From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Tue, 05 Aug 2008 20:19:56 +0900 From: KOSAKI Motohiro Subject: Re: Race condition between putback_lru_page and mem_cgroup_move_list In-Reply-To: <48982F9E.2080100@linux.vnet.ibm.com> References: <20080805151956.A885.KOSAKI.MOTOHIRO@jp.fujitsu.com> <48982F9E.2080100@linux.vnet.ibm.com> Message-Id: <20080805200556.A891.KOSAKI.MOTOHIRO@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: balbir@linux.vnet.ibm.com Cc: kosaki.motohiro@jp.fujitsu.com, Lee Schermerhorn , MinChan Kim , KAMEZAWA Hiroyuki , linux-mm , Rik van Riel , LKML List-ID: > In general yes, but in practice no. We have different paths through which a page > can be reclaimed. Consider the following > > 1. What happens if a global reclaim is in progress at the same time as memory > cgroup reclaim and they are both looking at the same page? > 2. In the shared reclaim infrastructure, we move pages and update statistics for > pages belonging to a particular zone in a particular cgroup. hehe, you said mem_cgroup_per_zone::lru_lock is unnecessary lock. Also, we can two approach 1. the pages are allowed to exist in different zone of memcg zone and global zone. and recover later (by mem_cgroup_isolate_pages). here is current implementation. 2. the pages aren't allowed to exist in different zone of memcg zone and global zone. (you said its mail) if we select 2, I hope mem_cgroup_move_lists is called by ____pagevec_lru_add and add_page_to_unevictable_list. then, page's global lru transition become memcg lru transition automatically. it increase source code readability. -- 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