From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <46718320.1010500@csn.ul.ie> Date: Thu, 14 Jun 2007 19:04:16 +0100 From: Mel Gorman MIME-Version: 1.0 Subject: Re: [RFC] memory unplug v5 [1/6] migration by kernel References: <20070614155630.04f8170c.kamezawa.hiroyu@jp.fujitsu.com> <20070614155929.2be37edb.kamezawa.hiroyu@jp.fujitsu.com> <20070614161146.5415f493.kamezawa.hiroyu@jp.fujitsu.com> <20070614164128.42882f74.kamezawa.hiroyu@jp.fujitsu.com> <20070614172936.12b94ad7.kamezawa.hiroyu@jp.fujitsu.com> <20070615010217.62908da3.kamezawa.hiroyu@jp.fujitsu.com> <20070615011536.beaa79c1.kamezawa.hiroyu@jp.fujitsu.com> In-Reply-To: <20070615011536.beaa79c1.kamezawa.hiroyu@jp.fujitsu.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: KAMEZAWA Hiroyuki Cc: Christoph Lameter , linux-mm@kvack.org, y-goto@jp.fujitsu.com, hugh@veritas.com List-ID: KAMEZAWA Hiroyuki wrote: > On Thu, 14 Jun 2007 09:12:37 -0700 (PDT) > Christoph Lameter wrote: > >>> An unmapped swapcache page, which is just added to LRU, may be accessed via migrate_page(). >>> But page->mapping is NULL yet. >> Yes then lets add a check for page->mapping == NULL there. >> >> if (!page->mapping) >> goto unlock; >> >> That will retry the migration on the next pass. Add some concise comment >> explaining the situation. This is general bug in page migration. >> > Ok, will do. thank you for your advice. > I am currently testing what I believe your patches currently look like. In combination with the isolate lru page fix patch, things are looking better than they were. Previously I had seen some very bizarre errors when migrating due to compaction of memory but I'm not seeing them now. I hadn't been reporting because it was difficult to tell if migration was at fault or what memory compaction was doing. -- 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