From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755910Ab3CZUiF (ORCPT ); Tue, 26 Mar 2013 16:38:05 -0400 Received: from mx1.redhat.com ([209.132.183.28]:7570 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754922Ab3CZUiB (ORCPT ); Tue, 26 Mar 2013 16:38:01 -0400 Date: Tue, 26 Mar 2013 16:37:44 -0400 From: Naoya Horiguchi To: Michal Hocko Cc: linux-mm@kvack.org, Andrew Morton , Mel Gorman , Hugh Dickins , KOSAKI Motohiro , Andi Kleen , Hillf Danton , linux-kernel@vger.kernel.org Message-ID: <1364330264-4oj9uxvi-mutt-n-horiguchi@ah.jp.nec.com> In-Reply-To: <20130326100221.GN2295@dhcp22.suse.cz> References: <1363983835-20184-1-git-send-email-n-horiguchi@ah.jp.nec.com> <1363983835-20184-7-git-send-email-n-horiguchi@ah.jp.nec.com> <20130325133644.GY2154@dhcp22.suse.cz> <1364281578-4bs50rjv-mutt-n-horiguchi@ah.jp.nec.com> <20130326100221.GN2295@dhcp22.suse.cz> Subject: Re: [PATCH 06/10] migrate: add hugepage migration code to move_pages() Mime-Version: 1.0 Content-Type: text/plain; charset=iso-2022-jp Content-Transfer-Encoding: 7bit Content-Disposition: inline X-Mutt-References: <20130326100221.GN2295@dhcp22.suse.cz> X-Mutt-Fcc: ~/Maildir/sent/ User-Agent: Mutt 1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Mar 26, 2013 at 11:02:21AM +0100, Michal Hocko wrote: > On Tue 26-03-13 03:06:18, Naoya Horiguchi wrote: > > On Mon, Mar 25, 2013 at 02:36:44PM +0100, Michal Hocko wrote: > > > On Fri 22-03-13 16:23:51, Naoya Horiguchi wrote: > > > > @@ -1164,6 +1175,12 @@ static int do_move_page_to_node_array(struct mm_struct *mm, > > > [...] > > > > !migrate_all) > > > > goto put_and_set; > > > > > > > > + if (PageHuge(page)) { > > > > + get_page(page); > > > > + list_move_tail(&page->lru, &pagelist); > > > > + goto put_and_set; > > > > + } > > > > > > Why do you take an additional reference here? You have one from > > > follow_page already. > > > > For normal pages, follow_page(FOLL_GET) takes a refcount and > > isolate_lru_page() takes another one, so I think the same should > > be done for hugepages. Refcounting of this function looks tricky, > > and I'm not sure why existing code does like that. > > Ohh, I see. But the whole reference is taken just to release it in goto > put_and_set because isolate_lru_page elevates reference count because > other users require that. I think you do not have to mimic this behavior > here and you can drop get_page and use goto set_status. OK, thanks. Naoya From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx151.postini.com [74.125.245.151]) by kanga.kvack.org (Postfix) with SMTP id 99DC76B014D for ; Tue, 26 Mar 2013 16:37:58 -0400 (EDT) Date: Tue, 26 Mar 2013 16:37:44 -0400 From: Naoya Horiguchi Message-ID: <1364330264-4oj9uxvi-mutt-n-horiguchi@ah.jp.nec.com> In-Reply-To: <20130326100221.GN2295@dhcp22.suse.cz> References: <1363983835-20184-1-git-send-email-n-horiguchi@ah.jp.nec.com> <1363983835-20184-7-git-send-email-n-horiguchi@ah.jp.nec.com> <20130325133644.GY2154@dhcp22.suse.cz> <1364281578-4bs50rjv-mutt-n-horiguchi@ah.jp.nec.com> <20130326100221.GN2295@dhcp22.suse.cz> Subject: Re: [PATCH 06/10] migrate: add hugepage migration code to move_pages() Mime-Version: 1.0 Content-Type: text/plain; charset=iso-2022-jp Content-Transfer-Encoding: 7bit Content-Disposition: inline Sender: owner-linux-mm@kvack.org List-ID: To: Michal Hocko Cc: linux-mm@kvack.org, Andrew Morton , Mel Gorman , Hugh Dickins , KOSAKI Motohiro , Andi Kleen , Hillf Danton , linux-kernel@vger.kernel.org On Tue, Mar 26, 2013 at 11:02:21AM +0100, Michal Hocko wrote: > On Tue 26-03-13 03:06:18, Naoya Horiguchi wrote: > > On Mon, Mar 25, 2013 at 02:36:44PM +0100, Michal Hocko wrote: > > > On Fri 22-03-13 16:23:51, Naoya Horiguchi wrote: > > > > @@ -1164,6 +1175,12 @@ static int do_move_page_to_node_array(struct mm_struct *mm, > > > [...] > > > > !migrate_all) > > > > goto put_and_set; > > > > > > > > + if (PageHuge(page)) { > > > > + get_page(page); > > > > + list_move_tail(&page->lru, &pagelist); > > > > + goto put_and_set; > > > > + } > > > > > > Why do you take an additional reference here? You have one from > > > follow_page already. > > > > For normal pages, follow_page(FOLL_GET) takes a refcount and > > isolate_lru_page() takes another one, so I think the same should > > be done for hugepages. Refcounting of this function looks tricky, > > and I'm not sure why existing code does like that. > > Ohh, I see. But the whole reference is taken just to release it in goto > put_and_set because isolate_lru_page elevates reference count because > other users require that. I think you do not have to mimic this behavior > here and you can drop get_page and use goto set_status. OK, thanks. Naoya -- 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