From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-f180.google.com (mail-pf0-f180.google.com [209.85.192.180]) by kanga.kvack.org (Postfix) with ESMTP id D309B6B0005 for ; Wed, 23 Mar 2016 20:06:58 -0400 (EDT) Received: by mail-pf0-f180.google.com with SMTP id u190so42703589pfb.3 for ; Wed, 23 Mar 2016 17:06:58 -0700 (PDT) Received: from lgeamrelo13.lge.com (LGEAMRELO13.lge.com. [156.147.23.53]) by mx.google.com with ESMTP id f86si7650454pfd.122.2016.03.23.17.06.54 for ; Wed, 23 Mar 2016 17:06:55 -0700 (PDT) Date: Thu, 24 Mar 2016 09:08:31 +0900 From: Joonsoo Kim Subject: Re: [PATCH 4/6] mm/vmstat: add zone range overlapping check Message-ID: <20160324000831.GA7194@js1304-P5Q-DELUXE> References: <1457940697-2278-1-git-send-email-iamjoonsoo.kim@lge.com> <1457940697-2278-5-git-send-email-iamjoonsoo.kim@lge.com> <56F2AC92.9070600@suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <56F2AC92.9070600@suse.cz> Sender: owner-linux-mm@kvack.org List-ID: To: Vlastimil Babka Cc: Andrew Morton , Rik van Riel , Johannes Weiner , Mel Gorman , Laura Abbott , Minchan Kim , Marek Szyprowski , Michal Nazarewicz , "Aneesh Kumar K.V" , linux-mm@kvack.org, linux-kernel@vger.kernel.org, "Rafael J. Wysocki" On Wed, Mar 23, 2016 at 03:47:46PM +0100, Vlastimil Babka wrote: > On 03/14/2016 08:31 AM, js1304@gmail.com wrote: > >From: Joonsoo Kim > > > >There is a system that node's pfn are overlapped like as following. > > > >-----pfn--------> > >N0 N1 N2 N0 N1 N2 > > > >Therefore, we need to care this overlapping when iterating pfn range. > > > >There are two places in vmstat.c that iterates pfn range and > >they don't consider this overlapping. Add it. > > > >Without this patch, above system could over count pageblock number > >on a zone. > > > >Signed-off-by: Joonsoo Kim > >--- > > mm/vmstat.c | 7 +++++++ > > 1 file changed, 7 insertions(+) > > > >diff --git a/mm/vmstat.c b/mm/vmstat.c > >index 5e43004..0a726e3 100644 > >--- a/mm/vmstat.c > >+++ b/mm/vmstat.c > >@@ -1010,6 +1010,9 @@ static void pagetypeinfo_showblockcount_print(struct seq_file *m, > > if (!memmap_valid_within(pfn, page, zone)) > > continue; > > The above already does this for each page within the block, but it's > guarded by CONFIG_ARCH_HAS_HOLES_MEMORYMODEL. I guess that's not the > case of your system, right? > > I guess your added check should go above this, though. Also what > about employing pageblock_pfn_to_page() here and in all other > applicable places, so it's unified and optimized by > zone->contiguous? Comment on memmap_valid_within() in mmzone.h says that page_zone() linkages could be broken in that system even if pfn_valid() returns true. So, we cannot do zone check before it. In fact, I wonder how that system works fine under the situation where there are many pfn interators which doesn't check memmap_valid_within(). I guess there may be enough constraint. Anyway, I think that it is another issue and would be revisited later. 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