From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-la0-f46.google.com (mail-la0-f46.google.com [209.85.215.46]) by kanga.kvack.org (Postfix) with ESMTP id 3DF5F6B00E0 for ; Tue, 4 Nov 2014 03:46:14 -0500 (EST) Received: by mail-la0-f46.google.com with SMTP id hs14so461487lab.5 for ; Tue, 04 Nov 2014 00:46:13 -0800 (PST) Received: from mx2.suse.de (cantor2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id db1si23871123lad.79.2014.11.04.00.46.12 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Tue, 04 Nov 2014 00:46:12 -0800 (PST) Message-ID: <54589251.2020105@suse.cz> Date: Tue, 04 Nov 2014 09:46:09 +0100 From: Vlastimil Babka MIME-Version: 1.0 Subject: Re: [PATCH v2 for v3.18] mm/compaction: skip the range until proper target pageblock is met References: <1415068649-18040-1-git-send-email-iamjoonsoo.kim@lge.com> In-Reply-To: <1415068649-18040-1-git-send-email-iamjoonsoo.kim@lge.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Joonsoo Kim , Andrew Morton Cc: David Rientjes , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Minchan Kim , Michal Nazarewicz , Naoya Horiguchi , Christoph Lameter , Rik van Riel , Mel Gorman , Zhang Yanfei On 11/04/2014 03:37 AM, Joonsoo Kim wrote: > commit 7d49d8868336 ("mm, compaction: reduce zone checking frequency in > the migration scanner") makes side-effect that change iteration > range calculation. Before change, block_end_pfn is calculated using > start_pfn, but, now, blindly add pageblock_nr_pages to previous value. > > This cause the problem that isolation_start_pfn is larger than > block_end_pfn when we isolate the page with more than pageblock order. > In this case, isolation would be failed due to invalid range parameter. > > To prevent this, this patch recalculate the range to find valid target > pageblock. Without this patch, CMA with more than pageblock order always > fail, but, with this patch, it will succeed. > > Changes from v1: > recalculate the range rather than just skipping to find valid one. > add code comment. > > Signed-off-by: Joonsoo Kim Acked-by: Vlastimil Babka (nitpick below) > --- > mm/compaction.c | 10 ++++++++++ > 1 file changed, 10 insertions(+) > > diff --git a/mm/compaction.c b/mm/compaction.c > index ec74cf0..4f0151c 100644 > --- a/mm/compaction.c > +++ b/mm/compaction.c > @@ -479,6 +479,16 @@ isolate_freepages_range(struct compact_control *cc, > > block_end_pfn = min(block_end_pfn, end_pfn); > > + /* > + * pfn could pass the block_end_pfn if isolated freepage > + * is more than pageblock order. In this case, we adjust > + * scanning range to right one. > + */ > + if (pfn >= block_end_pfn) { > + block_end_pfn = ALIGN(pfn + 1, pageblock_nr_pages); > + block_end_pfn = min(block_end_pfn, end_pfn); > + } If you moved this up, there could be just one min(block_end_pfn, end_pfn) instance in the code. If the first min() makes block_end_pfn == end_pfn and pfn >= block_end_pfn, then pfn >= end_pfn and the loop would be terminated already (assuming this was why you left the first min() before the new check). But I don't mind if you leave it like this. > + > if (!pageblock_pfn_to_page(pfn, block_end_pfn, cc->zone)) > break; > > -- 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