From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757700AbaHGNtW (ORCPT ); Thu, 7 Aug 2014 09:49:22 -0400 Received: from cantor2.suse.de ([195.135.220.15]:36160 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757376AbaHGNtV (ORCPT ); Thu, 7 Aug 2014 09:49:21 -0400 Message-ID: <53E383DD.6090500@suse.cz> Date: Thu, 07 Aug 2014 15:49:17 +0200 From: Vlastimil Babka User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.6.0 MIME-Version: 1.0 To: Joonsoo Kim , Andrew Morton CC: "Kirill A. Shutemov" , Rik van Riel , Mel Gorman , Johannes Weiner , Minchan Kim , Yasuaki Ishimatsu , Zhang Yanfei , "Srivatsa S. Bhat" , Tang Chen , Naoya Horiguchi , Bartlomiej Zolnierkiewicz , Wen Congyang , Marek Szyprowski , Michal Nazarewicz , Laura Abbott , Heesub Shin , "Aneesh Kumar K.V" , Ritesh Harjani , t.stanislaws@samsung.com, Gioh Kim , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2 2/8] mm/isolation: remove unstable check for isolated page References: <1407309517-3270-1-git-send-email-iamjoonsoo.kim@lge.com> <1407309517-3270-4-git-send-email-iamjoonsoo.kim@lge.com> In-Reply-To: <1407309517-3270-4-git-send-email-iamjoonsoo.kim@lge.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 08/06/2014 09:18 AM, Joonsoo Kim wrote: > The check '!PageBuddy(page) && page_count(page) == 0 && > migratetype == MIGRATE_ISOLATE' would mean the page on free processing. What is "the page on free processing"? I thought this test means the page is on some CPU's pcplist? > Although it could go into buddy allocator within a short time, > futher operation such as isolate_freepages_range() in CMA, called after > test_page_isolated_in_pageblock(), could be failed due to this unstability By "unstability" you mean the page can be allocated again from the pcplist instead of being freed to buddy list? > since it requires that the page is on buddy. I think that removing > this unstability is good thing. > > And, following patch makes isolated freepage has new status matched with > this condition and this check is the obstacle to that change. So remove > it. You could also say that pages from isolated pageblocks can no longer appear on pcplists after the later patches. > Signed-off-by: Joonsoo Kim > --- > mm/page_isolation.c | 6 +----- > 1 file changed, 1 insertion(+), 5 deletions(-) > > diff --git a/mm/page_isolation.c b/mm/page_isolation.c > index d1473b2..3100f98 100644 > --- a/mm/page_isolation.c > +++ b/mm/page_isolation.c > @@ -198,11 +198,7 @@ __test_page_isolated_in_pageblock(unsigned long pfn, unsigned long end_pfn, > MIGRATE_ISOLATE); > } > pfn += 1 << page_order(page); > - } > - else if (page_count(page) == 0 && > - get_freepage_migratetype(page) == MIGRATE_ISOLATE) > - pfn += 1; > - else if (skip_hwpoisoned_pages && PageHWPoison(page)) { > + } else if (skip_hwpoisoned_pages && PageHWPoison(page)) { > /* > * The HWPoisoned page may be not in buddy > * system, and page_count() is not 0. >