summaryrefslogtreecommitdiffstats
path: root/mm/internal.h
diff options
context:
space:
mode:
Diffstat (limited to 'mm/internal.h')
-rw-r--r--mm/internal.h8
1 files changed, 5 insertions, 3 deletions
diff --git a/mm/internal.h b/mm/internal.h
index 7e145e8..612c14f 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -143,9 +143,11 @@ isolate_migratepages_range(struct zone *zone, struct compact_control *cc,
#endif
/*
- * function for dealing with page's order in buddy system.
- * zone->lock is already acquired when we use these.
- * So, we don't need atomic page->flags operations here.
+ * This function returns the order of a free page in the buddy system. In
+ * general, page_zone(page)->lock must be held by the caller to prevent the
+ * page from being allocated in parallel and returning garbage as the order.
+ * If a caller does not hold page_zone(page)->lock, it must guarantee that the
+ * page cannot be allocated or merged in parallel.
*/
static inline unsigned long page_order(struct page *page)
{
OpenPOWER on IntegriCloud