Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756922Ab2FWEkP (ORCPT ); Sat, 23 Jun 2012 00:40:15 -0400 Received: from fgwmail6.fujitsu.co.jp ([192.51.44.36]:60459 "EHLO fgwmail6.fujitsu.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751739Ab2FWEkN (ORCPT ); Sat, 23 Jun 2012 00:40:13 -0400 X-SecurityPolicyCheck: OK by SHieldMailChecker v1.7.4 Message-ID: <4FE5482C.3010501@jp.fujitsu.com> Date: Sat, 23 Jun 2012 13:38:04 +0900 From: Kamezawa Hiroyuki User-Agent: Mozilla/5.0 (Windows NT 6.0; rv:13.0) Gecko/20120614 Thunderbird/13.0.1 MIME-Version: 1.0 To: Minchan Kim CC: undisclosed-recipients:"; KOSAKI Motohiro" , Aaditya Kumar , Mel Gorman , "linux-mm@kvack.org" , LKML Illegal-Object: Syntax error in CC: address found on vger.kernel.org: CC: undisclosed-recipients:;KOSAKI Motohiro ^-missing end of address Subject: Re: Accounting problem of MIGRATE_ISOLATED freed page References: <4FE169B1.7020600@kernel.org> <4FE16E80.9000306@gmail.com> <4FE18187.3050103@kernel.org> <4FE23069.5030702@gmail.com> <4FE26470.90401@kernel.org> <4FE27F15.8050102@kernel.org> <4FE2A937.6040701@kernel.org> <4FE2FCFB.4040808@jp.fujitsu.com> <4FE3C4E4.2050107@kernel.org> <4FE414A2.3000700@kernel.org> In-Reply-To: <4FE414A2.3000700@kernel.org> 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 Content-Length: 2313 Lines: 67 (2012/06/22 15:45), Minchan Kim wrote: > On 06/22/2012 10:05 AM, Minchan Kim wrote: > >> Second approach which is suggested by KOSAKI is what you mentioned. >> But the concern about second approach is how to make sure matched count increase/decrease of nr_isolated_areas. >> I mean how to make sure nr_isolated_areas would be zero when isolation is done. >> Of course, we can investigate all of current caller and make sure they don't make mistake >> now. But it's very error-prone if we consider future's user. >> So we might need test_set_pageblock_migratetype(page, MIGRATE_ISOLATE); > > > It's an implementation about above approach. > I like this approach. > diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h > index bf3404e..3e9a9e1 100644 > --- a/include/linux/mmzone.h > +++ b/include/linux/mmzone.h > @@ -474,6 +474,11 @@ struct zone { > * rarely used fields: > */ > const char *name; > + /* > + * the number of MIGRATE_ISOLATE pageblock > + * We need this for accurate free page counting. > + */ > + atomic_t nr_migrate_isolate; > } ____cacheline_internodealigned_in_smp; Isn't this counter modified only under zone->lock ? > > typedef enum { > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index 2c29b1c..6cb1f9f 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -219,6 +219,11 @@ EXPORT_SYMBOL(nr_online_nodes); > > int page_group_by_mobility_disabled __read_mostly; > > +/* > + * NOTE: > + * Don't use set_pageblock_migratetype(page, MIGRATE_ISOLATE) direclty. > + * Instead, use {un}set_pageblock_isolate. > + */ > void set_pageblock_migratetype(struct page *page, int migratetype) > { > if (unlikely(page_group_by_mobility_disabled)) > @@ -1622,6 +1627,28 @@ bool zone_watermark_ok(struct zone *z, int order, unsigned long mark, > zone_page_state(z, NR_FREE_PAGES)); > } I'm glad if this function can be static...Hm. With easy grep, I think it can be... Thanks, -Kame -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/