Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755689AbaDVKRy (ORCPT ); Tue, 22 Apr 2014 06:17:54 -0400 Received: from mail-ig0-f171.google.com ([209.85.213.171]:64998 "EHLO mail-ig0-f171.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752368AbaDVKRt (ORCPT ); Tue, 22 Apr 2014 06:17:49 -0400 MIME-Version: 1.0 In-Reply-To: <20140422094759.GC29311@dhcp22.suse.cz> References: <1397861935-31595-1-git-send-email-nasa4836@gmail.com> <20140422094759.GC29311@dhcp22.suse.cz> From: Jianyu Zhan Date: Tue, 22 Apr 2014 18:17:09 +0800 Message-ID: Subject: Re: [PATCH 1/2] mm/memcontrol.c: remove meaningless while loop in mem_cgroup_iter() To: Michal Hocko Cc: Johannes Weiner , Balbir Singh , kamezawa.hiroyu@jp.fujitsu.com, Cgroups , "linux-mm@kvack.org" , LKML Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Apr 22, 2014 at 5:47 PM, Michal Hocko wrote: > What about > 3. last_visited == last_node in the tree > > __mem_cgroup_iter_next returns NULL and the iterator would return > without visiting anything. Hi, Michal, yep, if 3 last_visited == last_node, then this means we have done a round-trip, thus __mem_cgroup_iter_next returns NULL, in turn mem_cgroup_iter() return NULL. This is what comments above mem_cgroup_iter() says: >Returns references to children of the hierarchy below @root, or >* @root itself, or %NULL after a full round-trip. Actually, this condition could be reduced to conditon 2.1 Thanks, Jianyu Zhan -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/