From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756382Ab2GCA5s (ORCPT ); Mon, 2 Jul 2012 20:57:48 -0400 Received: from mx1.redhat.com ([209.132.183.28]:43030 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756084Ab2GCA5q (ORCPT ); Mon, 2 Jul 2012 20:57:46 -0400 Message-ID: <4FF2435F.2070302@redhat.com> Date: Mon, 02 Jul 2012 20:57:03 -0400 From: Rik van Riel User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:12.0) Gecko/20120430 Thunderbird/12.0.1 MIME-Version: 1.0 To: Sasha Levin CC: Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Mel Gorman , jaschut@sandia.gov, minchan@kernel.org, kamezawa.hiroyu@jp.fujitsu.com, Dave Jones Subject: Re: [PATCH -mm v2] mm: have order > 0 compaction start off where it left References: <20120628135520.0c48b066@annuminas.surriel.com> <20120628135940.2c26ada9.akpm@linux-foundation.org> <4FECCB89.2050400@redhat.com> <20120628143546.d02d13f9.akpm@linux-foundation.org> <1341250950.16969.6.camel@lappy> In-Reply-To: <1341250950.16969.6.camel@lappy> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 07/02/2012 01:42 PM, Sasha Levin wrote: > On Thu, 2012-06-28 at 14:35 -0700, Andrew Morton wrote: >> On Thu, 28 Jun 2012 17:24:25 -0400 Rik van Riel wrote: >>> >>>>> @@ -463,6 +474,8 @@ static void isolate_freepages(struct zone *zone, >>>>> */ >>>>> if (isolated) >>>>> high_pfn = max(high_pfn, pfn); >>>>> + if (cc->order> 0) >>>>> + zone->compact_cached_free_pfn = high_pfn; >>>> >>>> Is high_pfn guaranteed to be aligned to pageblock_nr_pages here? I >>>> assume so, if lots of code in other places is correct but it's >>>> unobvious from reading this function. >>> >>> Reading the code a few more times, I believe that it is >>> indeed aligned to pageblock size. >> >> I'll slip this into -next for a while. >> >> --- a/mm/compaction.c~isolate_freepages-check-that-high_pfn-is-aligned-as-expected >> +++ a/mm/compaction.c >> @@ -456,6 +456,7 @@ static void isolate_freepages(struct zon >> } >> spin_unlock_irqrestore(&zone->lock, flags); >> >> + WARN_ON_ONCE(high_pfn& (pageblock_nr_pages - 1)); >> /* >> * Record the highest PFN we isolated pages from. When next >> * looking for free pages, the search will restart here as > > I've triggered the following with today's -next: I've been staring at the migrate code for most of the afternoon, and am not sure how this is triggered. At this point, I'm going to focus my attention on addressing Minchan's comments on my code, and hoping someone who is more familiar with the migrate code knows how high_pfn ends up being not pageblock_nr_pages aligned... -- All rights reversed