[PATCH] mm: memcontrol: clarify the uncharge_list() loop
From: Johannes Weiner
Date: Thu Mar 10 2016 - 15:51:58 EST
uncharge_list() does an unusual list walk because the function can
take regular lists with dedicated list_heads as well as singleton
lists where a single page is passed via the page->lru list node.
This can sometimes lead to confusion as well as suggestions to replace
the loop with a list_for_each_entry(), which wouldn't work.
Signed-off-by: Johannes Weiner <hannes@xxxxxxxxxxx>
mm/memcontrol.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 8614e0d750e5..fa7bf354ae32 100644
@@ -5420,6 +5420,10 @@ static void uncharge_list(struct list_head *page_list)
struct list_head *next;
struct page *page;
+ * Note that the list can be a single page->lru; hence the
+ * do-while loop instead of a simple list_for_each_entry().
next = page_list->next;
unsigned int nr_pages = 1;