig_range() must have no other references.  Let
kernel to complain loudly if page reference count is not equal to 1.

Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Reviewed-by: Kyungmin Park <kyungmin.park@samsung.com>
Acked-by: Michal Nazarewicz <mina86@mina86.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
 mm/page_alloc.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index dc2abffca944..5fc7a5d6d28e 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -5944,8 +5944,13 @@ done:
 
 void free_contig_range(unsigned long pfn, unsigned nr_pages)
 {
-	for (; nr_pages--; ++pfn)
-		__free_page(pfn_to_page(pfn));
+	struct page *page = pfn_to_page(pfn);
+	int count = 0;
+	for (; nr_pages--; page++) {
+		count += page_count(page) != 1;
+		__free_page(page);
+	}
+	WARN(count != 0, "%d pages are still in use!\n", count);
 }
 #endif
 
-- 
2.39.5