From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-f45.google.com (mail-wm0-f45.google.com [74.125.82.45]) by kanga.kvack.org (Postfix) with ESMTP id A5B4D828E1 for ; Thu, 10 Mar 2016 15:51:40 -0500 (EST) Received: by mail-wm0-f45.google.com with SMTP id p65so3409711wmp.0 for ; Thu, 10 Mar 2016 12:51:40 -0800 (PST) Received: from gum.cmpxchg.org (gum.cmpxchg.org. [85.214.110.215]) by mx.google.com with ESMTPS id km6si7002804wjc.1.2016.03.10.12.51.39 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 10 Mar 2016 12:51:39 -0800 (PST) From: Johannes Weiner Subject: [PATCH] mm: memcontrol: clarify the uncharge_list() loop Date: Thu, 10 Mar 2016 15:50:15 -0500 Message-Id: <1457643015-8828-3-git-send-email-hannes@cmpxchg.org> Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton Cc: Michal Hocko , Vladimir Davydov , linux-mm@kvack.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, kernel-team@fb.com 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 --- mm/memcontrol.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 8614e0d750e5..fa7bf354ae32 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -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; do { unsigned int nr_pages = 1; -- 2.7.2 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org