From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx191.postini.com [74.125.245.191]) by kanga.kvack.org (Postfix) with SMTP id 974EE6B0068 for ; Mon, 2 Jul 2012 20:57:36 -0400 (EDT) Message-ID: <4FF2435F.2070302@redhat.com> Date: Mon, 02 Jul 2012 20:57:03 -0400 From: Rik van Riel MIME-Version: 1.0 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: owner-linux-mm@kvack.org List-ID: 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 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 -- 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