From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756435AbYIKVmY (ORCPT ); Thu, 11 Sep 2008 17:42:24 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753954AbYIKVmQ (ORCPT ); Thu, 11 Sep 2008 17:42:16 -0400 Received: from smtp1.linux-foundation.org ([140.211.169.13]:57888 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753903AbYIKVmQ (ORCPT ); Thu, 11 Sep 2008 17:42:16 -0400 Date: Thu, 11 Sep 2008 14:41:55 -0700 From: Andrew Morton To: Mel Gorman Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, kamezawa.hiroyu@jp.fujitsu.com, apw@shadowen.org Subject: Re: [PATCH] Mark the correct zone as full when scanning zonelists Message-Id: <20080911144155.c70ef145.akpm@linux-foundation.org> In-Reply-To: <20080911212550.GA18087@csn.ul.ie> References: <20080911212550.GA18087@csn.ul.ie> X-Mailer: Sylpheed version 2.2.4 (GTK+ 2.8.20; i486-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 11 Sep 2008 22:25:51 +0100 Mel Gorman wrote: > The for_each_zone_zonelist() uses a struct zoneref *z cursor when scanning > zonelists to keep track of where in the zonelist it is. The zoneref that > is returned corresponds to the the next zone that is to be scanned, not > the current one as it originally thought of as an opaque list. > > When the page allocator is scanning a zonelist, it marks zones that it > temporarily full zones to eliminate near-future scanning attempts. That sentence needs help. > It uses > the zoneref for the marking and consequently the incorrect zone gets marked > full. This leads to a suitable zone being skipped in the mistaken belief > it is full. This patch corrects the problem by changing zoneref to be the > current zone being scanned instead of the next one. Applicable to 2.6.26 as well, yes? Someone reported a bug a few weeks ago which I think this patch will fix, yes? I don't remember who that was, nor do I recall the precise details of what the userspace-visible (mis)behaviour was. Are you able to fill in the gaps here? Put yourself in the position of a poor little -stable maintainer scratching his head wondering ytf he was sent this patch. Thanks. From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Thu, 11 Sep 2008 14:41:55 -0700 From: Andrew Morton Subject: Re: [PATCH] Mark the correct zone as full when scanning zonelists Message-Id: <20080911144155.c70ef145.akpm@linux-foundation.org> In-Reply-To: <20080911212550.GA18087@csn.ul.ie> References: <20080911212550.GA18087@csn.ul.ie> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Mel Gorman Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, kamezawa.hiroyu@jp.fujitsu.com, apw@shadowen.org List-ID: On Thu, 11 Sep 2008 22:25:51 +0100 Mel Gorman wrote: > The for_each_zone_zonelist() uses a struct zoneref *z cursor when scanning > zonelists to keep track of where in the zonelist it is. The zoneref that > is returned corresponds to the the next zone that is to be scanned, not > the current one as it originally thought of as an opaque list. > > When the page allocator is scanning a zonelist, it marks zones that it > temporarily full zones to eliminate near-future scanning attempts. That sentence needs help. > It uses > the zoneref for the marking and consequently the incorrect zone gets marked > full. This leads to a suitable zone being skipped in the mistaken belief > it is full. This patch corrects the problem by changing zoneref to be the > current zone being scanned instead of the next one. Applicable to 2.6.26 as well, yes? Someone reported a bug a few weeks ago which I think this patch will fix, yes? I don't remember who that was, nor do I recall the precise details of what the userspace-visible (mis)behaviour was. Are you able to fill in the gaps here? Put yourself in the position of a poor little -stable maintainer scratching his head wondering ytf he was sent this patch. Thanks. -- 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