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. [[email protected]: support sparsemem] Signed-off-by: Marek Szyprowski <[email protected]> Reviewed-by: Kyungmin Park <[email protected]> Acked-by: Michal Nazarewicz <[email protected]> Signed-off-by: David Rientjes <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
dokyukim · Dec 21, 2012 · bcc2b02 · bcc2b02
1 parent b66c598
commit bcc2b02
Showing 1 changed file with 9 additions and 2 deletions.
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
@@ -5978,8 +5978,15 @@ int alloc_contig_range(unsigned long start, unsigned long end,
 
 void free_contig_range(unsigned long pfn, unsigned nr_pages)
 {
-	for (; nr_pages--; ++pfn)
-		__free_page(pfn_to_page(pfn));
+	unsigned int count = 0;
+
+	for (; nr_pages--; pfn++) {
+		struct page *page = pfn_to_page(pfn);
+
+		count += page_count(page) != 1;
+		__free_page(page);
+	}
+	WARN(count != 0, "%d pages are still in use!\n", count);
 }
 #endif