From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx205.postini.com [74.125.245.205]) by kanga.kvack.org (Postfix) with SMTP id 90AD86B006C for ; Mon, 2 Jul 2012 22:53:41 -0400 (EDT) Message-ID: <4FF25ED9.5070504@kernel.org> Date: Tue, 03 Jul 2012 11:54:17 +0900 From: Minchan Kim 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> <4FF2435F.2070302@redhat.com> In-Reply-To: <4FF2435F.2070302@redhat.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Rik van Riel Cc: Sasha Levin , Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Mel Gorman , jaschut@sandia.gov, kamezawa.hiroyu@jp.fujitsu.com, Dave Jones On 07/03/2012 09:57 AM, Rik van Riel wrote: > 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... > migrate_pfn does not necessarily start aligned to a pageblock. /* Setup to move all movable pages to the end of the zone */ cc->migrate_pfn = zone->zone_start_pfn; In isolate_freepages, high_pfn = low_pfn = cc->migrate_pfn + pageblock_nr_pages /* migrate_pfn doesn't aligned to a pageblock */ -- Kind regards, Minchan Kim -- 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